示例#1
0
GLOBAL void

jpeg_idct_4x4 (j_decompress_ptr cinfo, jpeg_component_info * compptr,

	       JCOEFPTR coef_block,

	       JSAMPARRAY output_buf, JDIMENSION output_col)

{

  INT32 tmp0, tmp2, tmp10, tmp12;

  INT32 z1, z2, z3, z4;

  JCOEFPTR inptr;

  ISLOW_MULT_TYPE * quantptr;

  int * wsptr;

  JSAMPROW outptr;

  JSAMPLE *range_limit = IDCT_range_limit(cinfo);

  int ctr;

  int workspace[DCTSIZE*4];	/* buffers data between passes */

  SHIFT_TEMPS



  /* Pass 1: process columns from input, store into work array. */



  inptr = coef_block;

  quantptr = (ISLOW_MULT_TYPE *) compptr->dct_table;

  wsptr = workspace;

  for (ctr = DCTSIZE; ctr > 0; inptr++, quantptr++, wsptr++, ctr--) {

    /* Don't bother to process column 4, because second pass won't use it */

    if (ctr == DCTSIZE-4)

      continue;

    if ((inptr[DCTSIZE*1] | inptr[DCTSIZE*2] | inptr[DCTSIZE*3] |

	 inptr[DCTSIZE*5] | inptr[DCTSIZE*6] | inptr[DCTSIZE*7]) == 0) {

      /* AC terms all zero; we need not examine term 4 for 4x4 output */

      int dcval = DEQUANTIZE(inptr[DCTSIZE*0], quantptr[DCTSIZE*0]) << PASS1_BITS;

      

      wsptr[DCTSIZE*0] = dcval;

      wsptr[DCTSIZE*1] = dcval;

      wsptr[DCTSIZE*2] = dcval;

      wsptr[DCTSIZE*3] = dcval;

      

      continue;

    }

    

    /* Even part */

    

    tmp0 = DEQUANTIZE(inptr[DCTSIZE*0], quantptr[DCTSIZE*0]);

    tmp0 <<= (CONST_BITS+1);

    

    z2 = DEQUANTIZE(inptr[DCTSIZE*2], quantptr[DCTSIZE*2]);

    z3 = DEQUANTIZE(inptr[DCTSIZE*6], quantptr[DCTSIZE*6]);



    tmp2 = MULTIPLY(z2, FIX_1_847759065) + MULTIPLY(z3, - FIX_0_765366865);

    

    tmp10 = tmp0 + tmp2;

    tmp12 = tmp0 - tmp2;

    

    /* Odd part */

    

    z1 = DEQUANTIZE(inptr[DCTSIZE*7], quantptr[DCTSIZE*7]);

    z2 = DEQUANTIZE(inptr[DCTSIZE*5], quantptr[DCTSIZE*5]);

    z3 = DEQUANTIZE(inptr[DCTSIZE*3], quantptr[DCTSIZE*3]);

    z4 = DEQUANTIZE(inptr[DCTSIZE*1], quantptr[DCTSIZE*1]);

    

    tmp0 = MULTIPLY(z1, - FIX_0_211164243) /* sqrt(2) * (c3-c1) */

	 + MULTIPLY(z2, FIX_1_451774981) /* sqrt(2) * (c3+c7) */

	 + MULTIPLY(z3, - FIX_2_172734803) /* sqrt(2) * (-c1-c5) */

	 + MULTIPLY(z4, FIX_1_061594337); /* sqrt(2) * (c5+c7) */

    

    tmp2 = MULTIPLY(z1, - FIX_0_509795579) /* sqrt(2) * (c7-c5) */

	 + MULTIPLY(z2, - FIX_0_601344887) /* sqrt(2) * (c5-c1) */

	 + MULTIPLY(z3, FIX_0_899976223) /* sqrt(2) * (c3-c7) */

	 + MULTIPLY(z4, FIX_2_562915447); /* sqrt(2) * (c1+c3) */



    /* Final output stage */

    

    wsptr[DCTSIZE*0] = (int) DESCALE(tmp10 + tmp2, CONST_BITS-PASS1_BITS+1);

    wsptr[DCTSIZE*3] = (int) DESCALE(tmp10 - tmp2, CONST_BITS-PASS1_BITS+1);

    wsptr[DCTSIZE*1] = (int) DESCALE(tmp12 + tmp0, CONST_BITS-PASS1_BITS+1);

    wsptr[DCTSIZE*2] = (int) DESCALE(tmp12 - tmp0, CONST_BITS-PASS1_BITS+1);

