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Imported Debian version 2.4.3~trusty1
[deb_ffmpeg.git] / ffmpeg / libavcodec / arm / simple_idct_arm.S
CommitLineData
2ba45a60
DM		 1/*
2 * Copyright (C) 2002 Frederic 'dilb' Boulay
3 *
4 * Author: Frederic Boulay <dilb@handhelds.org>
5 *
6 * The function defined in this file is derived from the simple_idct function
7 * from the libavcodec library part of the FFmpeg project.
8 *
9 * This file is part of FFmpeg.
10 *
11 * FFmpeg is free software; you can redistribute it and/or
12 * modify it under the terms of the GNU Lesser General Public
13 * License as published by the Free Software Foundation; either
14 * version 2.1 of the License, or (at your option) any later version.
15 *
16 * FFmpeg is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
19 * Lesser General Public License for more details.
20 *
21 * You should have received a copy of the GNU Lesser General Public
22 * License along with FFmpeg; if not, write to the Free Software
23 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
24 */
25
26#include "libavutil/arm/asm.S"
27
28/* useful constants for the algorithm */
29#define W1 22725
30#define W2 21407
31#define W3 19266
32#define W4 16383
33#define W5 12873
34#define W6 8867
35#define W7 4520
36#define MASK_MSHW 0xFFFF0000
37
38#define ROW_SHIFT 11
39#define ROW_SHIFT2MSHW (16-11)
40#define COL_SHIFT 20
41#define ROW_SHIFTED_1 1024 /* 1<< (ROW_SHIFT-1) */
42#define COL_SHIFTED_1 524288 /* 1<< (COL_SHIFT-1) */
43
44
45function ff_simple_idct_arm, export=1
46 @@ void simple_idct_arm(int16_t *block)
47 @@ save stack for reg needed (take all of them),
48 @@ R0-R3 are scratch regs, so no need to save them, but R0 contains the pointer to block
49 @@ so it must not be overwritten, if it is not saved!!
50 @@ R12 is another scratch register, so it should not be saved too
51 @@ save all registers
52 stmfd sp!, {r4-r11, r14} @ R14 is also called LR
53 @@ at this point, R0=block, other registers are free.
54 add r14, r0, #112 @ R14=&block[8*7], better start from the last row, and decrease the value until row=0, i.e. R12=block.
55 @@ add 2 temporary variables in the stack: R0 and R14
56 sub sp, sp, #8 @ allow 2 local variables
57 str r0, [sp, #0] @ save block in sp[0]
58 @@ stack status
59 @@ sp+4 free
60 @@ sp+0 R0 (block)
61
62
63 @@ at this point, R0=block, R14=&block[56], R12=__const_ptr_, R1-R11 free
64
65
66__row_loop:
67 @@ read the row and check if it is null, almost null, or not, according to strongarm specs, it is not necessary to optimize ldr accesses (i.e. split 32bits in 2 16bits words), at least it gives more usable registers :)
68 ldr r1, [r14, #0] @ R1=(int32)(R12)[0]=ROWr32[0] (relative row cast to a 32b pointer)
69 ldr r2, [r14, #4] @ R2=(int32)(R12)[1]=ROWr32[1]
70 ldr r3, [r14, #8] @ R3=ROWr32[2]
71 ldr r4, [r14, #12] @ R4=ROWr32[3]
72 @@ check if the words are null, if all of them are null, then proceed with next row (branch __end_row_loop),
73 @@ if ROWr16[0] is the only one not null, then proceed with this special case (branch __almost_empty_row)
74 @@ else follow the complete algorithm.
