287 lines
7.3 KiB
C
287 lines
7.3 KiB
C
//=======================================================================
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// Copyright XashXT Group 2007 ©
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// snd_adpcm.c - microsoft adpcm decoder
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//=======================================================================
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#include "client.h"
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#include "snd_loc.h"
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// Intel ADPCM step variation table
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static int indexTable[16] = {-1, -1, -1, -1, 2, 4, 6, 8, -1, -1, -1, -1, 2, 4, 6, 8,};
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static int stepsizeTable[89] =
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{
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7, 8, 9, 10, 11, 12, 13, 14, 16, 17,
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19, 21, 23, 25, 28, 31, 34, 37, 41, 45,
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50, 55, 60, 66, 73, 80, 88, 97, 107, 118,
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130, 143, 157, 173, 190, 209, 230, 253, 279, 307,
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337, 371, 408, 449, 494, 544, 598, 658, 724, 796,
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876, 963, 1060, 1166, 1282, 1411, 1552, 1707, 1878, 2066,
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2272, 2499, 2749, 3024, 3327, 3660, 4026, 4428, 4871, 5358,
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5894, 6484, 7132, 7845, 8630, 9493, 10442, 11487, 12635, 13899,
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15289, 16818, 18500, 20350, 22385, 24623, 27086, 29794, 32767
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};
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void S_AdpcmEncode( short indata[], char outdata[], int len, struct adpcm_state *state )
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{
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short *inp; // Input buffer pointer
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signed char *outp; // output buffer pointer
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int val; // Current input sample value
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int sign; // Current adpcm sign bit
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int delta; // Current adpcm output value
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int diff; // Difference between val and sample
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int step; // Stepsize
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int valpred; // Predicted output value
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int vpdiff; // Current change to valpred
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int index; // Current step change index
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int outputbuffer; // place to keep previous 4-bit value
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int bufferstep; // toggle between outputbuffer/output
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outp = (signed char *)outdata;
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inp = indata;
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valpred = state->sample;
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index = state->index;
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step = stepsizeTable[index];
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outputbuffer = 0; // quiet a compiler warning
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bufferstep = 1;
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for(; len > 0; len-- )
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{
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val = *inp++;
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// Step 1 - compute difference with previous value
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diff = val - valpred;
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sign = (diff < 0) ? 8 : 0;
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if ( sign ) diff = (-diff);
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// Step 2 - Divide and clamp
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// Note:
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// This code *approximately* computes:
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// delta = diff*4/step;
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// vpdiff = (delta+0.5)*step/4;
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// but in shift step bits are dropped. The net result of this is
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// that even if you have fast mul/div hardware you cannot put it to
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// good use since the fixup would be too expensive.
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delta = 0;
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vpdiff = (step >> 3);
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if ( diff >= step )
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{
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delta = 4;
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diff -= step;
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vpdiff += step;
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}
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step >>= 1;
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if ( diff >= step )
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{
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delta |= 2;
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diff -= step;
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vpdiff += step;
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}
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step >>= 1;
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if ( diff >= step )
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{
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delta |= 1;
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vpdiff += step;
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}
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// Step 3 - Update previous value
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if ( sign ) valpred -= vpdiff;
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else valpred += vpdiff;
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// Step 4 - Clamp previous value to 16 bits
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if ( valpred > 32767 ) valpred = 32767;
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else if ( valpred < -32768 ) valpred = -32768;
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// Step 5 - Assemble value, update index and step values
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delta |= sign;
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index += indexTable[delta];
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if ( index < 0 ) index = 0;
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if ( index > 88 ) index = 88;
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step = stepsizeTable[index];
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// Step 6 - Output value
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if ( bufferstep ) outputbuffer = (delta << 4) & 0xf0;
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else *outp++ = (delta & 0x0f) | outputbuffer;
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bufferstep = !bufferstep;
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}
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// Output last step, if needed
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if( !bufferstep ) *outp++ = outputbuffer;
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state->sample = valpred;
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state->index = index;
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}
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void S_AdpcmDecode( const char indata[], short *outdata, int len, struct adpcm_state *state )
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{
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signed char *inp; // Input buffer pointer
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int outp; // output buffer pointer
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int sign; // Current adpcm sign bit
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int delta; // Current adpcm output value
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int step; // Stepsize
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int valpred; // Predicted value
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int vpdiff; // Current change to valpred
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int index; // Current step change index
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int inputbuffer; // place to keep next 4-bit value
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int bufferstep; // toggle between inputbuffer/input
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outp = 0;
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inp = (signed char *)indata;
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valpred = state->sample;
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index = state->index;
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step = stepsizeTable[index];
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bufferstep = 0;
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inputbuffer = 0; // quiet a compiler warning
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for (; len > 0; len-- )
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{
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// Step 1 - get the delta value
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if ( bufferstep ) delta = inputbuffer & 0xf;
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else
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{
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inputbuffer = *inp++;
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delta = (inputbuffer >> 4) & 0xf;
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}
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bufferstep = !bufferstep;
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// Step 2 - Find new index value (for later)
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index += indexTable[delta];
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if ( index < 0 ) index = 0;
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if ( index > 88 ) index = 88;
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// Step 3 - Separate sign and magnitude
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sign = delta & 8;
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delta = delta & 7;
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// Step 4 - Compute difference and new predicted value
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// Computes 'vpdiff = (delta+0.5)*step/4', but see comment
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// in adpcm_coder.
