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@ -------------- 40pWTVoice .req r0 41pWTFrame .req r1 42pInputBuffer .req r2 43pMixBuffer .req r3 44 45tmp0 .req r4 46tmp1 .req r5 47tmp2 .req r1 @ reuse register 48tmp3 .req r6 49 50numSamples .req r9 51 52 .if STEREO_OUTPUT 53gainIncLeft .req r7 54gainIncRight .req r8 55gainLeft .req r10 56gainRight .req r11 57 .else 58gainIncrement .req r7 59gain .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 68WT_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 109StereoGainLoop: 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 144MonoGainLoop: 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