1 | /* |
---|---|

2 | * jcdctmgr.c |

3 | * |

4 | * This file was part of the Independent JPEG Group's software: |

5 | * Copyright (C) 1994-1996, Thomas G. Lane. |

6 | * libjpeg-turbo Modifications: |

7 | * Copyright (C) 1999-2006, MIYASAKA Masaru. |

8 | * Copyright 2009 Pierre Ossman <ossman@cendio.se> for Cendio AB |

9 | * Copyright (C) 2011, 2014-2015, D. R. Commander. |

10 | * For conditions of distribution and use, see the accompanying README.ijg |

11 | * file. |

12 | * |

13 | * This file contains the forward-DCT management logic. |

14 | * This code selects a particular DCT implementation to be used, |

15 | * and it performs related housekeeping chores including coefficient |

16 | * quantization. |

17 | */ |

18 | |

19 | #define JPEG_INTERNALS |

20 | #include "jinclude.h" |

21 | #include "jpeglib.h" |

22 | #include "jdct.h" /* Private declarations for DCT subsystem */ |

23 | #include "jsimddct.h" |

24 | |

25 | |

26 | /* Private subobject for this module */ |

27 | |

28 | typedef void (*forward_DCT_method_ptr) (DCTELEM *data); |

29 | typedef void (*float_DCT_method_ptr) (FAST_FLOAT *data); |

30 | |

31 | typedef void (*convsamp_method_ptr) (JSAMPARRAY sample_data, |

32 | JDIMENSION start_col, |

33 | DCTELEM *workspace); |

34 | typedef void (*float_convsamp_method_ptr) (JSAMPARRAY sample_data, |

35 | JDIMENSION start_col, |

36 | FAST_FLOAT *workspace); |

37 | |

38 | typedef void (*quantize_method_ptr) (JCOEFPTR coef_block, DCTELEM *divisors, |

