📄 iwinbq.c
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/*____________________________________________________________________________
MP3 Decoding Libraries
Lanuguages used: C, C++, ASM
As much as I would love to, I cannot take
full credit for writing this code.
Xing Technology made MPEG-Layer 3 for us
to decode. =)
- ULTiMaTuM -
MPEG-Layer 3 (MP3)
Copyright (C) 1995-1997 Xing Technology
NOTE: I only edited the bare-minimum. 90%
of this is original decoding code...
Hmm... that sounds strange =)
____________________________________________________________________________*/
/*----- iwinbq.c ---------------------------------------------------
portable c
mpeg1/2 Layer I/II audio decode
conditional include to iwinm.c
quick integer window - 8 bit output
mods 1/8/97 warnings
--------------------------------------------------------------*/
/*--------------------------------------------------------------------*/
void i_windowB(WININT * vbuf, int vb_ptr, unsigned char *pcm)
{
int i, j;
unsigned int si, bx;
WINCOEF *coef;
INT32 sum;
/*-- first 16 --*/
si = (vb_ptr + (16 + 3 * 64)) & 511;
bx = (si + (32 + 512 - 3 * 64 + 2 * 64)) & 511;
coef = iwincoef;
for (i = 0; i < 16; i++)
{
sum = -WINMULT(vbuf[bx], (*coef++));
for (j = 0; j < 3; j++)
{
bx = (bx + 64) & 511;
sum += WINMULT(vbuf[si], (*coef++));
si = (si + 64) & 511;
sum -= WINMULT(vbuf[bx], (*coef++));
}
si = (si + (5 * 64 + 1)) & 511;
bx = (bx + (64 + 4 * 64 - 1)) & 511;
sum >>= WINBITS;
if (sum > 32767)
sum = 32767;
else if (sum < -32768)
sum = -32768;
*pcm++ = (unsigned char) ((sum >> 8) ^ 0x80);
}
/*-- special case --*/
bx = (bx + (512 - 64)) & 511;
sum = WINMULT(vbuf[bx], (*coef++));
for (j = 0; j < 3; j++)
{
bx = (bx + 64) & 511;
sum += WINMULT(vbuf[bx], (*coef++));
}
sum >>= WINBITS;
if (sum > 32767)
sum = 32767;
else if (sum < -32768)
sum = -32768;
*pcm++ = (unsigned char) ((sum >> 8) ^ 0x80);
/*-- last 15 --*/
coef = iwincoef + 111; /* back pass through coefs */
si = (si + (512 - 3 * 64 + 2 * 64 - 1)) & 511;
bx = (bx + (64 + 3 * 64 + 2 * 64 + 1)) & 511;
for (i = 0; i < 15; i++)
{
sum = WINMULT(vbuf[si], (*coef--));
for (j = 0; j < 3; j++)
{
si = (si + 64) & 511;
sum += WINMULT(vbuf[bx], (*coef--));
bx = (bx + 64) & 511;
sum += WINMULT(vbuf[si], (*coef--));
}
si = (si + (64 - 1 + 4 * 64)) & 511;
bx = (bx + (5 * 64 + 1)) & 511;
sum >>= WINBITS;
if (sum > 32767)
sum = 32767;
else if (sum < -32768)
sum = -32768;
*pcm++ = (unsigned char) ((sum >> 8) ^ 0x80);
}
}
/*------------------------------------------------------------*/
void i_windowB_dual(WININT * vbuf, int vb_ptr, unsigned char *pcm)
{
/* dual window interleaves output */
int i, j;
unsigned int si, bx;
WINCOEF *coef;
INT32 sum;
/*-- first 16 --*/