75 @@ at this point, R0=block, R14=&block[n], R12=__const_ptr_, R1=ROWr32[0], R2=ROWr32[1],
76 @@ R3=ROWr32[2], R4=ROWr32[3], R5-R11 free
77 orr r5, r4, r3 @ R5=R4 | R3
78 orr r5, r5, r2 @ R5=R4 | R3 | R2
79 orrs r6, r5, r1 @ Test R5 | R1 (the aim is to check if everything is null)
80 beq __end_row_loop
81 mov r7, r1, asr #16 @ R7=R1>>16=ROWr16[1] (evaluate it now, as it could be useful later)
82 ldrsh r6, [r14, #0] @ R6=ROWr16[0]
83 orrs r5, r5, r7 @ R5=R4 | R3 | R2 | R7
84 beq __almost_empty_row
85
86@@ __b_evaluation:
87 @@ at this point, R0=block (temp), R1(free), R2=ROWr32[1], R3=ROWr32[2], R4=ROWr32[3],
88 @@ R5=(temp), R6=ROWr16[0], R7=ROWr16[1], R8-R11 free,
89 @@ R12=__const_ptr_, R14=&block[n]
90 @@ to save some registers/calls, proceed with b0-b3 first, followed by a0-a3
91
92 @@ MUL16(b0, W1, row[1]);
93 @@ MUL16(b1, W3, row[1]);
94 @@ MUL16(b2, W5, row[1]);
95 @@ MUL16(b3, W7, row[1]);
96 @@ MAC16(b0, W3, row[3]);
97 @@ MAC16(b1, -W7, row[3]);
98 @@ MAC16(b2, -W1, row[3]);
99 @@ MAC16(b3, -W5, row[3]);
100 ldr r8, =W1 @ R8=W1
101 mov r2, r2, asr #16 @ R2=ROWr16[3]
102 mul r0, r8, r7 @ R0=W1*ROWr16[1]=b0 (ROWr16[1] must be the second arg, to have the possibility to save 1 cycle)
103 ldr r9, =W3 @ R9=W3
104 ldr r10, =W5 @ R10=W5
105 mul r1, r9, r7 @ R1=W3*ROWr16[1]=b1 (ROWr16[1] must be the second arg, to have the possibility to save 1 cycle)
106 ldr r11, =W7 @ R11=W7
107 mul r5, r10, r7 @ R5=W5*ROWr16[1]=b2 (ROWr16[1] must be the second arg, to have the possibility to save 1 cycle)
108 mul r7, r11, r7 @ R7=W7*ROWr16[1]=b3 (ROWr16[1] must be the second arg, to have the possibility to save 1 cycle)
109 teq r2, #0 @ if null avoid muls
110 itttt ne
111 mlane r0, r9, r2, r0 @ R0+=W3*ROWr16[3]=b0 (ROWr16[3] must be the second arg, to have the possibility to save 1 cycle)
112 rsbne r2, r2, #0 @ R2=-ROWr16[3]
113 mlane r1, r11, r2, r1 @ R1-=W7*ROWr16[3]=b1 (ROWr16[3] must be the second arg, to have the possibility to save 1 cycle)
114 mlane r5, r8, r2, r5 @ R5-=W1*ROWr16[3]=b2 (ROWr16[3] must be the second arg, to have the possibility to save 1 cycle)
115 it ne
116 mlane r7, r10, r2, r7 @ R7-=W5*ROWr16[3]=b3 (ROWr16[3] must be the second arg, to have the possibility to save 1 cycle)
117
118 @@ at this point, R0=b0, R1=b1, R2 (free), R3=ROWr32[2], R4=ROWr32[3],
119 @@ R5=b2, R6=ROWr16[0], R7=b3, R8=W1, R9=W3, R10=W5, R11=W7,
120 @@ R12=__const_ptr_, R14=&block[n]
121 @@ temp = ((uint32_t*)row)[2] | ((uint32_t*)row)[3];
122 @@ if (temp != 0) {}
123 orrs r2, r3, r4 @ R2=ROWr32[2] | ROWr32[3]
124 beq __end_b_evaluation
125
126 @@ at this point, R0=b0, R1=b1, R2 (free), R3=ROWr32[2], R4=ROWr32[3],
127 @@ R5=b2, R6=ROWr16[0], R7=b3, R8=W1, R9=W3, R10=W5, R11=W7,
