4 * Copyright (C) 2007 Marc Hoffman <marc.hoffman@analog.com>
6 * This file is part of FFmpeg.
8 * FFmpeg is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; either
11 * version 2.1 of the License, or (at your option) any later version.
13 * FFmpeg is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Lesser General Public License for more details.
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with FFmpeg; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
23 void ff_bfin_fdct (int16_t *buf);
25 This implementation works only for 8x8 input. The range of input
26 must be -256 to 255 i.e. 8bit input represented in a 16bit data
27 word. The original data must be sign extended into the 16bit data
34 X(m) = sum (x(n) * cos ((2n+1)*m*pi/16))
38 0 --*-------------*0+7---*-----*0+3-------*-*-------------------> 0
40 1 --*-\---------/-*1+6---*-\-/-*1+2-------*-*-------------------> 4
42 2 --*---\-----/---*2+5---*-/-\-*1-2---------------*-*-----------> 2
44 3 --*-----\-/-----*3+4---*-----*0-3---------------*-*-----------> 6
46 4 --*-----/-\-----*3-4------------*-*4+5--*-----*---------------> 1
48 5 --*---/-----\---*2-5---*-*------*=*4-5----\-/------*-*--------> 5
49 / \ X S4,S4 / X S3,-S3
50 6 --*-/---------\-*1-6---*-*------*=*7-6----/-\------*-*--------> 3
52 --*-------------*0-7------------*-*7+6--*-----*---------------> 7
56 Cn = cos(n*pi/8) used throughout the code.
60 R0, R1, R2, R3, R4, R5, R6,R7, P0, P1, P2, P3, P4, P5, A0, A1.
62 I0, I1, I2, I3, B0, B2, B3, M0, M1, L3 registers and LC0.
64 Input - r0 - pointer to start of int16_t *block
66 Output - The DCT output coefficients in the int16_t *block
69 This code is called from jpeg_encode.
70 R6, R5, R4 if modified should be stored and restored.
73 Performance: (Timer version 0.6.33)
74 Code Size : 240 Bytes.
76 Input Matrix : 8 * 8 * 2 Bytes.
77 Coefficients : 16 Bytes
78 Temporary matrix: 8 * 8 * 2 Bytes.
79 Cycle Count :26+{18+8*(14+2S)}*2 where S -> Stalls
81 -----------------------------------------
82 | Size | Forward DCT | Inverse DCT |
83 -----------------------------------------
84 | 8x8 | 284 Cycles | 311 Cycles |
85 -----------------------------------------
87 Ck = int16(cos(k/16*pi)*32767+.5)/2
93 Sk = int16(sin(k/16*pi)*32767+.5)/2
99 the coefficients are ordered as follows:
106 -----------------------------------------------------------
107 FFMPEG conformance testing results
108 -----------------------------------------------------------
109 dct-test: modified with the following
110 dct_error("BFINfdct", 0, ff_bfin_fdct, fdct, test);
111 produces the following output:
113 root:/u/ffmpeg/bhead/libavcodec> ./dct-test
116 2 -131 -6 -48 -36 33 -83 24
117 34 52 -24 -15 5 92 57 143
118 -67 -43 -1 74 -16 5 -71 32
119 -78 106 92 -34 -38 81 20 -18
120 7 -62 40 2 -15 90 -62 -83
121 -83 1 -104 -13 43 -19 7 11
122 -63 31 12 -29 83 72 21 10
123 -17 -63 -15 73 50 -91 159 -14
124 DCT BFINfdct: err_inf=2 err2=0.16425938 syserr=0.00795000 maxout=2098 blockSumErr=27
125 DCT BFINfdct: 92.1 kdct/s
126 root:/u/ffmpeg/bhead/libavcodec>
130 #include "libavutil/bfin/asm.h"
136 .short 0x5a82, 0x2d41, 0x187e, 0x3b21, 0x0c7c, 0x3ec5, 0x238e, 0x3537;
146 [--SP] = (R7:4, P5:3); // Push the registers onto the stack.
149 RELOC(r0, P3, dct_coeff);
154 L3 = 16; // L3 is set to 16 to make the coefficient
158 //----------------------------------------------------------------------------
161 * I0, I1, and I2 registers are used to read the input data. I3 register is used
162 * to read the coefficients. P0 and P1 registers are used for writing the output
165 M0 = 12 (X); // All these initializations are used in the
166 M1 = 16 (X); // modification of address offsets.
177 // Prescale the input to get the correct precision.
181 lsetup (.0, .1) LC0 = P3;
183 .0: r1=r0<<3 (v) || r0=[i0++] ;
187 * B0 points to the "in" buffer.
188 * B2 points to "temp" buffer in the first iteration.
