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authorOliver Schinagl <oliver@schinagl.nl>2005-05-16 20:02:56 (GMT)
committerOliver Schinagl <oliver@schinagl.nl>2005-05-16 20:02:56 (GMT)
commitf3fb4fe22f28b73dd9642f5973af008003133f16 (patch)
tree3bc8243515d0ecda1d06acf684c74d79019cc6d7
parent4ced72dcdb3e5e98e1407d2f85c3fcaace6a2d36 (diff)
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Some small stuff changed
-rw-r--r--src/fdct.c187
-rw-r--r--src/idct.c2
2 files changed, 27 insertions, 162 deletions
diff --git a/src/fdct.c b/src/fdct.c
index 10a222b..2dab7c5 100644
--- a/src/fdct.c
+++ b/src/fdct.c
@@ -1,114 +1,14 @@
- /*
- * jfdctint.c
- *
- * Copyright (C) 1991-1996, Thomas G. Lane.
- * This file is part of the Independent JPEG Group's software.
- * For conditions of distribution and use, see the accompanying README file.
- *
- * This file contains a slow-but-accurate integer implementation of the
- * forward DCT (Discrete Cosine Transform).
- *
- * A 2-D DCT can be done by 1-D DCT on each row followed by 1-D DCT
- * on each column. Direct algorithms are also available, but they are
- * much more complex and seem not to be any faster when reduced to code.
- *
- * This implementation is based on an algorithm described in
- * C. Loeffler, A. Ligtenberg and G. Moschytz, "Practical Fast 1-D DCT
- * Algorithms with 11 Multiplications", Proc. Int'l. Conf. on Acoustics,
- * Speech, and Signal Processing 1989 (ICASSP '89), pp. 988-991.
- * The primary algorithm described there uses 11 multiplies and 29 adds.
- * We use their alternate method with 12 multiplies and 32 adds.
- * The advantage of this method is that no data path contains more than one
- * multiplication; this allows a very simple and accurate implementation in
- * scaled fixed-point arithmetic, with a minimal number of shifts.
- */
-/*
-#define JPEG_INTERNALS
-#include "jinclude.h"
-#include "jpeglib.h"
-
-*/
#include "dct.h" /* Private declarations for DCT subsystem */
#define DCTSIZE 8
#define INT32 int
-#ifdef RIGHT_SHIFT_IS_UNSIGNED
-#define SHIFT_TEMPS INT32 shift_temp;
-#define RIGHT_SHIFT(x,shft) \
- ((shift_temp = (x)) < 0 ? \
- (shift_temp >> (shft)) | ((~((INT32) 0)) << (32-(shft))) : \
- (shift_temp >> (shft)))
-#else
-#define SHIFT_TEMPSy
-#define RIGHT_SHIFT(x,shft) ((x) >> (shft))
-#endif
-
-#ifndef USE_ACCURATE_ROUNDING
-#undef DESCALE
-#define DESCALE(x,n) RIGHT_SHIFT(x, n)
-#endif
-
-
-
-/*
- * This module is specialized to the case DCTSIZE = 8.
- */
-
-#if DCTSIZE != 8
- Sorry, this code only copes with 8x8 DCTs. /* deliberate syntax err */
-#endif
-
-/*
- * The poop on this scaling stuff is as follows:
- *
- * Each 1-D DCT step produces outputs which are a factor of sqrt(N)
- * larger than the true DCT outputs. The final outputs are therefore
- * a factor of N larger than desired; since N=8 this can be cured by
- * a simple right shift at the end of the algorithm. The advantage of
- * this arrangement is that we save two multiplications per 1-D DCT,
- * because the y0 and y4 outputs need not be divided by sqrt(N).
- * In the IJG code, this factor of 8 is removed by the quantization step
- * (in jcdctmgr.c), NOT in this module.
