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 (DCTELEM *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 DCTELEM *block
66 Output - The DCT output coefficients in the DCTELEM *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 "config_bfin.h"
133 .section .l1.data.B,"aw",@progbits
139 .short 0x5a82, 0x2d41, 0x187e, 0x3b21, 0x0c7c, 0x3ec5, 0x238e, 0x3537;
142 .section .l1.data.A,"aw",@progbits
150 [--SP] = (R7:4, P5:3); // Push the registers onto the stack.
153 RELOC(r0, P3, dct_coeff);
158 L3 = 16; // L3 is set to 16 to make the coefficient
162 //----------------------------------------------------------------------------
165 * I0, I1, and I2 registers are used to read the input data. I3 register is used
166 * to read the coefficients. P0 and P1 registers are used for writing the output
169 M0 = 12 (X); // All these initializations are used in the
170 M1 = 16 (X); // modification of address offsets.
181 // Prescale the input to get the correct precision.
185 lsetup (.0, .1) LC0 = P3;
187 .0: r1=r0<<3 (v) || r0=[i0++] ;
191 * B0 points to the "in" buffer.
192 * B2 points to "temp" buffer in the first iteration.
195 lsetup (.2, .3) LC0 = P0;
197 I0 = B0; // I0 points to Input Element (0, 0).
198 I1 = B0; // Element 1 and 0 is read in R0.
199 I1 += M0 || R0 = [I0++]; // I1 points to Input Element (0, 6).
200 I2 = I1; // Element 6 is read into R3.H.
201 I2 -= 4 || R3.H = W[I1++]; // I2 points to Input Element (0, 4).
203 I3 = B3; // I3 points to Coefficients.
204 P0 = B2; // P0 points to temporary array Element
206 P1 = B2; // P1 points to temporary array.
207 R7 = [P1++P2] || R2 = [I2++]; // P1 points to temporary array
209 // R7 is a dummy read. X4,X5
211 R3.L = W[I1--]; // X7 is read into R3.L.
212 R1.H = W[I0++]; // X2 is read into R1.H.
216 * X0 = (X0 + X7) / 2.
217 * X1 = (X1 + X6) / 2.
218 * X6 = (X1 - X6) / 2.
219 * X7 = (X0 - X7) / 2.
220 * It reads the data 3 in R1.L.
223 R0 = R0 +|+ R3, R3 = R0 -|- R3 || R1.L = W[I0++] || NOP;
226 * X2 = (X2 + X5) / 2.
227 * X3 = (X3 + X4) / 2.
228 * X4 = (X3 - X4) / 2.
229 * X5 = (X2 - X5) / 2.
230 * R7 = C4 = cos(4*pi/16)
233 R1 = R1 +|+ R2, R2 = R1 -|- R2 (CO) || NOP || R7 = [I3++];
236 * At the end of stage 1 R0 has (1,0), R1 has (2,3), R2 has (4, 5) and
238 * Where the notation (x, y) represents uper/lower half pairs.
247 R0 = R0 +|+ R1, R1 = R0 -|- R1;
249 lsetup (.row0, .row1) LC1 = P2 >> 1; // 1d dct, loops 8x
253 * This is part 2 computation continued.....
254 * A1 = X6 * cos(pi/4)
255 * A0 = X6 * cos(pi/4)
256 * A1 = A1 - X5 * cos(pi/4)
257 * A0 = A0 + X5 * cos(pi/4).
258 * The instruction W[I0] = R3.L is used for packing it to R2.L.
261 A1=R3.H*R7.l, A0=R3.H*R7.l || I1+=M1 || W[I0] = R3.L;
262 R4.H=(A1-=R2.L*R7.l), R4.L=(A0+=R2.L*R7.l) || I2+=M0 || NOP;
264 /* R0 = (X1,X0) R1 = (X2,X3) R4 = (X5, X6). */
267 * A1 = X0 * cos(pi/4)
268 * A0 = X0 * cos(pi/4)
269 * A1 = A1 - X1 * cos(pi/4)
270 * A0 = A0 + X1 * cos(pi/4)
273 A1=R0.L*R7.h, A0=R0.L*R7.h || NOP || R3.H=W[I1++];
274 R5.H=(A1-=R0.H*R7.h),R5.L=(A0+=R0.H*R7.h) || R7=[I3++] || NOP;
277 * A1 = X2 * cos(3pi/8)
278 * A0 = X3 * cos(3pi/8)
279 * A1 = A1 + X3 * cos(pi/8)
280 * A0 = A0 - X2 * cos(pi/8)
282 * R7 = (cos(7pi/8),cos(pi/8))
288 A1=R1.H*R7.L, A0=R1.L*R7.L || W[P0++P3]=R5.L || R2.L=W[I0];
289 R2=R2+|+R4, R4=R2-|-R4 || I0+=4 || R3.L=W[I1--];
290 R6.H=(A1+=R1.L*R7.H),R6.L=(A0 -= R1.H * R7.H) || I0+=4 || R7=[I3++];
292 /* R2 = (X4, X7) R4 = (X5,X6) R5 = (X1, X0) R6 = (X2,X3). */
295 * A1 = X4 * cos(7pi/16)
296 * A0 = X7 * cos(7pi/16)
297 * A1 = A1 + X7 * cos(pi/16)
298 * A0 = A0 - X4 * cos(pi/16)
301 A1=R2.H*R7.L, A0=R2.L*R7.L || W[P0++P3]=R6.H || R0=[I0++];
302 R2.H=(A1+=R2.L*R7.H),R2.L=(A0-=R2.H*R7.H) || W[P0++P3]=R5.H || R7=[I3++];
305 * A1 = X5 * cos(3pi/16)
306 * A0 = X6 * cos(3pi/16)
307 * A1 = A1 + X6 * cos(5pi/16)
308 * A0 = A0 - X5 * cos(5pi/16)
309 * The output values are written.
312 A1=R4.H*R7.H, A0=R4.L*R7.H || W[P0++P2]=R6.L || R1.H=W[I0++];
313 R4.H=(A1+=R4.L*R7.L),R4.L=(A0-=R4.H*R7.L) || W[P0++P4]=R2.L || R1.L=W[I0++];
316 /* Beginning of next stage, **pipelined** + drain and store the
317 rest of the column store. */
319 R0=R0+|+R3,R3=R0-|-R3 || W[P1++P3]=R2.H || R2=[I2++];
320 R1=R1+|+R2,R2=R1-|-R2 (CO) || W[P1++P3]=R4.L || R7=[I3++];
321 .row1: R0=R0+|+R1,R1=R0-|-R1 || W[P1++P5]=R4.H || NOP;
323 // Exchange input with output.
329 (r7:4,p5:3) = [sp++];