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8 | |
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9 | #import "AudioGenerator.h" |
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10 | |
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11 | |
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12 | |
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13 | #define SAMPLE_RATE_F 44100.f |
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14 | #define SIGNAL_WAVE_FREQUENCY 100.f |
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15 | |
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16 | |
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17 | |
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18 | |
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19 | |
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20 | #define longHIGH 0.000829649 |
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21 | #define longLOW 0.000797027 |
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22 | #define shortHIGH 0.000412649 |
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23 | #define shortLOW 0.000378351 |
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24 | |
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25 | #define IDLE_TIME_MS 20 |
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26 | |
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27 | |
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28 | volatile BOOL g_refreshCtrCode = NO; |
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29 | |
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30 | |
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31 | @interface AudioGenerator() |
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32 | { |
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33 | |
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34 | AudioUnit m_audioUnit; |
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35 | Float32 m_sampleRate; |
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36 | BOOL m_isPlaying; |
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37 | double m_signalPhaseCur; |
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38 | |
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39 | |
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40 | int waveBit_01_len[2]; |
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41 | Float32 *waveBit_01[2]; |
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42 | |
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43 | int ctrWaveMaxLen; |
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44 | int ctrWaveDataLen; |
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45 | Float32 *ctrWave; |
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46 | |
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47 | int ctrWaveHeadLen; |
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48 | Float32 *ctrWaveHead; |
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49 | |
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50 | int ctrWaveReadIdx; |
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51 | |
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52 | int idleWaveLen; |
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53 | int idleWaveReadIdx; |
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54 | } |
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55 | |
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56 | @end |
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57 | |
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58 | |
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59 | @implementation AudioGenerator { |
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60 | |
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61 | float sampleTime; |
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62 | int longHighLength, shortHighLength, longZeroLength, longLowLength, mediumLowLength, shortLowLength, waveBitLength; |
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63 | float *waveLongHigh, *waveShortHigh, *waveLongZero, *waveLongLow, *waveMediumLow, *waveShortLow, *waveBit; |
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64 | |
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65 | |
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66 | |
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67 | int MAX_BUFFER_SIZE; |
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68 | |
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69 | } |
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70 | |
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71 | @synthesize yaw, pitch, throttle; |
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72 | |
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73 | - (id) init |
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74 | { |
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75 | self = [super init]; |
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76 | if (self) { |
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77 | sampleTime = 1.0f / SAMPLE_RATE_F; |
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78 | |
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79 | [self prepareStaticArrays]; |
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80 | } |
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81 | return self; |
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82 | } |
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83 | |
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84 | #pragma mark - ---- interface ---- |
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85 | |
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86 | - (void) playWithThrottle: (int)t yaw: (int)y pitch: (int)p |
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87 | { |
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88 | self.yaw = y; |
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89 | self.pitch = p; |
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90 | self.throttle = t; |
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91 | |
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92 | [self audioUnitStart]; |
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93 | |
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94 | } |
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95 | |
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96 | |
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97 | - (void) stop |
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98 | { |
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99 | [self audioUnitStop]; |
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100 | } |
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101 | |
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102 | |
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103 | #pragma mark - ---- Audio Unit func ---- |
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104 | |
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105 | - (void) audioUnitStart |
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106 | { |
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107 | |
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108 | if (m_audioUnit == nil) { |
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109 | [self prepareAudioUnit]; |
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110 | } |