128 @@ R12=__const_ptr_, R14=&block[n]
129 @@ MAC16(b0, W5, row[5]);
130 @@ MAC16(b2, W7, row[5]);
131 @@ MAC16(b3, W3, row[5]);
132 @@ MAC16(b1, -W1, row[5]);
133 @@ MAC16(b0, W7, row[7]);
134 @@ MAC16(b2, W3, row[7]);
135 @@ MAC16(b3, -W1, row[7]);
136 @@ MAC16(b1, -W5, row[7]);
137 mov r3, r3, asr #16 @ R3=ROWr16[5]
138 teq r3, #0 @ if null avoid muls
139 it ne
140 mlane r0, r10, r3, r0 @ R0+=W5*ROWr16[5]=b0
141 mov r4, r4, asr #16 @ R4=ROWr16[7]
142 itttt ne
143 mlane r5, r11, r3, r5 @ R5+=W7*ROWr16[5]=b2
144 mlane r7, r9, r3, r7 @ R7+=W3*ROWr16[5]=b3
145 rsbne r3, r3, #0 @ R3=-ROWr16[5]
146 mlane r1, r8, r3, r1 @ R7-=W1*ROWr16[5]=b1
147 @@ R3 is free now
148 teq r4, #0 @ if null avoid muls
149 itttt ne
150 mlane r0, r11, r4, r0 @ R0+=W7*ROWr16[7]=b0
151 mlane r5, r9, r4, r5 @ R5+=W3*ROWr16[7]=b2
152 rsbne r4, r4, #0 @ R4=-ROWr16[7]
153 mlane r7, r8, r4, r7 @ R7-=W1*ROWr16[7]=b3
154 it ne
155 mlane r1, r10, r4, r1 @ R1-=W5*ROWr16[7]=b1
156 @@ R4 is free now
157__end_b_evaluation:
158 @@ at this point, R0=b0, R1=b1, R2=ROWr32[2] | ROWr32[3] (tmp), R3 (free), R4 (free),
159 @@ R5=b2, R6=ROWr16[0], R7=b3, R8 (free), R9 (free), R10 (free), R11 (free),
160 @@ R12=__const_ptr_, R14=&block[n]
161
162@@ __a_evaluation:
163 @@ a0 = (W4 * row[0]) + (1 << (ROW_SHIFT - 1));
164 @@ a1 = a0 + W6 * row[2];
165 @@ a2 = a0 - W6 * row[2];
166 @@ a3 = a0 - W2 * row[2];
167 @@ a0 = a0 + W2 * row[2];
168 ldr r9, =W4 @ R9=W4
169 mul r6, r9, r6 @ R6=W4*ROWr16[0]
170 ldr r10, =W6 @ R10=W6
171 ldrsh r4, [r14, #4] @ R4=ROWr16[2] (a3 not defined yet)
172 add r6, r6, #ROW_SHIFTED_1 @ R6=W4*ROWr16[0] + 1<<(ROW_SHIFT-1) (a0)
173
174 mul r11, r10, r4 @ R11=W6*ROWr16[2]
175 ldr r8, =W2 @ R8=W2
176 sub r3, r6, r11 @ R3=a0-W6*ROWr16[2] (a2)
177 @@ temp = ((uint32_t*)row)[2] | ((uint32_t*)row)[3];
178 @@ if (temp != 0) {}
179 teq r2, #0
180 beq __end_bef_a_evaluation
181
182 add r2, r6, r11 @ R2=a0+W6*ROWr16[2] (a1)
183 mul r11, r8, r4 @ R11=W2*ROWr16[2]
184 sub r4, r6, r11 @ R4=a0-W2*ROWr16[2] (a3)
185 add r6, r6, r11 @ R6=a0+W2*ROWr16[2] (a0)
186
187
188 @@ at this point, R0=b0, R1=b1, R2=a1, R3=a2, R4=a3,
189 @@ R5=b2, R6=a0, R7=b3, R8=W2, R9=W4, R10=W6, R11 (free),
190 @@ R12=__const_ptr_, R14=&block[n]
191
192
193 @@ a0 += W4*row[4]
194 @@ a1 -= W4*row[4]
195 @@ a2 -= W4*row[4]
196 @@ a3 += W4*row[4]
197 ldrsh r11, [r14, #8] @ R11=ROWr16[4]
198 teq r11, #0 @ if null avoid muls
199 it ne
200 mulne r11, r9, r11 @ R11=W4*ROWr16[4]
201 @@ R9 is free now
202 ldrsh r9, [r14, #12] @ R9=ROWr16[6]
203 itttt ne
204 addne r6, r6, r11 @ R6+=W4*ROWr16[4] (a0)
205 subne r2, r2, r11 @ R2-=W4*ROWr16[4] (a1)
206 subne r3, r3, r11 @ R3-=W4*ROWr16[4] (a2)
