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📄 iwinq.c

📁 这是一个mp3的源代码
💻 C
📖 第 1 页 / 共 2 页
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      coef += 7;
      sum >>= WINBITS;
      if (sum > 32767)
	 sum = 32767;
      else if (sum < -32768)
	 sum = -32768;
      *pcm = (short) sum;
      pcm += 2;
   }
/*--  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 = (short) sum;
   pcm += 2;

/*-- 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 = (short) sum;
      pcm += 2;
   }
}
/*--------------- 16 pt dual window (interleaved output) -----------------*/
void i_window16_dual_right(WININT * vbuf, int vb_ptr, short *pcm)
{
/* right identical to dual, for asm */
   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 = (short) sum;
      pcm += 2;
   }
/*--  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 = (short) sum;
   pcm += 2;

/*-- 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 = (short) sum;
      pcm += 2;
   }
}
/*------------------------------------------------------------*/
/*------------------- 8 pt window ------------------------------*/
void i_window8(WININT * vbuf, int vb_ptr, short *pcm)
{
   int i, j;
   unsigned int si, bx;
   WINCOEF *coef;
   INT32 sum;

/*-- first 4 --*/
   si = (vb_ptr + (4 + 3 * 16)) & 127;
   bx = (si + (8 + 128 - 3 * 16 + 2 * 16)) & 127;
   coef = iwincoef;
   for (i = 0; i < 4; i++)
   {
      sum = -WINMULT(vbuf[bx], (*coef++));
      for (j = 0; j < 3; j++)
      {
	 bx = (bx + 16) & 127;
	 sum += WINMULT(vbuf[si], (*coef++));
	 si = (si + 16) & 127;
	 sum -= WINMULT(vbuf[bx], (*coef++));
      }
      si = (si + (5 * 16 + 1)) & 127;
      bx = (bx + (16 + 4 * 16 - 1)) & 127;
      coef += (3 * 7);
      sum >>= WINBITS;
      if (sum > 32767)
	 sum = 32767;
      else if (sum < -32768)
	 sum = -32768;
      *pcm++ = (short) sum;
   }
/*--  special case --*/
   bx = (bx + (128 - 16)) & 127;
   sum = WINMULT(vbuf[bx], (*coef++));
   for (j = 0; j < 3; j++)
   {
      bx = (bx + 16) & 127;
      sum += WINMULT(vbuf[bx], (*coef++));
   }
   sum >>= WINBITS;
   if (sum > 32767)
      sum = 32767;
   else if (sum < -32768)
      sum = -32768;
   *pcm++ = (short) sum;

/*-- last 3 --*/
   coef = iwincoef + (111 - 3 * 7);	/* back pass through coefs */
   si = (si + (128 - 3 * 16 + 2 * 16 - 1)) & 127;
   bx = (bx + (16 + 3 * 16 + 2 * 16 + 1)) & 127;
   for (i = 0; i < 3; i++)
   {
      sum = WINMULT(vbuf[si], (*coef--));
      for (j = 0; j < 3; j++)
      {
	 si = (si + 16) & 127;
	 sum += WINMULT(vbuf[bx], (*coef--));
	 bx = (bx + 16) & 127;
	 sum += WINMULT(vbuf[si], (*coef--));
      }
      si = (si + (16 - 1 + 4 * 16)) & 127;
      bx = (bx + (5 * 16 + 1)) & 127;
      coef -= (3 * 7);
      sum >>= WINBITS;
      if (sum > 32767)
	 sum = 32767;
      else if (sum < -32768)
	 sum = -32768;
      *pcm++ = (short) sum;
   }
}
/*--------------- 8 pt dual window (interleaved output) --------------*/
void i_window8_dual(WININT * vbuf, int vb_ptr, short *pcm)
{
   int i, j;
   unsigned int si, bx;
   WINCOEF *coef;
   INT32 sum;

/*-- first 4 --*/
   si = (vb_ptr + (4 + 3 * 16)) & 127;
   bx = (si + (8 + 128 - 3 * 16 + 2 * 16)) & 127;
   coef = iwincoef;
   for (i = 0; i < 4; i++)
   {
      sum = -WINMULT(vbuf[bx], (*coef++));
      for (j = 0; j < 3; j++)
      {
	 bx = (bx + 16) & 127;
	 sum += WINMULT(vbuf[si], (*coef++));
	 si = (si + 16) & 127;
	 sum -= WINMULT(vbuf[bx], (*coef++));
      }
      si = (si + (5 * 16 + 1)) & 127;
      bx = (bx + (16 + 4 * 16 - 1)) & 127;
      coef += (3 * 7);
      sum >>= WINBITS;
      if (sum > 32767)
	 sum = 32767;
      else if (sum < -32768)
	 sum = -32768;
      *pcm = (short) sum;
      pcm += 2;
   }
/*--  special case --*/
   bx = (bx + (128 - 16)) & 127;
   sum = WINMULT(vbuf[bx], (*coef++));
   for (j = 0; j < 3; j++)
   {
      bx = (bx + 16) & 127;
      sum += WINMULT(vbuf[bx], (*coef++));
   }
   sum >>= WINBITS;
   if (sum > 32767)
      sum = 32767;
   else if (sum < -32768)
      sum = -32768;
   *pcm = (short) sum;
   pcm += 2;