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111 | |
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112 | if (!m_isPlaying) { |
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113 | |
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114 | [self updateCtrCode:NO]; |
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115 | |
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116 | OSStatus status = AudioUnitInitialize(m_audioUnit); |
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117 | |
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118 | if (status != noErr) { |
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119 | NSLog(@"AudioUnitInitialize - error"); |
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120 | } |
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121 | |
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122 | |
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123 | status = AudioOutputUnitStart(m_audioUnit); |
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124 | if (status != noErr) { |
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125 | NSLog(@"AudioOutputUnitStart - error"); |
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126 | } |
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127 | |
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128 | m_isPlaying = YES; |
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129 | } |
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130 | else { |
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131 | [self updateCtrCode:YES]; |
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132 | } |
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133 | |
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134 | |
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135 | } |
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136 | |
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137 | |
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138 | - (void) audioUnitStop |
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139 | { |
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140 | |
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141 | if (m_isPlaying) { |
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142 | OSStatus status = AudioOutputUnitStop(m_audioUnit); |
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143 | if (status != noErr) { |
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144 | NSLog(@"AudioOutputUnitStop - error"); |
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145 | } |
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146 | |
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147 | m_isPlaying = NO; |
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148 | } |
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149 | |
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150 | if (m_audioUnit) { |
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151 | OSStatus status = AudioUnitUninitialize(m_audioUnit); |
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152 | if (status != noErr) { |
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153 | NSLog(@"AudioUnitUninitialize - error"); |
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154 | } |
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155 | |
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156 | status = AudioComponentInstanceDispose(m_audioUnit); |
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157 | if (status != noErr) { |
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158 | NSLog(@"AudioComponentInstanceDispose - error"); |
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159 | } |
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160 | |
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161 | m_audioUnit = nil; |
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162 | } |
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163 | |
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164 | |
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165 | } |
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166 | |
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167 | |
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168 | |
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169 | - (void) prepareAudioUnit |
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170 | { |
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171 | m_sampleRate = SAMPLE_RATE_F; |
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172 | m_isPlaying = NO; |
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173 | m_signalPhaseCur = 0.0; |
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174 | |
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175 | OSStatus status = noErr; |
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176 | |
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177 | AudioComponentDescription au_cd; |
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178 | au_cd.componentType = kAudioUnitType_Output; |
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179 | au_cd.componentSubType = kAudioUnitSubType_RemoteIO; |
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180 | au_cd.componentManufacturer = kAudioUnitManufacturer_Apple; |
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181 | au_cd.componentFlags = 0; |
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182 | au_cd.componentFlagsMask = 0; |
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183 | |
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184 | AudioComponent component = AudioComponentFindNext(NULL, &au_cd); |
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185 | if (component == NULL) { |
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186 | NSLog(@"AudioComponentFindNext - error"); |
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187 | } |
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188 | |
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189 | |
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190 | status = AudioComponentInstanceNew(component, &m_audioUnit); |
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191 | if (status != noErr) { |
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192 | NSLog(@"AudioComponentInstanceNew - error"); |
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193 | } |
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194 | |
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195 | |
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196 | AURenderCallbackStruct callbackStruct; |
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197 | callbackStruct.inputProc = renderAudioUnitCallback; |
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198 | callbackStruct.inputProcRefCon = (__bridge void *)(self); |
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199 | |
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200 | status = AudioUnitSetProperty(m_audioUnit, |
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201 | kAudioUnitProperty_SetRenderCallback, |
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202 | kAudioUnitScope_Input, |
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203 | 0, |
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204 | &callbackStruct, |
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205 | sizeof(AURenderCallbackStruct)); |
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206 | |