- *
- * We have to do addition and subtraction of the integer inputs, which
- * is no problem, and multiplication by fractional constants, which is
- * a problem to do in integer arithmetic. We multiply all the constants
- * by CONST_SCALE and convert them to integer constants (thus retaining
- * CONST_BITS bits of precision in the constants). After doing a
- * multiplication we have to divide the product by CONST_SCALE, with proper
- * rounding, to produce the correct output. This division can be done
- * cheaply as a right shift of CONST_BITS bits. We postpone shifting
- * as long as possible so that partial sums can be added together with
- * full fractional precision.
- *
- * The outputs of the first pass are scaled up by PASS1_BITS bits so that
- * they are represented to better-than-integral precision. These outputs
- * require BITS_IN_JSAMPLE + PASS1_BITS + 3 bits; this fits in a 16-bit word
- * with the recommended scaling. (For 12-bit sample data, the intermediate
- * array is INT32 anyway.)
- *
- * To avoid overflow of the 32-bit intermediate results in pass 2, we must
- * have BITS_IN_JSAMPLE + CONST_BITS + PASS1_BITS <= 26. Error analysis
- * shows that the values given below are the most effective.
- */
+#define DESCALE(x,shft) ((x) >> (shft))
+#define MULTIPLY(var,const) ((var) * (const))
-#if BITS_IN_JSAMPLE == 8
-#define CONST_BITS 13
-#define PASS1_BITS 2
-#else
#define CONST_BITS 13
#define PASS1_BITS 1 /* lose a little precision to avoid overflow */
-#endif
-
-/* Some C compilers fail to reduce "FIX(constant)" at compile time, thus
- * causing a lot of useless floating-point operations at run time.
- * To get around this we use the following pre-calculated constants.
- * If you change CONST_BITS you may want to add appropriate values.
- * (With a reasonable C compiler, you can just rely on the FIX() macro...)
- */
-#if CONST_BITS == 13
#define FIX_0_298631336 ((INT32) 2446) /* FIX(0.298631336) */
#define FIX_0_390180644 ((INT32) 3196) /* FIX(0.390180644) */
#define FIX_0_541196100 ((INT32) 4433) /* FIX(0.541196100) */
@@ -121,43 +21,12 @@
#define FIX_2_053119869 ((INT32) 16819) /* FIX(2.053119869) */
#define FIX_2_562915447 ((INT32) 20995) /* FIX(2.562915447) */
#define FIX_3_072711026 ((INT32) 25172) /* FIX(3.072711026) */
-#else
-#define FIX_0_298631336 FIX(0.298631336)
-#define FIX_0_390180644 FIX(0.390180644)
-#define FIX_0_541196100 FIX(0.541196100)
-#define FIX_0_765366865 FIX(0.765366865)
-#define FIX_0_899976223 FIX(0.899976223)
-#define FIX_1_175875602 FIX(1.175875602)
-#define FIX_1_501321110 FIX(1.501321110)
-#define FIX_1_847759065 FIX(1.847759065)
-#define FIX_1_961570560 FIX(1.961570560)
-#define FIX_2_053119869 FIX(2.053119869)
-#define FIX_2_562915447 FIX(2.562915447)
-#define FIX_3_072711026 FIX(3.072711026)
-#endif
-
-
-/* Multiply an INT32 variable by an INT32 constant to yield an INT32 result.
- * For 8-bit samples with the recommended scaling, all the variable
- * and constant values involved are no more than 16 bits wide, so a
- * 16x16->32 bit multiply can be used instead of a full 32x32 multiply.
- * For 12-bit samples, a full 32-bit multiplication will be needed.
- */
-
-#if BITS_IN_JSAMPLE == 8
-#define MULTIPLY(var,const) MULTIPLY16C16(var,const)
-#else
-#define MULTIPLY(var,const) ((var) * (const))
-#endif
/*
* Perform the forward DCT on one block of samples.