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vpdiff = step >> 3;
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if ( delta & 4 ) vpdiff += step;
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if ( delta & 2 ) vpdiff += step>>1;
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if ( delta & 1 ) vpdiff += step>>2;
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if ( sign ) valpred -= vpdiff;
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else valpred += vpdiff;
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// Step 5 - clamp output value
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if ( valpred > 32767 ) valpred = 32767;
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else if ( valpred < -32768 ) valpred = -32768;
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// Step 6 - Update step value
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step = stepsizeTable[index];
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// Step 7 - Output value
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outdata[outp] = valpred;
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outp++;
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}
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state->sample = valpred;
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state->index = index;
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}
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/*
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====================
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S_AdpcmMemoryNeeded
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Returns the amount of memory (in bytes) needed to store the samples in out internal adpcm format
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====================
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*/
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int S_AdpcmMemoryNeeded( const wavinfo_t *info )
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{
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float scale;
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int scaledSampleCount;
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int sampleMemory;
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int blockCount;
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int headerMemory;
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// determine scale to convert from input sampling rate to desired sampling rate
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scale = (float)info->rate / dma.speed;
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// calc number of samples at playback sampling rate
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scaledSampleCount = info->samples / scale;
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// calc memory need to store those samples using ADPCM at 4 bits per sample
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sampleMemory = scaledSampleCount / 2;
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// calc number of sample blocks needed of PAINTBUFFER_SIZE
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blockCount = scaledSampleCount / PAINTBUFFER_SIZE;
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if( scaledSampleCount % PAINTBUFFER_SIZE ) blockCount++;
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// calc memory needed to store the block headers
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headerMemory = blockCount * sizeof(adpcm_state_t);
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return sampleMemory + headerMemory;
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}
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/*
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====================
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S_AdpcmGetSamples
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====================
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*/
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void S_AdpcmGetSamples(sndBuffer *chunk, short *to)
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{
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adpcm_state_t state;
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byte *out;
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// get the starting state from the block header
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state.index = chunk->adpcm.index;
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state.sample = chunk->adpcm.sample;
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out = (byte *)chunk->sndChunk;
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S_AdpcmDecode( out, to, SND_CHUNK_SIZE_BYTE * 2, &state );
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}
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/*
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====================
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S_AdpcmEncodeSound
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====================
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*/
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void S_AdpcmEncodeSound( sfx_t *sfx, short *samples )
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{
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adpcm_state_t state;
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int inOffset = 0;
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int n, count;
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sndBuffer *newchunk, *chunk;
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byte *out;
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count = sfx->soundLength;
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state.index = 0;
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state.sample = samples[0];
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chunk = NULL;
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while( count )
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{
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n = count;
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if( n > SND_CHUNK_SIZE_BYTE * 2 ) n = SND_CHUNK_SIZE_BYTE * 2;
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newchunk = SND_malloc();
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if (sfx->soundData == NULL) sfx->soundData = newchunk;
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else chunk->next = newchunk;
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chunk = newchunk;
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// output the header
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chunk->adpcm.index = state.index;
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chunk->adpcm.sample = state.sample;
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out = (byte *)chunk->sndChunk;
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// encode the samples
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S_AdpcmEncode( samples + inOffset, out, n, &state );
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inOffset += n;
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count -= n;
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}
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}
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