mirror of
https://github.com/ScrelliCopter/VGM-Tools
synced 2025-02-21 04:09:25 +11:00
102 lines
2.4 KiB
C
102 lines
2.4 KiB
C
/* (c) 2017 Alex Barney (MIT) */
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#include <stdint.h>
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#include "common.h"
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#include "dsptool.h"
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static inline uint8_t GetHighNibble(uint8_t value)
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{
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return value >> 4 & 0xF;
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}
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static inline uint8_t GetLowNibble(uint8_t value)
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{
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return value & 0xF;
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}
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static inline int16_t Clamp16(int value)
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{
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if (value > INT16_MAX)
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return INT16_MAX;
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if (value < INT16_MIN)
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return INT16_MIN;
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return (int16_t)value;
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}
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void decode(uint8_t* src, int16_t* dst, ADPCMINFO* cxt, uint32_t samples)
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{
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short hist1 = cxt->yn1;
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short hist2 = cxt->yn2;
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short* coefs = cxt->coef;
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uint32_t frameCount = (samples + SAMPLES_PER_FRAME - 1) / SAMPLES_PER_FRAME;
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uint32_t samplesRemaining = samples;
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for (uint32_t i = 0; i < frameCount; i++)
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{
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int predictor = GetHighNibble(*src);
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int scale = 1 << GetLowNibble(*src++);
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short coef1 = coefs[predictor * 2];
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short coef2 = coefs[predictor * 2 + 1];
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uint32_t samplesToRead = MIN(SAMPLES_PER_FRAME, samplesRemaining);
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for (uint32_t s = 0; s < samplesToRead; s++)
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{
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int sample = (s & 0x1)
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? GetLowNibble(*src++)
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: GetHighNibble(*src);
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sample = sample >= 8 ? sample - 16 : sample;
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sample = (scale * sample) << 11;
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sample = (sample + 1024 + (coef1 * hist1 + coef2 * hist2)) >> 11;
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short finalSample = Clamp16(sample);
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hist2 = hist1;
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hist1 = finalSample;
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*dst++ = finalSample;
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}
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samplesRemaining -= samplesToRead;
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}
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}
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void getLoopContext(uint8_t* src, ADPCMINFO* cxt, uint32_t samples)
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{
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short hist1 = cxt->yn1;
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short hist2 = cxt->yn2;
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short* coefs = cxt->coef;
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uint8_t ps = 0;
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int frameCount = (int)((samples + SAMPLES_PER_FRAME - 1) / SAMPLES_PER_FRAME);
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uint32_t samplesRemaining = samples;
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for (int i = 0; i < frameCount; i++)
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{
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ps = *src;
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int predictor = GetHighNibble(*src);
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int scale = 1 << GetLowNibble(*src++);
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short coef1 = coefs[predictor * 2];
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short coef2 = coefs[predictor * 2 + 1];
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uint32_t samplesToRead = MIN(SAMPLES_PER_FRAME, samplesRemaining);
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for (uint32_t s = 0; s < samplesToRead; s++)
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{
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int sample = (s & 0x1)
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? GetLowNibble(*src++)
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: GetHighNibble(*src);
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sample = sample >= 8 ? sample - 16 : sample;
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sample = (scale * sample) << 11;
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sample = (sample + 1024 + (coef1 * hist1 + coef2 * hist2)) >> 11;
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short finalSample = Clamp16(sample);
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hist2 = hist1;
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hist1 = finalSample;
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}
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samplesRemaining -= samplesToRead;
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}
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cxt->loop_pred_scale = ps;
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cxt->loop_yn1 = hist1;
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cxt->loop_yn2 = hist2;
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}
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