  }

  

  /* Pass 2: process 4 rows from work array, store into output array. */



  wsptr = workspace;

  for (ctr = 0; ctr < 4; ctr++) {

    outptr = output_buf[ctr] + output_col;

    /* It's not clear whether a zero row test is worthwhile here ... */



#ifndef NO_ZERO_ROW_TEST

    if ((wsptr[1] | wsptr[2] | wsptr[3] | wsptr[5] | wsptr[6] |

	 wsptr[7]) == 0) {

      /* AC terms all zero */

      JSAMPLE dcval = range_limit[(int) DESCALE((INT32) wsptr[0], PASS1_BITS+3)

				  & RANGE_MASK];

      

      outptr[0] = dcval;

      outptr[1] = dcval;

      outptr[2] = dcval;

      outptr[3] = dcval;

      

      wsptr += DCTSIZE;		/* advance pointer to next row */

      continue;

    }

#endif

    

    /* Even part */

    

    tmp0 = ((INT32) wsptr[0]) << (CONST_BITS+1);

    

    tmp2 = MULTIPLY((INT32) wsptr[2], FIX_1_847759065)

	 + MULTIPLY((INT32) wsptr[6], - FIX_0_765366865);

    

    tmp10 = tmp0 + tmp2;

    tmp12 = tmp0 - tmp2;

    

    /* Odd part */

    

    z1 = (INT32) wsptr[7];

    z2 = (INT32) wsptr[5];

    z3 = (INT32) wsptr[3];

    z4 = (INT32) wsptr[1];

    

    tmp0 = MULTIPLY(z1, - FIX_0_211164243) /* sqrt(2) * (c3-c1) */

	 + MULTIPLY(z2, FIX_1_451774981) /* sqrt(2) * (c3+c7) */

	 + MULTIPLY(z3, - FIX_2_172734803) /* sqrt(2) * (-c1-c5) */

	 + MULTIPLY(z4, FIX_1_061594337); /* sqrt(2) * (c5+c7) */

    

    tmp2 = MULTIPLY(z1, - FIX_0_509795579) /* sqrt(2) * (c7-c5) */

	 + MULTIPLY(z2, - FIX_0_601344887) /* sqrt(2) * (c5-c1) */

	 + MULTIPLY(z3, FIX_0_899976223) /* sqrt(2) * (c3-c7) */

	 + MULTIPLY(z4, FIX_2_562915447); /* sqrt(2) * (c1+c3) */



    /* Final output stage */

    

    outptr[0] = range_limit[(int) DESCALE(tmp10 + tmp2,

					  CONST_BITS+PASS1_BITS+3+1)

			    & RANGE_MASK];

    outptr[3] = range_limit[(int) DESCALE(tmp10 - tmp2,

					  CONST_BITS+PASS1_BITS+3+1)

			    & RANGE_MASK];

    outptr[1] = range_limit[(int) DESCALE(tmp12 + tmp0,

					  CONST_BITS+PASS1_BITS+3+1)

			    & RANGE_MASK];

    outptr[2] = range_limit[(int) DESCALE(tmp12 - tmp0,

					  CONST_BITS+PASS1_BITS+3+1)

			    & RANGE_MASK];

    

    wsptr += DCTSIZE;		/* advance pointer to next row */

  }

}
示例#2
0
文件: jidctred.c 项目: 0x4d52/ugen
jpeg_idct_2x2 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
	       JCOEFPTR coef_block,
	       JSAMPARRAY output_buf, JDIMENSION output_col)
{
  INT32 tmp0, tmp10, z1;
  JCOEFPTR inptr;
  ISLOW_MULT_TYPE * quantptr;
  int * wsptr;
  JSAMPROW outptr;
  JSAMPLE *range_limit = IDCT_range_limit(cinfo);
  int ctr;
  int workspace[DCTSIZE*2];	/* buffers data between passes */
  SHIFT_TEMPS

