zsort_audio2.c

void ZSortBOSS_Audio2( u32 _w0, u32 _w1 )
{
	int len = _w1 >> 24;
	u16 *mem16 = (u16*)DMEM;

	// Destination address (in 16bit sample unit)
	u32 dst = (((u32*)DMEM)[0x10>>2] >> 1) ^ 1;

	/* Fixed point 8.16 */
	u32 fp0 = _w0 & 0xfffff;
	u32 fp1 = _w1 & 0xfffff;

	// Written by previous ZSortBOSS_MoveWord
	u32 volume_addr = 0x904>>1;
	u16 volume[2] = {
	  mem16[volume_addr + 1],
	  mem16[volume_addr],
	};

	for(int i = 0; i < len; i += 4) {
	  for(int j = 0; j < 4; j++) {

	    u64 val = i * fp0 + j * fp0 + fp1;

	    u32 fract = val & 0xffff;
	    u32 index = val >> 16;

	    s16 sample0 = mem16[((0x18 + index))^1];
	    s16 sample1 = mem16[((0x19 + index))^1];

	    s16 diff = sample0 - sample1;
	    s16 target_sample = mem16[dst];

	    for(int k = 0; k < 2; k++, dst += 2) {

	      s32 interpolated_diff = (diff * fract) >> 16;
	      s16 interpolated_sample = sample0 + interpolated_diff;

	      s32 mixed_sample = (volume[k] * interpolated_sample) >> 16;
	      s16 out_sample = target_sample + mixed_sample;

	      mem16[dst] = out_sample;
	    }
	  }
	}

	LOG(LOG_VERBOSE, "ZSortBOSS_Audio2 (0x%08x, 0x%08x)\n", _w0, _w1);
}