Doxygen Source Code Documentation
jfdctflt.c File Reference
#include "jinclude.h"
#include "jpeglib.h"
#include "jdct.h"
Go to the source code of this file.
Defines | |
#define | JPEG_INTERNALS |
Functions | |
jpeg_fdct_float (FAST_FLOAT *data) |
Define Documentation
|
Definition at line 37 of file jfdctflt.c. |
Function Documentation
|
Definition at line 59 of file jfdctflt.c. Referenced by jinit_forward_dct().
00060 { 00061 FAST_FLOAT tmp0, tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7; 00062 FAST_FLOAT tmp10, tmp11, tmp12, tmp13; 00063 FAST_FLOAT z1, z2, z3, z4, z5, z11, z13; 00064 FAST_FLOAT *dataptr; 00065 int ctr; 00066 00067 /* Pass 1: process rows. */ 00068 00069 dataptr = data; 00070 for (ctr = DCTSIZE-1; ctr >= 0; ctr--) { 00071 tmp0 = dataptr[0] + dataptr[7]; 00072 tmp7 = dataptr[0] - dataptr[7]; 00073 tmp1 = dataptr[1] + dataptr[6]; 00074 tmp6 = dataptr[1] - dataptr[6]; 00075 tmp2 = dataptr[2] + dataptr[5]; 00076 tmp5 = dataptr[2] - dataptr[5]; 00077 tmp3 = dataptr[3] + dataptr[4]; 00078 tmp4 = dataptr[3] - dataptr[4]; 00079 00080 /* Even part */ 00081 00082 tmp10 = tmp0 + tmp3; /* phase 2 */ 00083 tmp13 = tmp0 - tmp3; 00084 tmp11 = tmp1 + tmp2; 00085 tmp12 = tmp1 - tmp2; 00086 00087 dataptr[0] = tmp10 + tmp11; /* phase 3 */ 00088 dataptr[4] = tmp10 - tmp11; 00089 00090 z1 = (tmp12 + tmp13) * ((FAST_FLOAT) 0.707106781); /* c4 */ 00091 dataptr[2] = tmp13 + z1; /* phase 5 */ 00092 dataptr[6] = tmp13 - z1; 00093 00094 /* Odd part */ 00095 00096 tmp10 = tmp4 + tmp5; /* phase 2 */ 00097 tmp11 = tmp5 + tmp6; 00098 tmp12 = tmp6 + tmp7; 00099 00100 /* The rotator is modified from fig 4-8 to avoid extra negations. */ 00101 z5 = (tmp10 - tmp12) * ((FAST_FLOAT) 0.382683433); /* c6 */ 00102 z2 = ((FAST_FLOAT) 0.541196100) * tmp10 + z5; /* c2-c6 */ 00103 z4 = ((FAST_FLOAT) 1.306562965) * tmp12 + z5; /* c2+c6 */ 00104 z3 = tmp11 * ((FAST_FLOAT) 0.707106781); /* c4 */ 00105 00106 z11 = tmp7 + z3; /* phase 5 */ 00107 z13 = tmp7 - z3; 00108 00109 dataptr[5] = z13 + z2; /* phase 6 */ 00110 dataptr[3] = z13 - z2; 00111 dataptr[1] = z11 + z4; 00112 dataptr[7] = z11 - z4; 00113 00114 dataptr += DCTSIZE; /* advance pointer to next row */ 00115 } 00116 00117 /* Pass 2: process columns. */ 00118 00119 dataptr = data; 00120 for (ctr = DCTSIZE-1; ctr >= 0; ctr--) { 00121 tmp0 = dataptr[DCTSIZE*0] + dataptr[DCTSIZE*7]; 00122 tmp7 = dataptr[DCTSIZE*0] - dataptr[DCTSIZE*7]; 00123 tmp1 = dataptr[DCTSIZE*1] + dataptr[DCTSIZE*6]; 00124 tmp6 = dataptr[DCTSIZE*1] - dataptr[DCTSIZE*6]; 00125 tmp2 = dataptr[DCTSIZE*2] + dataptr[DCTSIZE*5]; 00126 tmp5 = dataptr[DCTSIZE*2] - dataptr[DCTSIZE*5]; 00127 tmp3 = dataptr[DCTSIZE*3] + dataptr[DCTSIZE*4]; 00128 tmp4 = dataptr[DCTSIZE*3] - dataptr[DCTSIZE*4]; 00129 00130 /* Even part */ 00131 00132 tmp10 = tmp0 + tmp3; /* phase 2 */ 00133 tmp13 = tmp0 - tmp3; 00134 tmp11 = tmp1 + tmp2; 00135 tmp12 = tmp1 - tmp2; 00136 00137 dataptr[DCTSIZE*0] = tmp10 + tmp11; /* phase 3 */ 00138 dataptr[DCTSIZE*4] = tmp10 - tmp11; 00139 00140 z1 = (tmp12 + tmp13) * ((FAST_FLOAT) 0.707106781); /* c4 */ 00141 dataptr[DCTSIZE*2] = tmp13 + z1; /* phase 5 */ 00142 dataptr[DCTSIZE*6] = tmp13 - z1; 00143 00144 /* Odd part */ 00145 00146 tmp10 = tmp4 + tmp5; /* phase 2 */ 00147 tmp11 = tmp5 + tmp6; 00148 tmp12 = tmp6 + tmp7; 00149 00150 /* The rotator is modified from fig 4-8 to avoid extra negations. */ 00151 z5 = (tmp10 - tmp12) * ((FAST_FLOAT) 0.382683433); /* c6 */ 00152 z2 = ((FAST_FLOAT) 0.541196100) * tmp10 + z5; /* c2-c6 */ 00153 z4 = ((FAST_FLOAT) 1.306562965) * tmp12 + z5; /* c2+c6 */ 00154 z3 = tmp11 * ((FAST_FLOAT) 0.707106781); /* c4 */ 00155 00156 z11 = tmp7 + z3; /* phase 5 */ 00157 z13 = tmp7 - z3; 00158 00159 dataptr[DCTSIZE*5] = z13 + z2; /* phase 6 */ 00160 dataptr[DCTSIZE*3] = z13 - z2; 00161 dataptr[DCTSIZE*1] = z11 + z4; 00162 dataptr[DCTSIZE*7] = z11 - z4; 00163 00164 dataptr++; /* advance pointer to next column */ 00165 } 00166 } |