207 addne r4, r4, r11 @ R4+=W4*ROWr16[4] (a3)
208 @@ W6 alone is no more useful, save W2*ROWr16[6] in it instead
209 teq r9, #0 @ if null avoid muls
210 itttt ne
211 mulne r11, r10, r9 @ R11=W6*ROWr16[6]
212 addne r6, r6, r11 @ R6+=W6*ROWr16[6] (a0)
213 mulne r10, r8, r9 @ R10=W2*ROWr16[6]
214 @@ a0 += W6*row[6];
215 @@ a3 -= W6*row[6];
216 @@ a1 -= W2*row[6];
217 @@ a2 += W2*row[6];
218 subne r4, r4, r11 @ R4-=W6*ROWr16[6] (a3)
219 itt ne
220 subne r2, r2, r10 @ R2-=W2*ROWr16[6] (a1)
221 addne r3, r3, r10 @ R3+=W2*ROWr16[6] (a2)
222
223__end_a_evaluation:
224 @@ at this point, R0=b0, R1=b1, R2=a1, R3=a2, R4=a3,
225 @@ R5=b2, R6=a0, R7=b3, R8 (free), R9 (free), R10 (free), R11 (free),
226 @@ R12=__const_ptr_, R14=&block[n]
227 @@ row[0] = (a0 + b0) >> ROW_SHIFT;
228 @@ row[1] = (a1 + b1) >> ROW_SHIFT;
229 @@ row[2] = (a2 + b2) >> ROW_SHIFT;
230 @@ row[3] = (a3 + b3) >> ROW_SHIFT;
231 @@ row[4] = (a3 - b3) >> ROW_SHIFT;
232 @@ row[5] = (a2 - b2) >> ROW_SHIFT;
233 @@ row[6] = (a1 - b1) >> ROW_SHIFT;
234 @@ row[7] = (a0 - b0) >> ROW_SHIFT;
235 add r8, r6, r0 @ R8=a0+b0
236 add r9, r2, r1 @ R9=a1+b1
237 @@ put 2 16 bits half-words in a 32bits word
238 @@ ROWr32[0]=ROWr16[0] | (ROWr16[1]<<16) (only Little Endian compliant then!!!)
239 ldr r10, =MASK_MSHW @ R10=0xFFFF0000
240 and r9, r10, r9, lsl #ROW_SHIFT2MSHW @ R9=0xFFFF0000 & ((a1+b1)<<5)
241 mvn r11, r10 @ R11= NOT R10= 0x0000FFFF
242 and r8, r11, r8, asr #ROW_SHIFT @ R8=0x0000FFFF & ((a0+b0)>>11)
243 orr r8, r8, r9
244 str r8, [r14, #0]
245
246 add r8, r3, r5 @ R8=a2+b2
247 add r9, r4, r7 @ R9=a3+b3
248 and r9, r10, r9, lsl #ROW_SHIFT2MSHW @ R9=0xFFFF0000 & ((a3+b3)<<5)
249 and r8, r11, r8, asr #ROW_SHIFT @ R8=0x0000FFFF & ((a2+b2)>>11)
250 orr r8, r8, r9
251 str r8, [r14, #4]
252
253 sub r8, r4, r7 @ R8=a3-b3
254 sub r9, r3, r5 @ R9=a2-b2
255 and r9, r10, r9, lsl #ROW_SHIFT2MSHW @ R9=0xFFFF0000 & ((a2-b2)<<5)
256 and r8, r11, r8, asr #ROW_SHIFT @ R8=0x0000FFFF & ((a3-b3)>>11)
257 orr r8, r8, r9
258 str r8, [r14, #8]
259
260 sub r8, r2, r1 @ R8=a1-b1
261 sub r9, r6, r0 @ R9=a0-b0
262 and r9, r10, r9, lsl #ROW_SHIFT2MSHW @ R9=0xFFFF0000 & ((a0-b0)<<5)
263 and r8, r11, r8, asr #ROW_SHIFT @ R8=0x0000FFFF & ((a1-b1)>>11)
264 orr r8, r8, r9
265 str r8, [r14, #12]
266
267 bal __end_row_loop
268
269__almost_empty_row:
270 @@ the row was empty, except ROWr16[0], now, management of this special case
271 @@ at this point, R0=block, R14=&block[n], R12=__const_ptr_, R1=ROWr32[0], R2=ROWr32[1],
272 @@ R3=ROWr32[2], R4=ROWr32[3], R5=(temp), R6=ROWr16[0], R7=ROWr16[1],
273 @@ R8=0xFFFF (temp), R9-R11 free
274 mov r8, #0x10000 @ R8=0xFFFF (2 steps needed!) it saves a ldr call (because of delay run).