*/
-//GLOBAL(void)
-//jpeg_fdct_islow (DCTELEM * data)
-//
void jpeg_fdct_ifast (DCTELEM * data)
{
INT32 tmp0, tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7;
@@ -181,36 +50,36 @@ void jpeg_fdct_ifast (DCTELEM * data)
tmp5 = dataptr[2] - dataptr[5];
tmp3 = dataptr[3] + dataptr[4];
tmp4 = dataptr[3] - dataptr[4];
-
+
/* Even part per LL&M figure 1 --- note that published figure is faulty;
* rotator "sqrt(2)*c1" should be "sqrt(2)*c6".
*/
-
+
tmp10 = tmp0 + tmp3;
tmp13 = tmp0 - tmp3;
tmp11 = tmp1 + tmp2;
tmp12 = tmp1 - tmp2;
-
+
dataptr[0] = (DCTELEM) ((tmp10 + tmp11) << PASS1_BITS);
dataptr[4] = (DCTELEM) ((tmp10 - tmp11) << PASS1_BITS);
-
+
z1 = MULTIPLY(tmp12 + tmp13, FIX_0_541196100);
dataptr[2] = (DCTELEM) DESCALE(z1 + MULTIPLY(tmp13, FIX_0_765366865),
CONST_BITS-PASS1_BITS);
dataptr[6] = (DCTELEM) DESCALE(z1 + MULTIPLY(tmp12, - FIX_1_847759065),
CONST_BITS-PASS1_BITS);
-
+
/* Odd part per figure 8 --- note paper omits factor of sqrt(2).
* cK represents cos(K*pi/16).
* i0..i3 in the paper are tmp4..tmp7 here.
*/
-
+
z1 = tmp4 + tmp7;
z2 = tmp5 + tmp6;
z3 = tmp4 + tmp6;
z4 = tmp5 + tmp7;
z5 = MULTIPLY(z3 + z4, FIX_1_175875602); /* sqrt(2) * c3 */
-
+
tmp4 = MULTIPLY(tmp4, FIX_0_298631336); /* sqrt(2) * (-c1+c3+c5-c7) */
tmp5 = MULTIPLY(tmp5, FIX_2_053119869); /* sqrt(2) * ( c1+c3-c5+c7) */
tmp6 = MULTIPLY(tmp6, FIX_3_072711026); /* sqrt(2) * ( c1+c3+c5-c7) */
@@ -219,15 +88,15 @@ void jpeg_fdct_ifast (DCTELEM * data)
z2 = MULTIPLY(z2, - FIX_2_562915447); /* sqrt(2) * (-c1-c3) */
z3 = MULTIPLY(z3, - FIX_1_961570560); /* sqrt(2) * (-c3-c5) */
z4 = MULTIPLY(z4, - FIX_0_390180644); /* sqrt(2) * (c5-c3) */
-
+
z3 += z5;
z4 += z5;
-
+
dataptr[7] = (DCTELEM) DESCALE(tmp4 + z1 + z3, CONST_BITS-PASS1_BITS);
dataptr[5] = (DCTELEM) DESCALE(tmp5 + z2 + z4, CONST_BITS-PASS1_BITS);
dataptr[3] = (DCTELEM) DESCALE(tmp6 + z2 + z3, CONST_BITS-PASS1_BITS);
dataptr[1] = (DCTELEM) DESCALE(tmp7 + z1 + z4, CONST_BITS-PASS1_BITS);
-
+
dataptr += DCTSIZE; /* advance pointer to next row */
}
@@ -246,36 +115,36 @@ void jpeg_fdct_ifast (DCTELEM * data)
tmp5 = dataptr[DCTSIZE*2] - dataptr[DCTSIZE*5];
tmp3 = dataptr[DCTSIZE*3] + dataptr[DCTSIZE*4];
tmp4 = dataptr[DCTSIZE*3] - dataptr[DCTSIZE*4];
-
+
/* Even part per LL&M figure 1 --- note that published figure is faulty;
* rotator "sqrt(2)*c1" should be "sqrt(2)*c6".