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207 | if (status != noErr) { |
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208 | NSLog(@"kAudioUnitProperty_SetRenderCallback - error"); |
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209 | } |
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210 | |
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211 | |
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212 | AudioStreamBasicDescription streamFormat; |
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213 | streamFormat.mSampleRate = m_sampleRate; |
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214 | streamFormat.mFormatID = kAudioFormatLinearPCM; |
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215 | streamFormat.mFormatFlags = kAudioFormatFlagsNativeFloatPacked | kAudioFormatFlagIsNonInterleaved; |
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216 | streamFormat.mChannelsPerFrame = 2; |
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217 | streamFormat.mBytesPerPacket = sizeof(Float32); |
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218 | streamFormat.mBytesPerFrame = sizeof(Float32); |
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219 | streamFormat.mFramesPerPacket = 1; |
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220 | streamFormat.mBitsPerChannel = 8 * sizeof(Float32); |
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221 | |
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222 | status = AudioUnitSetProperty(m_audioUnit, |
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223 | kAudioUnitProperty_StreamFormat, |
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224 | kAudioUnitScope_Input, |
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225 | 0, |
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226 | &streamFormat, |
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227 | sizeof(AudioStreamBasicDescription)); |
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228 | |
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229 | if (status != noErr) { |
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230 | NSLog(@"kAudioUnitProperty_StreamFormat - error"); |
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231 | } |
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232 | |
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233 | } |
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234 | |
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235 | |
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236 | OSStatus renderAudioUnitCallback(void* inRefCon, |
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237 | AudioUnitRenderActionFlags* ioActionFlags, |
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238 | const AudioTimeStamp* inTimeStamp, |
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239 | UInt32 inBusNumber, |
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240 | UInt32 inNumberFrames, |
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241 | AudioBufferList* ioData) |
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242 | { |
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243 | AudioGenerator *generator = (__bridge AudioGenerator*)inRefCon; |
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244 | |
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245 | Float32 *ctr_buffer = ioData->mBuffers[0].mData; |
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246 | [generator writeCtrWaveToBuffer:ctr_buffer maxSize:inNumberFrames]; |
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247 | |
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248 | Float32 *signal_buffer = ioData->mBuffers[1].mData; |
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249 | [generator writeSignalWaveToBuffer:signal_buffer maxSize:inNumberFrames]; |
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250 | |
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251 | return noErr; |
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252 | } |
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253 | |
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254 | |
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255 | - (void)writeCtrWaveToBuffer:(Float32*)buffer maxSize:(UInt32)frames |
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256 | { |
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257 | |
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258 | for (int i=0; i < frames; ++i) { |
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259 | |
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260 | if (g_refreshCtrCode) { |
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261 | ctrWaveReadIdx = 0; |
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262 | idleWaveReadIdx = 0; |
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263 | g_refreshCtrCode = NO; |
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264 | break; |
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265 | } |
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266 | |
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267 | if (ctrWaveReadIdx <= ctrWaveDataLen && idleWaveReadIdx == 0) { |
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268 | *buffer++ = ctrWave[ctrWaveReadIdx++]; |
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269 | } |
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270 | else if (ctrWaveReadIdx > ctrWaveDataLen && idleWaveReadIdx <= idleWaveLen) |
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271 | { |
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272 | *buffer++ = 0.0f; |
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273 | idleWaveReadIdx++; |
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274 | } |
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275 | else if (ctrWaveReadIdx > ctrWaveDataLen && idleWaveReadIdx > idleWaveLen) |
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276 | { |
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277 | ctrWaveReadIdx = 0; |
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278 | idleWaveReadIdx = 0; |
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279 | *buffer++ = ctrWave[ctrWaveReadIdx++]; |
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280 | } |
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281 | |
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282 | } |
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283 | } |
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284 | |
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285 | - (void)writeSignalWaveToBuffer:(Float32*)buffer maxSize:(UInt32)frames |
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286 | { |
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287 | double phase_step = SIGNAL_WAVE_FREQUENCY * 2.0 * M_PI / SAMPLE_RATE_F; |
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288 | |
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289 | for (int i = 0; i < frames; ++i){ |
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290 | float wave = sin(m_signalPhaseCur); |
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291 | *buffer++ = wave; |
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292 | m_signalPhaseCur += phase_step; |
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293 | |
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294 | if (m_signalPhaseCur > 2.0 * M_PI) { |