275 sub r8, r8, #1 @ R8 is now ready.
276 and r5, r8, r6, lsl #3 @ R5=R8 & (R6<<3)= (ROWr16[0]<<3) & 0xFFFF
277 orr r5, r5, r5, lsl #16 @ R5=R5 | (R5<<16)
278 str r5, [r14, #0] @ R14[0]=ROWr32[0]=R5
279 str r5, [r14, #4] @ R14[4]=ROWr32[1]=R5
280 str r5, [r14, #8] @ R14[8]=ROWr32[2]=R5
281 str r5, [r14, #12] @ R14[12]=ROWr32[3]=R5
282
283__end_row_loop:
284 @@ at this point, R0-R11 (free)
285 @@ R12=__const_ptr_, R14=&block[n]
286 ldr r0, [sp, #0] @ R0=block
287 teq r0, r14 @ compare current &block[8*n] to block, when block is reached, the loop is finished.
288 sub r14, r14, #16
289 bne __row_loop
290
291
292
293 @@ at this point, R0=block, R1-R11 (free)
294 @@ R12=__const_ptr_, R14=&block[n]
295 add r14, r0, #14 @ R14=&block[7], better start from the last col, and decrease the value until col=0, i.e. R14=block.
296__col_loop:
297
298@@ __b_evaluation2:
299 @@ at this point, R0=block (temp), R1-R11 (free)
300 @@ R12=__const_ptr_, R14=&block[n]
301 @@ proceed with b0-b3 first, followed by a0-a3
302 @@ MUL16(b0, W1, col[8x1]);
303 @@ MUL16(b1, W3, col[8x1]);
304 @@ MUL16(b2, W5, col[8x1]);
305 @@ MUL16(b3, W7, col[8x1]);
306 @@ MAC16(b0, W3, col[8x3]);
307 @@ MAC16(b1, -W7, col[8x3]);
308 @@ MAC16(b2, -W1, col[8x3]);
309 @@ MAC16(b3, -W5, col[8x3]);
310 ldr r8, =W1 @ R8=W1
311 ldrsh r7, [r14, #16]
312 mul r0, r8, r7 @ R0=W1*ROWr16[1]=b0 (ROWr16[1] must be the second arg, to have the possibility to save 1 cycle)
313 ldr r9, =W3 @ R9=W3
314 ldr r10, =W5 @ R10=W5
315 mul r1, r9, r7 @ R1=W3*ROWr16[1]=b1 (ROWr16[1] must be the second arg, to have the possibility to save 1 cycle)
316 ldr r11, =W7 @ R11=W7
317 mul r5, r10, r7 @ R5=W5*ROWr16[1]=b2 (ROWr16[1] must be the second arg, to have the possibility to save 1 cycle)
318 ldrsh r2, [r14, #48]
319 mul r7, r11, r7 @ R7=W7*ROWr16[1]=b3 (ROWr16[1] must be the second arg, to have the possibility to save 1 cycle)
320 teq r2, #0 @ if 0, then avoid muls
321 itttt ne
322 mlane r0, r9, r2, r0 @ R0+=W3*ROWr16[3]=b0 (ROWr16[3] must be the second arg, to have the possibility to save 1 cycle)
323 rsbne r2, r2, #0 @ R2=-ROWr16[3]
324 mlane r1, r11, r2, r1 @ R1-=W7*ROWr16[3]=b1 (ROWr16[3] must be the second arg, to have the possibility to save 1 cycle)
325 mlane r5, r8, r2, r5 @ R5-=W1*ROWr16[3]=b2 (ROWr16[3] must be the second arg, to have the possibility to save 1 cycle)
326 it ne
327 mlane r7, r10, r2, r7 @ R7-=W5*ROWr16[3]=b3 (ROWr16[3] must be the second arg, to have the possibility to save 1 cycle)
328
329 @@ at this point, R0=b0, R1=b1, R2 (free), R3 (free), R4 (free),
330 @@ R5=b2, R6 (free), R7=b3, R8=W1, R9=W3, R10=W5, R11=W7,