/*-- last 3 --*/
   coef = iwincoef + (111 - 3 * 7);	/* back pass through coefs */
   si = (si + (128 - 3 * 16 + 2 * 16 - 1)) & 127;
   bx = (bx + (16 + 3 * 16 + 2 * 16 + 1)) & 127;
   for (i = 0; i < 3; i++)
   {
      sum = WINMULT(vbuf[si], (*coef--));
      for (j = 0; j < 3; j++)
      {
	 si = (si + 16) & 127;
	 sum += WINMULT(vbuf[bx], (*coef--));
	 bx = (bx + 16) & 127;
	 sum += WINMULT(vbuf[si], (*coef--));
      }
      si = (si + (16 - 1 + 4 * 16)) & 127;
      bx = (bx + (5 * 16 + 1)) & 127;
      coef -= (3 * 7);
      sum >>= WINBITS;
      if (sum > 32767)
	 sum = 32767;
      else if (sum < -32768)
	 sum = -32768;
      *pcm = (short) sum;
      pcm += 2;
   }
}
/*------------------------------------------------------------*/
/*--------------- 8 pt dual window (interleaved output) --------------*/
void i_window8_dual_right(WININT * vbuf, int vb_ptr, short *pcm)
{
   int i, j;
   unsigned int si, bx;
   WINCOEF *coef;
   INT32 sum;

/* right identical to dual, for asm */

/*-- first 4 --*/
   si = (vb_ptr + (4 + 3 * 16)) & 127;
   bx = (si + (8 + 128 - 3 * 16 + 2 * 16)) & 127;
   coef = iwincoef;
   for (i = 0; i < 4; i++)
   {
      sum = -WINMULT(vbuf[bx], (*coef++));
      for (j = 0; j < 3; j++)
      {
	 bx = (bx + 16) & 127;
	 sum += WINMULT(vbuf[si], (*coef++));
	 si = (si + 16) & 127;
	 sum -= WINMULT(vbuf[bx], (*coef++));
      }
      si = (si + (5 * 16 + 1)) & 127;
      bx = (bx + (16 + 4 * 16 - 1)) & 127;
      coef += (3 * 7);
      sum >>= WINBITS;
      if (sum > 32767)
	 sum = 32767;
      else if (sum < -32768)
	 sum = -32768;
      *pcm = (short) sum;
      pcm += 2;
   }
/*--  special case --*/
   bx = (bx + (128 - 16)) & 127;
   sum = WINMULT(vbuf[bx], (*coef++));
   for (j = 0; j < 3; j++)
   {
      bx = (bx + 16) & 127;
      sum += WINMULT(vbuf[bx], (*coef++));
   }
   sum >>= WINBITS;
   if (sum > 32767)
      sum = 32767;
   else if (sum < -32768)
      sum = -32768;
   *pcm = (short) sum;
   pcm += 2;

/*-- last 3 --*/
   coef = iwincoef + (111 - 3 * 7);	/* back pass through coefs */
   si = (si + (128 - 3 * 16 + 2 * 16 - 1)) & 127;
   bx = (bx + (16 + 3 * 16 + 2 * 16 + 1)) & 127;
   for (i = 0; i < 3; i++)
   {
      sum = WINMULT(vbuf[si], (*coef--));
      for (j = 0; j < 3; j++)
      {
	 si = (si + 16) & 127;
	 sum += WINMULT(vbuf[bx], (*coef--));
	 bx = (bx + 16) & 127;
	 sum += WINMULT(vbuf[si], (*coef--));
      }
      si = (si + (16 - 1 + 4 * 16)) & 127;
      bx = (bx + (5 * 16 + 1)) & 127;
      coef -= (3 * 7);
      sum >>= WINBITS;
      if (sum > 32767)
	 sum = 32767;
      else if (sum < -32768)
	 sum = -32768;
      *pcm = (short) sum;
      pcm += 2;
   }
}
/*--------------------------------------------------------*/

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