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295 | m_signalPhaseCur -= 2.0 * M_PI; |
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296 | } |
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297 | } |
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298 | } |
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299 | |
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300 | |
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301 | |
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302 | #pragma mark - ---- Audio Generator func ---- |
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303 | |
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304 | |
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305 | |
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306 | - (void) prepareStaticArrays |
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307 | { |
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308 | |
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309 | waveLongHigh = [self generateHalfSine:true halfPeriod:longHIGH]; |
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310 | longHighLength = [self arraySizeWithHalfPeriod:longHIGH]; |
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311 | waveLongLow = [self generateHalfSine:false halfPeriod:longLOW]; |
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312 | longLowLength = [self arraySizeWithHalfPeriod:longLOW]; |
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313 | waveShortHigh = [self generateHalfSine:true halfPeriod:shortHIGH]; |
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314 | shortHighLength = [self arraySizeWithHalfPeriod:shortHIGH]; |
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315 | waveShortLow = [self generateHalfSine:false halfPeriod:shortLOW]; |
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316 | shortLowLength = [self arraySizeWithHalfPeriod:shortLOW]; |
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317 | |
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318 | float mediumLow = 0.0005 - sampleTime; |
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319 | waveMediumLow = [self generateHalfSine:false halfPeriod:mediumLow]; |
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320 | mediumLowLength = [self arraySizeWithHalfPeriod:mediumLow]; |
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321 | |
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322 | |
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323 | longZeroLength = (int)floor((0.002 + 1 / SAMPLE_RATE_F) * SAMPLE_RATE_F); |
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324 | waveLongZero = malloc(longZeroLength); |
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325 | |
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326 | [self generateWaveBit]; |
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327 | |
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328 | [self generateCtrWaveHead]; |
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329 | [self generateWaveBit_01]; |
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330 | |
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331 | [self setupCtrWave]; |
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332 | } |
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333 | |
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334 | - (void)setupCtrWave |
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335 | { |
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336 | ctrWaveMaxLen = ctrWaveHeadLen + |
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337 | 27 * (waveBit_01_len[0] > waveBit_01_len[1] ? waveBit_01_len[0] : waveBit_01_len[1]) + |
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338 | longHighLength; |
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339 | |
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340 | idleWaveLen = (int)floor(IDLE_TIME_MS * 0.001f * SAMPLE_RATE_F); |
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341 | |
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342 | ctrWave = malloc(sizeof(Float32) * ctrWaveMaxLen); |
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343 | |
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344 | memcpy(ctrWave, ctrWaveHead, sizeof(Float32) * ctrWaveHeadLen); |
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345 | |
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346 | ctrWaveReadIdx = 0; |
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347 | idleWaveReadIdx = 0; |
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348 | } |
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349 | |
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350 | - (void)generateCtrWaveHead |
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351 | { |
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352 | int ctr_longH_len = [self arraySizeWithHalfPeriod:longHIGH - sampleTime * 2]; |
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353 | int ctr_shortL_len = [self arraySizeWithHalfPeriod:shortLOW + sampleTime * 2]; |
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354 | |
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355 | ctrWaveHeadLen = longLowLength + 2 * ctr_longH_len + 2 * ctr_shortL_len; |
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356 | ctrWaveHead = malloc(sizeof(Float32) * ctrWaveHeadLen); |
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357 | |
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358 | int idx = 0; |
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359 | |
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360 | for (int i=0; i < longLowLength; ++i) { |
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361 | ctrWaveHead[idx++] = waveLongLow[i]; |
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362 | } |
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363 | |
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364 | double increment = M_PI/((longHIGH - sampleTime * 2) * SAMPLE_RATE_F); |
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365 | double angle = 0; |
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366 | |
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367 | for (int i=0; i < ctr_longH_len; ++i) { |
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368 | Float32 value = sinf(angle); |
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369 | ctrWaveHead[idx + ctr_longH_len + ctr_shortL_len] = value; |
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370 | ctrWaveHead[idx++] = value; |
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371 | angle += increment; |
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372 | } |
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373 | |
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374 | memset(ctrWaveHead + idx, 0, sizeof(Float32) * ctr_shortL_len); |
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375 | memset(ctrWaveHead + (idx + ctr_longH_len + ctr_shortL_len), 0, sizeof(Float32) * ctr_shortL_len); |
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376 | |
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377 | } |
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378 | |
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379 | - (void) generateWaveBit_01 |
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380 | { |
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381 | waveBit_01_len[0] = shortHighLength + shortLowLength; |