si = (vb_ptr + (16 + 3 * 64)) & 511;
bx = (si + (32 + 512 - 3 * 64 + 2 * 64)) & 511;
coef = iwincoef;
for (i = 0; i < 16; i++)
{
sum = -WINMULT(vbuf[bx], (*coef++));
for (j = 0; j < 3; j++)
{
bx = (bx + 64) & 511;
sum += WINMULT(vbuf[si], (*coef++));
si = (si + 64) & 511;
sum -= WINMULT(vbuf[bx], (*coef++));
}
si = (si + (5 * 64 + 1)) & 511;
bx = (bx + (64 + 4 * 64 - 1)) & 511;
sum >>= WINBITS;
if (sum > 32767)
sum = 32767;
else if (sum < -32768)
sum = -32768;
*pcm = (unsigned char) ((sum >> 8) ^ 0x80);
pcm += 2;
}
/*-- special case --*/
bx = (bx + (512 - 64)) & 511;
sum = WINMULT(vbuf[bx], (*coef++));
for (j = 0; j < 3; j++)
{
bx = (bx + 64) & 511;
sum += WINMULT(vbuf[bx], (*coef++));
}
sum >>= WINBITS;
if (sum > 32767)
sum = 32767;
else if (sum < -32768)
sum = -32768;
*pcm = (unsigned char) ((sum >> 8) ^ 0x80);
pcm += 2;
/*-- last 15 --*/
coef = iwincoef + 111; /* back pass through coefs */
si = (si + (512 - 3 * 64 + 2 * 64 - 1)) & 511;
bx = (bx + (64 + 3 * 64 + 2 * 64 + 1)) & 511;
for (i = 0; i < 15; i++)
{
sum = WINMULT(vbuf[si], (*coef--));
for (j = 0; j < 3; j++)
{
si = (si + 64) & 511;
sum += WINMULT(vbuf[bx], (*coef--));
bx = (bx + 64) & 511;
sum += WINMULT(vbuf[si], (*coef--));
}
si = (si + (64 - 1 + 4 * 64)) & 511;
bx = (bx + (5 * 64 + 1)) & 511;
sum >>= WINBITS;
if (sum > 32767)
sum = 32767;
else if (sum < -32768)
sum = -32768;
*pcm = (unsigned char) ((sum >> 8) ^ 0x80);
pcm += 2;
}
}
/*------------------------------------------------------------*/
void i_windowB_dual_right(WININT * vbuf, int vb_ptr, unsigned char *pcm)
{
/* right identical to dual, for asm */
/* dual window interleaves output */
int i, j;
unsigned int si, bx;
WINCOEF *coef;
INT32 sum;
/*-- first 16 --*/
si = (vb_ptr + (16 + 3 * 64)) & 511;
bx = (si + (32 + 512 - 3 * 64 + 2 * 64)) & 511;
coef = iwincoef;
for (i = 0; i < 16; i++)
{
sum = -WINMULT(vbuf[bx], (*coef++));
for (j = 0; j < 3; j++)
{
bx = (bx + 64) & 511;
sum += WINMULT(vbuf[si], (*coef++));
si = (si + 64) & 511;
sum -= WINMULT(vbuf[bx], (*coef++));
}
si = (si + (5 * 64 + 1)) & 511;
bx = (bx + (64 + 4 * 64 - 1)) & 511;
sum >>= WINBITS;
if (sum > 32767)
sum = 32767;
else if (sum < -32768)
sum = -32768;
*pcm = (unsigned char) ((sum >> 8) ^ 0x80);
pcm += 2;
}
/*-- special case --*/
bx = (bx + (512 - 64)) & 511;
sum = WINMULT(vbuf[bx], (*coef++));
for (j = 0; j < 3; j++)
{
bx = (bx + 64) & 511;
sum += WINMULT(vbuf[bx], (*coef++));
}
sum >>= WINBITS;
if (sum > 32767)
sum = 32767;
else if (sum < -32768)
sum = -32768;
*pcm = (unsigned char) ((sum >> 8) ^ 0x80);
pcm += 2;
/*-- last 15 --*/
coef = iwincoef + 111; /* back pass through coefs */
si = (si + (512 - 3 * 64 + 2 * 64 - 1)) & 511;
bx = (bx + (64 + 3 * 64 + 2 * 64 + 1)) & 511;