331 @@ R12=__const_ptr_, R14=&block[n]
332 @@ MAC16(b0, W5, col[5x8]);
333 @@ MAC16(b2, W7, col[5x8]);
334 @@ MAC16(b3, W3, col[5x8]);
335 @@ MAC16(b1, -W1, col[5x8]);
336 @@ MAC16(b0, W7, col[7x8]);
337 @@ MAC16(b2, W3, col[7x8]);
338 @@ MAC16(b3, -W1, col[7x8]);
339 @@ MAC16(b1, -W5, col[7x8]);
340 ldrsh r3, [r14, #80] @ R3=COLr16[5x8]
341 teq r3, #0 @ if 0 then avoid muls
342 itttt ne
343 mlane r0, r10, r3, r0 @ R0+=W5*ROWr16[5x8]=b0
344 mlane r5, r11, r3, r5 @ R5+=W7*ROWr16[5x8]=b2
345 mlane r7, r9, r3, r7 @ R7+=W3*ROWr16[5x8]=b3
346 rsbne r3, r3, #0 @ R3=-ROWr16[5x8]
347 ldrsh r4, [r14, #112] @ R4=COLr16[7x8]
348 it ne
349 mlane r1, r8, r3, r1 @ R7-=W1*ROWr16[5x8]=b1
350 @@ R3 is free now
351 teq r4, #0 @ if 0 then avoid muls
352 itttt ne
353 mlane r0, r11, r4, r0 @ R0+=W7*ROWr16[7x8]=b0
354 mlane r5, r9, r4, r5 @ R5+=W3*ROWr16[7x8]=b2
355 rsbne r4, r4, #0 @ R4=-ROWr16[7x8]
356 mlane r7, r8, r4, r7 @ R7-=W1*ROWr16[7x8]=b3
357 it ne
358 mlane r1, r10, r4, r1 @ R1-=W5*ROWr16[7x8]=b1
359 @@ R4 is free now
360@@ __end_b_evaluation2:
361 @@ at this point, R0=b0, R1=b1, R2 (free), R3 (free), R4 (free),
362 @@ R5=b2, R6 (free), R7=b3, R8 (free), R9 (free), R10 (free), R11 (free),
363 @@ R12=__const_ptr_, R14=&block[n]
364
365@@ __a_evaluation2:
366 @@ a0 = (W4 * col[8x0]) + (1 << (COL_SHIFT - 1));
367 @@ a1 = a0 + W6 * row[2];
368 @@ a2 = a0 - W6 * row[2];
369 @@ a3 = a0 - W2 * row[2];
370 @@ a0 = a0 + W2 * row[2];
371 ldrsh r6, [r14, #0]
372 ldr r9, =W4 @ R9=W4
373 mul r6, r9, r6 @ R6=W4*ROWr16[0]
374 ldr r10, =W6 @ R10=W6
375 ldrsh r4, [r14, #32] @ R4=ROWr16[2] (a3 not defined yet)
376 add r6, r6, #COL_SHIFTED_1 @ R6=W4*ROWr16[0] + 1<<(COL_SHIFT-1) (a0)
377 mul r11, r10, r4 @ R11=W6*ROWr16[2]
378 ldr r8, =W2 @ R8=W2
379 add r2, r6, r11 @ R2=a0+W6*ROWr16[2] (a1)
380 sub r3, r6, r11 @ R3=a0-W6*ROWr16[2] (a2)
381 mul r11, r8, r4 @ R11=W2*ROWr16[2]
382 sub r4, r6, r11 @ R4=a0-W2*ROWr16[2] (a3)
383 add r6, r6, r11 @ R6=a0+W2*ROWr16[2] (a0)
384
385 @@ at this point, R0=b0, R1=b1, R2=a1, R3=a2, R4=a3,
386 @@ R5=b2, R6=a0, R7=b3, R8=W2, R9=W4, R10=W6, R11 (free),
387 @@ R12=__const_ptr_, R14=&block[n]
388 @@ a0 += W4*row[4]
389 @@ a1 -= W4*row[4]
390 @@ a2 -= W4*row[4]
391 @@ a3 += W4*row[4]
392 ldrsh r11, [r14, #64] @ R11=ROWr16[4]
393 teq r11, #0 @ if null avoid muls
394 itttt ne
395 mulne r11, r9, r11 @ R11=W4*ROWr16[4]
396 @@ R9 is free now
397 addne r6, r6, r11 @ R6+=W4*ROWr16[4] (a0)
398 subne r2, r2, r11 @ R2-=W4*ROWr16[4] (a1)
399 subne r3, r3, r11 @ R3-=W4*ROWr16[4] (a2)
400 ldrsh r9, [r14, #96] @ R9=ROWr16[6]
401 it ne
402 addne r4, r4, r11 @ R4+=W4*ROWr16[4] (a3)