191 lsetup (.2, .3) LC0 = P0;
193 I0 = B0; // I0 points to Input Element (0, 0).
194 I1 = B0; // Element 1 and 0 is read in R0.
195 I1 += M0 || R0 = [I0++]; // I1 points to Input Element (0, 6).
196 I2 = I1; // Element 6 is read into R3.H.
197 I2 -= 4 || R3.H = W[I1++]; // I2 points to Input Element (0, 4).
199 I3 = B3; // I3 points to Coefficients.
200 P0 = B2; // P0 points to temporary array Element
202 P1 = B2; // P1 points to temporary array.
203 R7 = [P1++P2] || R2 = [I2++]; // P1 points to temporary array
205 // R7 is a dummy read. X4,X5
207 R3.L = W[I1--]; // X7 is read into R3.L.
208 R1.H = W[I0++]; // X2 is read into R1.H.
212 * X0 = (X0 + X7) / 2.
213 * X1 = (X1 + X6) / 2.
214 * X6 = (X1 - X6) / 2.
215 * X7 = (X0 - X7) / 2.
216 * It reads the data 3 in R1.L.
219 R0 = R0 +|+ R3, R3 = R0 -|- R3 || R1.L = W[I0++] || NOP;
222 * X2 = (X2 + X5) / 2.
223 * X3 = (X3 + X4) / 2.
224 * X4 = (X3 - X4) / 2.
225 * X5 = (X2 - X5) / 2.
226 * R7 = C4 = cos(4*pi/16)
229 R1 = R1 +|+ R2, R2 = R1 -|- R2 (CO) || NOP || R7 = [I3++];
232 * At the end of stage 1 R0 has (1,0), R1 has (2,3), R2 has (4, 5) and
234 * Where the notation (x, y) represents uper/lower half pairs.
243 R0 = R0 +|+ R1, R1 = R0 -|- R1;
245 lsetup (.row0, .row1) LC1 = P2 >> 1; // 1d dct, loops 8x
249 * This is part 2 computation continued.....
250 * A1 = X6 * cos(pi/4)
251 * A0 = X6 * cos(pi/4)
252 * A1 = A1 - X5 * cos(pi/4)
253 * A0 = A0 + X5 * cos(pi/4).
254 * The instruction W[I0] = R3.L is used for packing it to R2.L.
257 A1=R3.H*R7.l, A0=R3.H*R7.l || I1+=M1 || W[I0] = R3.L;
258 R4.H=(A1-=R2.L*R7.l), R4.L=(A0+=R2.L*R7.l) || I2+=M0 || NOP;
260 /* R0 = (X1,X0) R1 = (X2,X3) R4 = (X5, X6). */
263 * A1 = X0 * cos(pi/4)
264 * A0 = X0 * cos(pi/4)
265 * A1 = A1 - X1 * cos(pi/4)
266 * A0 = A0 + X1 * cos(pi/4)
269 A1=R0.L*R7.h, A0=R0.L*R7.h || NOP || R3.H=W[I1++];
270 R5.H=(A1-=R0.H*R7.h),R5.L=(A0+=R0.H*R7.h) || R7=[I3++] || NOP;
273 * A1 = X2 * cos(3pi/8)
274 * A0 = X3 * cos(3pi/8)
275 * A1 = A1 + X3 * cos(pi/8)
276 * A0 = A0 - X2 * cos(pi/8)
278 * R7 = (cos(7pi/8),cos(pi/8))
284 A1=R1.H*R7.L, A0=R1.L*R7.L || W[P0++P3]=R5.L || R2.L=W[I0];
285 R2=R2+|+R4, R4=R2-|-R4 || I0+=4 || R3.L=W[I1--];
286 R6.H=(A1+=R1.L*R7.H),R6.L=(A0 -= R1.H * R7.H) || I0+=4 || R7=[I3++];
288 /* R2 = (X4, X7) R4 = (X5,X6) R5 = (X1, X0) R6 = (X2,X3). */
291 * A1 = X4 * cos(7pi/16)
292 * A0 = X7 * cos(7pi/16)
293 * A1 = A1 + X7 * cos(pi/16)
294 * A0 = A0 - X4 * cos(pi/16)
297 A1=R2.H*R7.L, A0=R2.L*R7.L || W[P0++P3]=R6.H || R0=[I0++];
298 R2.H=(A1+=R2.L*R7.H),R2.L=(A0-=R2.H*R7.H) || W[P0++P3]=R5.H || R7=[I3++];
301 * A1 = X5 * cos(3pi/16)
302 * A0 = X6 * cos(3pi/16)
303 * A1 = A1 + X6 * cos(5pi/16)
304 * A0 = A0 - X5 * cos(5pi/16)
305 * The output values are written.
308 A1=R4.H*R7.H, A0=R4.L*R7.H || W[P0++P2]=R6.L || R1.H=W[I0++];
309 R4.H=(A1+=R4.L*R7.L),R4.L=(A0-=R4.H*R7.L) || W[P0++P4]=R2.L || R1.L=W[I0++];
312 /* Beginning of next stage, **pipelined** + drain and store the
313 rest of the column store. */
315 R0=R0+|+R3,R3=R0-|-R3 || W[P1++P3]=R2.H || R2=[I2++];
316 R1=R1+|+R2,R2=R1-|-R2 (CO) || W[P1++P3]=R4.L || R7=[I3++];
317 .row1: R0=R0+|+R1,R1=R0-|-R1 || W[P1++P5]=R4.H || NOP;
319 // Exchange input with output.
325 (r7:4,p5:3) = [sp++];