for (i = 0; i < 15; i++)
{
sum = WINMULT(vbuf[si], (*coef--));
for (j = 0; j < 3; j++)
{
si = (si + 64) & 511;
sum += WINMULT(vbuf[bx], (*coef--));
bx = (bx + 64) & 511;
sum += WINMULT(vbuf[si], (*coef--));
}
si = (si + (64 - 1 + 4 * 64)) & 511;
bx = (bx + (5 * 64 + 1)) & 511;
sum >>= WINBITS;
if (sum > 32767)
sum = 32767;
else if (sum < -32768)
sum = -32768;
*pcm = (unsigned char) ((sum >> 8) ^ 0x80);
pcm += 2;
}
}
/*------------------------------------------------------------*/
/*------------------------------------------------------------*/
/*------------------- 16 pt window ------------------------------*/
void i_windowB16(WININT * vbuf, int vb_ptr, unsigned char *pcm)
{
int i, j;
unsigned char si, bx;
WINCOEF *coef;
INT32 sum;
/*-- first 8 --*/
si = (unsigned char) (vb_ptr + 8 + 3 * 32);
bx = (unsigned char) (si + (16 + 256 - 3 * 32 + 2 * 32));
coef = iwincoef;
for (i = 0; i < 8; i++)
{
sum = -WINMULT(vbuf[bx], (*coef++));
for (j = 0; j < 3; j++)
{
bx += 32;
sum += WINMULT(vbuf[si], (*coef++));
si += 32;
sum -= WINMULT(vbuf[bx], (*coef++));
}
si += (5 * 32 + 1);
bx += (32 + 4 * 32 - 1);
coef += 7;
sum >>= WINBITS;
if (sum > 32767)
sum = 32767;
else if (sum < -32768)
sum = -32768;
*pcm++ = (unsigned char) ((sum >> 8) ^ 0x80);
}
/*-- special case --*/
bx += (256 - 32);
sum = WINMULT(vbuf[bx], (*coef++));
for (j = 0; j < 3; j++)
{
bx += 32;
sum += WINMULT(vbuf[bx], (*coef++));
}
sum >>= WINBITS;
if (sum > 32767)
sum = 32767;
else if (sum < -32768)
sum = -32768;
*pcm++ = (unsigned char) ((sum >> 8) ^ 0x80);
/*-- last 7 --*/
coef = iwincoef + (111 - 7); /* back pass through coefs */
si += (256 + -3 * 32 + 2 * 32 - 1);
bx += (32 + 3 * 32 + 2 * 32 + 1);
for (i = 0; i < 7; i++)
{
sum = WINMULT(vbuf[si], (*coef--));
for (j = 0; j < 3; j++)
{
si += 32;
sum += WINMULT(vbuf[bx], (*coef--));
bx += 32;
sum += WINMULT(vbuf[si], (*coef--));
}
si += (32 - 1 + 4 * 32);
bx += (5 * 32 + 1);
coef -= 7;
sum >>= WINBITS;
if (sum > 32767)
sum = 32767;
else if (sum < -32768)
sum = -32768;
*pcm++ = (unsigned char) ((sum >> 8) ^ 0x80);
}
}
/*--------------- 16 pt dual window (interleaved output) -----------------*/
void i_windowB16_dual(WININT * vbuf, int vb_ptr, unsigned char *pcm)
{
int i, j;
unsigned char si, bx;
WINCOEF *coef;
INT32 sum;
/*-- first 8 --*/
si = (unsigned char) (vb_ptr + 8 + 3 * 32);
bx = (unsigned char) (si + (16 + 256 - 3 * 32 + 2 * 32));
coef = iwincoef;
for (i = 0; i < 8; i++)
{
sum = -WINMULT(vbuf[bx], (*coef++));
for (j = 0; j < 3; j++)
{
bx += 32;
sum += WINMULT(vbuf[si], (*coef++));
si += 32;
sum -= WINMULT(vbuf[bx], (*coef++));
}
si += (5 * 32 + 1);
bx += (32 + 4 * 32 - 1);
coef += 7;
sum >>= WINBITS;
if (sum > 32767)
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