1 @*********************************************************** 2 @ Function: WT_VoiceGain 3 @ Processor: ARM-E 4 @ Description: the main synthesis function when fetching 5 @ wavetable samples. 6 @ C-callable. 7 @ 8 @ Usage: 9 @ Usage: 10 @ WT_VoiceGain( 11 @ S_WT_VOICE *pWTVoice, 12 @ S_WT_FRAME *pWTFrame); 13 @ 14 @ Copyright 2004, 2005 Sonic Network, Inc. 15 @**************************************************************** 16 @ Revision Control: 17 @ $Revision: 814 $ 18 @ $Date: 2007-08-02 10:34:53 -0700 (Thu, 02 Aug 2007) $ 19 @**************************************************************** 20 @ 21 @ where: 22 @ S_WT_VOICE *psVoice 23 @ PASSED IN: r0 24 @ 25 @ S_WT_FRAME *pWTFrame 26 @ PASSED IN: r1 27 @**************************************************************** 28 29 30 31 .include "ARM_synth_constants_gnu.inc" 32 33 .arm 34 .text 35 36 .global WT_VoiceGain 37 38 @ Register usage 39 @ -------------- 40 pWTVoice .req r0 41 pWTFrame .req r1 42 pInputBuffer .req r2 43 pMixBuffer .req r3 44 45 tmp0 .req r4 46 tmp1 .req r5 47 tmp2 .req r1 @ reuse register 48 tmp3 .req r6 49 50 numSamples .req r9 51 52 .if STEREO_OUTPUT 53 gainIncLeft .req r7 54 gainIncRight .req r8 55 gainLeft .req r10 56 gainRight .req r11 57 .else 58 gainIncrement .req r7 59 gain .req r8 60 .endif 61 62 63 @ register context for local variables 64 @SaveRegs RLIST {r4-r11,lr} 65 @RestoreRegs RLIST {r4-r11,pc} 66 67 .func WT_VoiceGain 68 WT_VoiceGain: 69 70 STMFD sp!, {r4-r11,lr} 71 72 LDR pInputBuffer, [pWTFrame, #m_pAudioBuffer] 73 LDR pMixBuffer, [pWTFrame, #m_pMixBuffer] 74 LDR numSamples, [pWTFrame, #m_numSamples] 75 76 @---------------------------------------------------------------- 77 @ Stereo version 78 @---------------------------------------------------------------- 79 @ NOTE: instructions are reordered to reduce the effect of latency 80 @ due to storage and computational dependencies. 81 @---------------------------------------------------------------- 82 83 .if STEREO_OUTPUT 84 85 LDR tmp0, [pWTFrame, #m_prevGain] 86 LDR tmp1, [pWTFrame, #m_gainTarget] 87 88 LDRSH gainLeft, [pWTVoice, #m_gainLeft] 89 LDRSH gainRight, [pWTVoice, #m_gainRight] 90 91 MOV gainIncLeft, gainLeft 92 SMULBB gainLeft, tmp0, gainLeft 93 94 SMULBB gainIncLeft, tmp1, gainIncLeft 95 SUB gainIncLeft, gainIncLeft, gainLeft 96 MOV gainLeft, gainLeft, ASR #(NUM_MIXER_GUARD_BITS - 2) 97 MOV gainIncLeft, gainIncLeft, ASR #(SYNTH_UPDATE_PERIOD_IN_BITS + NUM_MIXER_GUARD_BITS - 2) 98 99 MOV gainIncRight, gainRight 100 SMULBB gainRight, tmp0, gainRight 101 102 SMULBB gainIncRight, tmp1, gainIncRight 103 SUB gainIncRight, gainIncRight, gainRight 104 MOV gainRight, gainRight, ASR #(NUM_MIXER_GUARD_BITS - 2) 105 MOV gainIncRight, gainIncRight, ASR #(SYNTH_UPDATE_PERIOD_IN_BITS + NUM_MIXER_GUARD_BITS - 2) 106 107 LDRSH tmp0, [pInputBuffer], #2 108 109 StereoGainLoop: 110 LDR tmp1, [pMixBuffer] 111 112 ADD gainLeft, gainLeft, gainIncLeft 113 114 SMLAWB tmp1, gainLeft, tmp0, tmp1 115 116 LDR tmp2, [pMixBuffer, #4] 117 118 ADD gainRight, gainRight, gainIncRight 119 120 STR tmp1, [pMixBuffer], #4 121 122 SMLAWB tmp2, gainRight, tmp0, tmp2 123 124 SUBS numSamples, numSamples, #1 125 126 LDRGTSH tmp0, [pInputBuffer], #2 127 128 STR tmp2, [pMixBuffer], #4 129 130 BGT StereoGainLoop 131 132 @---------------------------------------------------------------- 133 @ Mono version 134 @---------------------------------------------------------------- 135 .else 136 137 LDR gain, [pWTFrame, #m_prevGain] 138 MOV gain, gain, LSL #(NUM_MIXER_GUARD_BITS + 4) 139 LDR gainIncrement, [pWTFrame, #m_gainTarget] 140 MOV gainIncrement, gainIncrement, LSL #(NUM_MIXER_GUARD_BITS + 4) 141 SUB gainIncrement, gainIncrement, gain 142 MOV gainIncrement, gainIncrement, ASR #SYNTH_UPDATE_PERIOD_IN_BITS 143 144 MonoGainLoop: 145 146 LDRSH tmp0, [pInputBuffer], #NEXT_OUTPUT_PCM @ fetch voice output 147 148 LDR tmp1, [pMixBuffer] @ get left channel output sample 149 ADD gain, gain, gainIncrement @ gain step to eliminate zipper noise 150 SMULWB tmp0, gain, tmp0 @ sample * local gain 151 152 MOV tmp0, tmp0, ASR #1 @ add 6dB headroom 153 ADD tmp1, tmp0, tmp1 154 STR tmp1, [pMixBuffer], #4 @ save and bump pointer 155 156 SUBS numSamples, numSamples, #1 157 BGT MonoGainLoop 158 159 .endif @end Mono version 160 161 LDMFD sp!,{r4-r11,lr} 162 BX lr 163 164 .endfunc 165 .end 166 167