403 @@ W6 alone is no more useful, save W2*ROWr16[6] in it instead
404 teq r9, #0 @ if null avoid muls
405 itttt ne
406 mulne r11, r10, r9 @ R11=W6*ROWr16[6]
407 addne r6, r6, r11 @ R6+=W6*ROWr16[6] (a0)
408 mulne r10, r8, r9 @ R10=W2*ROWr16[6]
409 @@ a0 += W6*row[6];
410 @@ a3 -= W6*row[6];
411 @@ a1 -= W2*row[6];
412 @@ a2 += W2*row[6];
413 subne r4, r4, r11 @ R4-=W6*ROWr16[6] (a3)
414 itt ne
415 subne r2, r2, r10 @ R2-=W2*ROWr16[6] (a1)
416 addne r3, r3, r10 @ R3+=W2*ROWr16[6] (a2)
417@@ __end_a_evaluation2:
418 @@ at this point, R0=b0, R1=b1, R2=a1, R3=a2, R4=a3,
419 @@ R5=b2, R6=a0, R7=b3, R8 (free), R9 (free), R10 (free), R11 (free),
420 @@ R12=__const_ptr_, R14=&block[n]
421 @@ col[0 ] = ((a0 + b0) >> COL_SHIFT);
422 @@ col[8 ] = ((a1 + b1) >> COL_SHIFT);
423 @@ col[16] = ((a2 + b2) >> COL_SHIFT);
424 @@ col[24] = ((a3 + b3) >> COL_SHIFT);
425 @@ col[32] = ((a3 - b3) >> COL_SHIFT);
426 @@ col[40] = ((a2 - b2) >> COL_SHIFT);
427 @@ col[48] = ((a1 - b1) >> COL_SHIFT);
428 @@ col[56] = ((a0 - b0) >> COL_SHIFT);
429 @@@@@ no optimization here @@@@@
430 add r8, r6, r0 @ R8=a0+b0
431 add r9, r2, r1 @ R9=a1+b1
432 mov r8, r8, asr #COL_SHIFT
433 mov r9, r9, asr #COL_SHIFT
434 strh r8, [r14, #0]
435 strh r9, [r14, #16]
436 add r8, r3, r5 @ R8=a2+b2
437 add r9, r4, r7 @ R9=a3+b3
438 mov r8, r8, asr #COL_SHIFT
439 mov r9, r9, asr #COL_SHIFT
440 strh r8, [r14, #32]
441 strh r9, [r14, #48]
442 sub r8, r4, r7 @ R8=a3-b3
443 sub r9, r3, r5 @ R9=a2-b2
444 mov r8, r8, asr #COL_SHIFT
445 mov r9, r9, asr #COL_SHIFT
446 strh r8, [r14, #64]
447 strh r9, [r14, #80]
448 sub r8, r2, r1 @ R8=a1-b1
449 sub r9, r6, r0 @ R9=a0-b0
450 mov r8, r8, asr #COL_SHIFT
451 mov r9, r9, asr #COL_SHIFT
452 strh r8, [r14, #96]
453 strh r9, [r14, #112]
454
455@@ __end_col_loop:
456 @@ at this point, R0-R11 (free)
457 @@ R12=__const_ptr_, R14=&block[n]
458 ldr r0, [sp, #0] @ R0=block
459 teq r0, r14 @ compare current &block[n] to block, when block is reached, the loop is finished.
460 sub r14, r14, #2
461 bne __col_loop
462
463
464
465
466@@ __end_simple_idct_arm:
467 @@ restore registers to previous status!
468 add sp, sp, #8 @@ the local variables!
469 ldmfd sp!, {r4-r11, r15} @@ update PC with LR content.
470
471
472
473@@ kind of sub-function, here not to overload the common case.
474__end_bef_a_evaluation:
475 add r2, r6, r11 @ R2=a0+W6*ROWr16[2] (a1)
476 mul r11, r8, r4 @ R11=W2*ROWr16[2]
477 sub r4, r6, r11 @ R4=a0-W2*ROWr16[2] (a3)
478 add r6, r6, r11 @ R6=a0+W2*ROWr16[2] (a0)
479 bal __end_a_evaluation
480endfunc
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