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382 | waveBit_01_len[1] = longHighLength + longLowLength; |
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383 | |
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384 | waveBit_01[0] = malloc(sizeof(Float32) * waveBit_01_len[0]); |
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385 | waveBit_01[1] = malloc(sizeof(Float32) * waveBit_01_len[1]); |
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386 | |
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387 | int idx = 0; |
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388 | for (int i=0; i < shortHighLength; ++i) { |
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389 | waveBit_01[0][idx++] = waveShortHigh[i]; |
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390 | } |
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391 | for (int i=0; i < shortLowLength; ++i) { |
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392 | waveBit_01[0][idx++] = waveShortLow[i]; |
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393 | } |
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394 | |
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395 | idx = 0; |
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396 | for (int i=0; i < longHighLength; ++i) { |
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397 | waveBit_01[1][idx++] = waveLongHigh[i]; |
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398 | } |
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399 | for (int i=0; i < longLowLength; ++i) { |
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400 | waveBit_01[1][idx++] = waveLongLow[i]; |
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401 | } |
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402 | |
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403 | } |
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404 | |
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405 | - (void) generateWaveBit |
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406 | { |
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407 | waveBitLength = longHighLength + longLowLength + shortHighLength + shortLowLength; |
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408 | waveBit = malloc(sizeof(waveBit) * waveBitLength); |
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409 | int c = 0; |
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410 | for (int i = 0; i < longHighLength; i++) { |
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411 | waveBit[c++] = waveLongHigh[i]; |
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412 | } |
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413 | for (int i = 0; i < longLowLength; i++) { |
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414 | waveBit[c++] = waveLongLow[i]; |
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415 | } |
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416 | for (int i = 0; i < shortHighLength; i++) { |
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417 | waveBit[c++] = waveShortHigh[i]; |
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418 | } |
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419 | for (int i = 0; i < shortLowLength; i++) { |
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420 | waveBit[c++] = waveShortLow[i]; |
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421 | } |
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422 | } |
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423 | |
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424 | |
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425 | |
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426 | |
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427 | - (int) codeChecksum:(int)code |
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428 | { |
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429 | int checksum = 0; |
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430 | for (int i = 0; i < 7; i++) { |
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431 | checksum += (code >> 4*i) & 15; |
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432 | } |
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433 | return 16 - (checksum & 15); |
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434 | } |
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435 | |
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436 | |
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437 | |
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438 | |
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439 | |
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440 | |
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441 | |
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442 | - (int) generateCode |
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443 | { |
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444 | int channel = 1; |
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445 | int code = throttle << 21; |
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446 | code += 1 << 20; |
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447 | code += yaw << 12; |
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448 | code += pitch << 4; |
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449 | code += ((channel >> 1) & 1) << 19; |
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450 | code += (channel & 1) << 11; |
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451 | return code + [self codeChecksum:code]; |
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452 | } |
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453 | |
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454 | - (void)updateCtrCode:(BOOL)refresh |
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455 | { |
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456 | int ctr_code = [self generateCode]; |
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457 | |
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458 | |
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459 | |
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460 | [self codeToWave:ctr_code]; |
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461 | |
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462 | if (refresh) { |
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463 | g_refreshCtrCode = YES; |
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464 | } |
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465 | |
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466 | } |
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467 | |
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468 | - (void)codeToWave:(int)code |
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469 | { |
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470 | Float32 *pos = ctrWave + ctrWaveHeadLen; |
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471 | |
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472 | for (int i=27; i >= 0 ; --i) { |
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473 | int bit = (code >> i) & 1; |
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474 | memcpy(pos, waveBit_01[bit], sizeof(Float32) * waveBit_01_len[bit]); |
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475 | pos += waveBit_01_len[bit]; |
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476 | } |