  /* Pass 1: process columns from input, store into work array. */

  inptr = coef_block;
  quantptr = (ISLOW_MULT_TYPE *) compptr->dct_table;
  wsptr = workspace;
  for (ctr = DCTSIZE; ctr > 0; inptr++, quantptr++, wsptr++, ctr--) {
    /* Don't bother to process columns 2,4,6 */
    if (ctr == DCTSIZE-2 || ctr == DCTSIZE-4 || ctr == DCTSIZE-6)
      continue;
    if (inptr[DCTSIZE*1] == 0 && inptr[DCTSIZE*3] == 0 &&
	inptr[DCTSIZE*5] == 0 && inptr[DCTSIZE*7] == 0) {
      /* AC terms all zero; we need not examine terms 2,4,6 for 2x2 output */
      int dcval = DEQUANTIZE(inptr[DCTSIZE*0], quantptr[DCTSIZE*0]) << PASS1_BITS;

      wsptr[DCTSIZE*0] = dcval;
      wsptr[DCTSIZE*1] = dcval;

      continue;
    }

    /* Even part */

    z1 = DEQUANTIZE(inptr[DCTSIZE*0], quantptr[DCTSIZE*0]);
    tmp10 = z1 << (CONST_BITS+2);

    /* Odd part */

    z1 = DEQUANTIZE(inptr[DCTSIZE*7], quantptr[DCTSIZE*7]);
    tmp0 = MULTIPLY(z1, - FIX_0_720959822); /* sqrt(2) * (c7-c5+c3-c1) */
    z1 = DEQUANTIZE(inptr[DCTSIZE*5], quantptr[DCTSIZE*5]);
    tmp0 += MULTIPLY(z1, FIX_0_850430095); /* sqrt(2) * (-c1+c3+c5+c7) */
    z1 = DEQUANTIZE(inptr[DCTSIZE*3], quantptr[DCTSIZE*3]);
    tmp0 += MULTIPLY(z1, - FIX_1_272758580); /* sqrt(2) * (-c1+c3-c5-c7) */
    z1 = DEQUANTIZE(inptr[DCTSIZE*1], quantptr[DCTSIZE*1]);
    tmp0 += MULTIPLY(z1, FIX_3_624509785); /* sqrt(2) * (c1+c3+c5+c7) */

    /* Final output stage */

    wsptr[DCTSIZE*0] = (int) DESCALE(tmp10 + tmp0, CONST_BITS-PASS1_BITS+2);
    wsptr[DCTSIZE*1] = (int) DESCALE(tmp10 - tmp0, CONST_BITS-PASS1_BITS+2);
  }

  /* Pass 2: process 2 rows from work array, store into output array. */

  wsptr = workspace;
  for (ctr = 0; ctr < 2; ctr++) {
    outptr = output_buf[ctr] + output_col;
    /* It's not clear whether a zero row test is worthwhile here ... */

#ifndef NO_ZERO_ROW_TEST
    if (wsptr[1] == 0 && wsptr[3] == 0 && wsptr[5] == 0 && wsptr[7] == 0) {
      /* AC terms all zero */
      JSAMPLE dcval = range_limit[(int) DESCALE((INT32) wsptr[0], PASS1_BITS+3)
				  & RANGE_MASK];

      outptr[0] = dcval;
      outptr[1] = dcval;

      wsptr += DCTSIZE;		/* advance pointer to next row */
      continue;
    }
#endif

    /* Even part */

    tmp10 = ((INT32) wsptr[0]) << (CONST_BITS+2);

    /* Odd part */

    tmp0 = MULTIPLY((INT32) wsptr[7], - FIX_0_720959822) /* sqrt(2) * (c7-c5+c3-c1) */
	 + MULTIPLY((INT32) wsptr[5], FIX_0_850430095) /* sqrt(2) * (-c1+c3+c5+c7) */
	 + MULTIPLY((INT32) wsptr[3], - FIX_1_272758580) /* sqrt(2) * (-c1+c3-c5-c7) */
	 + MULTIPLY((INT32) wsptr[1], FIX_3_624509785); /* sqrt(2) * (c1+c3+c5+c7) */

    /* Final output stage */

    outptr[0] = range_limit[(int) DESCALE(tmp10 + tmp0,
					  CONST_BITS+PASS1_BITS+3+2)
			    & RANGE_MASK];
    outptr[1] = range_limit[(int) DESCALE(tmp10 - tmp0,
					  CONST_BITS+PASS1_BITS+3+2)
			    & RANGE_MASK];

    wsptr += DCTSIZE;		/* advance pointer to next row */
  }
}