*/
-
+
tmp10 = tmp0 + tmp3;
tmp13 = tmp0 - tmp3;
tmp11 = tmp1 + tmp2;
tmp12 = tmp1 - tmp2;
-
+
dataptr[DCTSIZE*0] = (DCTELEM) DESCALE(tmp10 + tmp11, PASS1_BITS);
dataptr[DCTSIZE*4] = (DCTELEM) DESCALE(tmp10 - tmp11, PASS1_BITS);
-
+
z1 = MULTIPLY(tmp12 + tmp13, FIX_0_541196100);
dataptr[DCTSIZE*2] = (DCTELEM) DESCALE(z1 + MULTIPLY(tmp13, FIX_0_765366865),
CONST_BITS+PASS1_BITS);
dataptr[DCTSIZE*6] = (DCTELEM) DESCALE(z1 + MULTIPLY(tmp12, - FIX_1_847759065),
CONST_BITS+PASS1_BITS);
-
+
/* Odd part per figure 8 --- note paper omits factor of sqrt(2).
* cK represents cos(K*pi/16).
* i0..i3 in the paper are tmp4..tmp7 here.
*/
-
+
z1 = tmp4 + tmp7;
z2 = tmp5 + tmp6;
z3 = tmp4 + tmp6;
z4 = tmp5 + tmp7;
z5 = MULTIPLY(z3 + z4, FIX_1_175875602); /* sqrt(2) * c3 */
-
+
tmp4 = MULTIPLY(tmp4, FIX_0_298631336); /* sqrt(2) * (-c1+c3+c5-c7) */
tmp5 = MULTIPLY(tmp5, FIX_2_053119869); /* sqrt(2) * ( c1+c3-c5+c7) */
tmp6 = MULTIPLY(tmp6, FIX_3_072711026); /* sqrt(2) * ( c1+c3+c5-c7) */
@@ -284,19 +153,15 @@ void jpeg_fdct_ifast (DCTELEM * data)
z2 = MULTIPLY(z2, - FIX_2_562915447); /* sqrt(2) * (-c1-c3) */
z3 = MULTIPLY(z3, - FIX_1_961570560); /* sqrt(2) * (-c3-c5) */
z4 = MULTIPLY(z4, - FIX_0_390180644); /* sqrt(2) * (c5-c3) */
-
+
z3 += z5;
z4 += z5;
-
- dataptr[DCTSIZE*7] = (DCTELEM) DESCALE(tmp4 + z1 + z3,
- CONST_BITS+PASS1_BITS);
- dataptr[DCTSIZE*5] = (DCTELEM) DESCALE(tmp5 + z2 + z4,
- CONST_BITS+PASS1_BITS);
- dataptr[DCTSIZE*3] = (DCTELEM) DESCALE(tmp6 + z2 + z3,
- CONST_BITS+PASS1_BITS);
- dataptr[DCTSIZE*1] = (DCTELEM) DESCALE(tmp7 + z1 + z4,
- CONST_BITS+PASS1_BITS);
-
+
+ dataptr[DCTSIZE*7] = (DCTELEM) DESCALE(tmp4 + z1 + z3, CONST_BITS+PASS1_BITS);
+ dataptr[DCTSIZE*5] = (DCTELEM) DESCALE(tmp5 + z2 + z4, CONST_BITS+PASS1_BITS);
+ dataptr[DCTSIZE*3] = (DCTELEM) DESCALE(tmp6 + z2 + z3, CONST_BITS+PASS1_BITS);
+ dataptr[DCTSIZE*1] = (DCTELEM) DESCALE(tmp7 + z1 + z4, CONST_BITS+PASS1_BITS);
+
dataptr++; /* advance pointer to next column */
}
}
diff --git a/src/idct.c b/src/idct.c
index db83be8..fce305a 100644
--- a/src/idct.c
+++ b/src/idct.c
@@ -3,7 +3,7 @@
/* Author : Pierre Guerrier, march 1998 */
/* IDCT code by Geert Janssen */
/*---------------------------------------------*/
-#include "idct.h"
+#include "dct.h"
/*-------------------------------------------------------*/
/* JPEG data types here */