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477 | |
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478 | memcpy(pos, waveLongHigh, sizeof(Float32) * longHighLength); |
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479 | pos += longHighLength; |
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480 | |
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481 | ctrWaveDataLen = pos - ctrWave; |
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482 | int lost_len = ctrWaveMaxLen - ctrWaveDataLen; |
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483 | |
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484 | memset(pos, 0, sizeof(Float32) * lost_len); |
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485 | } |
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486 | |
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487 | |
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488 | |
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489 | |
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490 | - (int) writeBytesToBuffer:(Float32 *) buffer maxSize:(UInt32) frames |
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491 | { |
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492 | MAX_BUFFER_SIZE = sizeof(buffer) * frames; |
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493 | int position = 0; |
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494 | [self writeWaveToBuffer:buffer at:&position]; |
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495 | [self writeInitialWaveToBuffer:buffer at:&position]; |
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496 | |
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497 | return position; |
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498 | } |
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499 | |
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500 | - (void) writeInitialWaveToBuffer:(Float32 *) buffer at: (int *) position |
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501 | { |
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502 | [self writeWave123To: buffer at: position]; |
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503 | [self writeWave123To: buffer at: position]; |
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504 | [self writeWave456To: buffer at: position]; |
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505 | [self writeWave456To: buffer at: position]; |
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506 | [self writeWave456To: buffer at: position]; |
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507 | } |
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508 | |
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509 | - (void) writeWave123To:(Float32 *) buffer at:(int *) position |
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510 | { |
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511 | [self writeOriginalTo:buffer at: position]; |
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512 | [self writeArray:waveMediumLow to:buffer length:mediumLowLength at:position]; |
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513 | for (int i = 0; i < 4; i++) { |
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514 | [self writeShortHShortLTo:buffer at:position]; |
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515 | } |
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516 | [self writeArray:waveShortHigh to:buffer length:shortHighLength at:position]; |
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517 | [self writeMediumLShortHTo:buffer at:position]; |
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518 | [self writePauseInSamplesTo:buffer at:position]; |
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519 | } |
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520 | |
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521 | - (void) writeWave456To:(Float32 *) buffer at:(int *) position |
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522 | { |
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523 | [self writeOriginalTo:buffer at:position]; |
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524 | [self writeArray:waveShortLow to:buffer length:shortLowLength at:position]; |
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525 | for (int i = 0; i < 4; i++) { |
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526 | [self writeShortHShortLTo:buffer at:position]; |
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527 | } |
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528 | [self writeArray:waveShortHigh to:buffer length:shortHighLength at:position]; |
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529 | [self writeMediumLShortHTo:buffer at:position]; |
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530 | [self writePauseInSamplesTo:buffer at:position]; |
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531 | } |
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532 | |
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533 | |
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534 | - (void) writeOriginalTo:(Float32 *) buffer at:(int *) position |
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535 | { |
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536 | [self writeLongHLongZeroTo: buffer at: position]; |
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537 | [self writeLongHLongZeroTo: buffer at: position]; |
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538 | [self writeArray:waveLongHigh to:buffer length:longHighLength at:position]; |
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539 | [self writeMediumLShortHTo:buffer at:position]; |
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540 | } |
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541 | |
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542 | - (void) writeLongHLongZeroTo:(Float32 *) buffer at:(int *) position |
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543 | { |
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544 | [self writeArray:waveLongHigh to:buffer length:longHighLength at:position]; |
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545 | [self writeArray:waveLongZero to:buffer length:longZeroLength at:position]; |
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546 | } |
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547 | |
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548 | - (void) writeMediumLShortHTo:(Float32 *) buffer at:(int *) position |
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549 | { |
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550 | [self writeArray:waveMediumLow to:buffer length:mediumLowLength at:position]; |
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551 | [self writeArray:waveShortHigh to:buffer length:shortHighLength at:position]; |
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552 | } |
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553 | |
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554 | - (void) writeShortHShortLTo:(Float32 *) buffer at:(int *) position |
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555 | { |
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556 | [self writeArray:waveShortHigh to:buffer length:shortHighLength at:position]; |
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557 | [self writeArray:waveShortLow to:buffer length:shortLowLength at:position]; |
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558 | } |
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559 | |
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560 | - (void) writePauseInSamplesTo:(Float32 *) buffer at:(int *) position |
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561 | { |
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562 | int length = (int)floor(0.010 * SAMPLE_RATE_F); |
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563 | float arr[length]; |
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564 | [self writeArray:arr to:buffer length:length at:position]; |
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565 | } |
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566 | |
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567 | - (void) writeArray:(float *) array to:(Float32 *) buffer length: (int)length at:(int *) position |
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568 | { |
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569 | for (int i = 0; i < length; i++) { |
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570 | if (*position < MAX_BUFFER_SIZE) buffer[(*position)++] = array[i]; |
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571 | } |
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572 | } |
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573 | |
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574 | - (void) writeWaveToBuffer:(Float32 *) buffer at: (int *) position |
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575 | { |
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576 | [self halfSineGen: false halfPeriod: longLOW toBuffer:buffer at:position]; |
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577 | [self halfSineGen: true halfPeriod: longHIGH - sampleTime * 2 toBuffer:buffer at:position]; |
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578 | [self halfSineGen: false halfPeriod: shortLOW + sampleTime * 2 toBuffer:buffer at:position]; |
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579 | [self halfSineGen: true halfPeriod: longHIGH - sampleTime * 2 toBuffer:buffer at:position]; |
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580 | [self halfSineGen: false halfPeriod: shortLOW + sampleTime * 2 toBuffer:buffer at:position]; |
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581 | |
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582 | int code = [self generateCode]; |
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583 | for (int i=0; i < 27; i++) { |
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584 | buffer[(*position)++] = waveBit[((code >> (27 - i)) & 1)]; |
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585 | } |
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586 | for (int i = 0; i < longHighLength; i++) { |
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587 | buffer[(*position)++] = waveLongHigh[i]; |
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588 | } |
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589 | |
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590 | } |
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591 | |
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592 | |
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593 | |
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594 | |
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595 | |
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596 | |
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597 | |
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598 | |
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599 | |
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600 | - (void) halfSineGen:(BOOL)upper halfPeriod: (double)halfPeriod toBuffer:(Float32 *) buffer at:(int *) position |
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601 | { |
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602 | |
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603 | |
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604 | |
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605 | |
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606 | int sampleCount = [self arraySizeWithHalfPeriod:halfPeriod]; |
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607 | double increment = M_PI/(halfPeriod * SAMPLE_RATE_F); |
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608 | double angle = upper ? 0 : M_PI; |
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609 | |
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610 | for (int i = 0; i < sampleCount; i++) { |
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611 | buffer[(*position)++] = sinf(angle); |
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612 | angle += increment; |
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613 | } |
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614 | } |
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615 | |
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616 | - (int) arraySizeWithHalfPeriod: (double)halfPeriod |
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617 | { |
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618 | return (int)floor(halfPeriod * SAMPLE_RATE_F); |
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619 | } |
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620 | |
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621 | |
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622 | |
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623 | |
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624 | |
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625 | |
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626 | |
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627 | |
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628 | - (float *) generateHalfSine:(BOOL)upper halfPeriod: (double)halfPeriod |
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629 | { |
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630 | int sampleCount = [self arraySizeWithHalfPeriod:halfPeriod]; |
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631 | Float32 *array = malloc(sizeof(Float32) * sampleCount); |
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632 | double increment = M_PI/(halfPeriod * SAMPLE_RATE_F); |
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633 | double angle = 0; |
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634 | |
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635 | for (int i = 0; i < sampleCount; i++) { |
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636 | if (upper) { |
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637 | array[i] = sinf(angle); |
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638 | angle += increment; |
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639 | } |
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640 | else { |
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641 | array[i] = 0.0f; |
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642 | } |
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643 | |
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644 | } |
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645 | return array; |
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646 | } |
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647 | |
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648 | @end |
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