39 | DCTELEM *workspace); |

40 | typedef void (*float_quantize_method_ptr) (JCOEFPTR coef_block, |

41 | FAST_FLOAT *divisors, |

42 | FAST_FLOAT *workspace); |

43 | |

44 | METHODDEF(void) quantize (JCOEFPTR, DCTELEM *, DCTELEM *); |

45 | |

46 | typedef struct { |

47 | struct jpeg_forward_dct pub; /* public fields */ |

48 | |

49 | /* Pointer to the DCT routine actually in use */ |

50 | forward_DCT_method_ptr dct; |

51 | convsamp_method_ptr convsamp; |

52 | quantize_method_ptr quantize; |

53 | |

54 | /* The actual post-DCT divisors --- not identical to the quant table |

55 | * entries, because of scaling (especially for an unnormalized DCT). |

56 | * Each table is given in normal array order. |

57 | */ |

58 | DCTELEM *divisors[NUM_QUANT_TBLS]; |

59 | |

60 | /* work area for FDCT subroutine */ |

61 | DCTELEM *workspace; |

62 | |

63 | #ifdef DCT_FLOAT_SUPPORTED |

64 | /* Same as above for the floating-point case. */ |

65 | float_DCT_method_ptr float_dct; |

66 | float_convsamp_method_ptr float_convsamp; |

67 | float_quantize_method_ptr float_quantize; |

68 | FAST_FLOAT *float_divisors[NUM_QUANT_TBLS]; |

69 | FAST_FLOAT *float_workspace; |

70 | #endif |

71 | } my_fdct_controller; |

72 | |

73 | typedef my_fdct_controller *my_fdct_ptr; |

74 | |

75 | |

76 | #if BITS_IN_JSAMPLE == 8 |

77 | |

78 | /* |

79 | * Find the highest bit in an integer through binary search. |

80 | */ |

81 | |

82 | LOCAL(int) |

83 | flss (UINT16 val) |

84 | { |

85 | int bit; |

86 | |

87 | bit = 16; |

88 | |

89 | if (!val) |

90 | return 0; |

91 | |

92 | if (!(val & 0xff00)) { |

93 | bit -= 8; |

94 | val <<= 8; |

95 | } |

96 | if (!(val & 0xf000)) { |

97 | bit -= 4; |

98 | val <<= 4; |

99 | } |

100 | if (!(val & 0xc000)) { |

101 | bit -= 2; |

102 | val <<= 2; |

103 | } |

104 | if (!(val & 0x8000)) { |

105 | bit -= 1; |

106 | val <<= 1; |

107 | } |

108 | |

109 | return bit; |

110 | } |

111 | |

112 | |

113 | /* |

114 | * Compute values to do a division using reciprocal. |

115 | * |

116 | * This implementation is based on an algorithm described in |

117 | * "How to optimize for the Pentium family of microprocessors" |

118 | * (http://www.agner.org/assem/). |

119 | * More information about the basic algorithm can be found in |

120 | * the paper "Integer Division Using Reciprocals" by Robert Alverson. |

121 | * |

122 | * The basic idea is to replace x/d by x * d^-1. In order to store |

123 | * d^-1 with enough precision we shift it left a few places. It turns |

124 | * out that this algoright gives just enough precision, and also fits |

125 | * into DCTELEM: |

126 | * |

127 | * b = (the number of significant bits in divisor) - 1 |

128 | * r = (word size) + b |

129 | * f = 2^r / divisor |

130 | * |

131 | * f will not be an integer for most cases, so we need to compensate |

132 | * for the rounding error introduced: |

133 | * |

134 | * no fractional part: |

135 | * |

136 | * result = input >> r |

137 | * |

138 | * fractional part of f < 0.5: |

139 | * |

140 | * round f down to nearest integer |

141 | * result = ((input + 1) * f) >> r |

142 | * |

143 | * fractional part of f > 0.5: |

144 | * |

145 | * round f up to nearest integer |

146 | * result = (input * f) >> r |

147 | * |

148 | * This is the original algorithm that gives truncated results. But we |

149 | * want properly rounded results, so we replace "input" with |

150 | * "input + divisor/2". |

151 | * |

152 | * In order to allow SIMD implementations we also tweak the values to |

153 | * allow the same calculation to be made at all times: |

154 | * |

155 | * dctbl[0] = f rounded to nearest integer |

156 | * dctbl[1] = divisor / 2 (+ 1 if fractional part of f < 0.5) |

157 | * dctbl[2] = 1 << ((word size) * 2 - r) |

158 | * dctbl[3] = r - (word size) |

159 | * |

160 | * dctbl[2] is for stupid instruction sets where the shift operation |

161 | * isn't member wise (e.g. MMX). |

162 | * |

163 | * The reason dctbl[2] and dctbl[3] reduce the shift with (word size) |

164 | * is that most SIMD implementations have a "multiply and store top |

165 | * half" operation. |

166 | * |

167 | * Lastly, we store each of the values in their own table instead |

168 | * of in a consecutive manner, yet again in order to allow SIMD |

169 | * routines. |

170 | */ |

171 | |

172 | LOCAL(int) |

173 | compute_reciprocal (UINT16 divisor, DCTELEM *dtbl) |

174 | { |

175 | UDCTELEM2 fq, fr; |

176 | UDCTELEM c; |

177 | int b, r; |

178 | |

179 | if (divisor == 1) { |

180 | /* divisor == 1 means unquantized, so these reciprocal/correction/shift |

181 | * values will cause the C quantization algorithm to act like the |

182 | * identity function. Since only the C quantization algorithm is used in |

183 | * these cases, the scale value is irrelevant. |

184 | */ |

185 | dtbl[DCTSIZE2 * 0] = (DCTELEM) 1; /* reciprocal */ |

186 | dtbl[DCTSIZE2 * 1] = (DCTELEM) 0; /* correction */ |

187 | dtbl[DCTSIZE2 * 2] = (DCTELEM) 1; /* scale */ |

188 | dtbl[DCTSIZE2 * 3] = -(DCTELEM) (sizeof(DCTELEM) * 8); /* shift */ |

189 | return 0; |

190 | } |

191 | |

192 | b = flss(divisor) - 1; |

193 | r = sizeof(DCTELEM) * 8 + b; |

194 | |

195 | fq = ((UDCTELEM2)1 << r) / divisor; |

196 | fr = ((UDCTELEM2)1 << r) % divisor; |

197 | |

198 | c = divisor / 2; /* for rounding */ |

199 | |

200 | if (fr == 0) { /* divisor is power of two */ |

201 | /* fq will be one bit too large to fit in DCTELEM, so adjust */ |

202 | fq >>= 1; |

203 | r--; |

204 | } else if (fr <= (divisor / 2U)) { /* fractional part is < 0.5 */ |

205 | c++; |

206 | } else { /* fractional part is > 0.5 */ |

207 | fq++; |

208 | } |

209 | |

210 | dtbl[DCTSIZE2 * 0] = (DCTELEM) fq; /* reciprocal */ |

211 | dtbl[DCTSIZE2 * 1] = (DCTELEM) c; /* correction + roundfactor */ |

212 | #ifdef WITH_SIMD |

213 | dtbl[DCTSIZE2 * 2] = (DCTELEM) (1 << (sizeof(DCTELEM)*8*2 - r)); /* scale */ |

214 | #else |

215 | dtbl[DCTSIZE2 * 2] = 1; |

216 | #endif |

217 | dtbl[DCTSIZE2 * 3] = (DCTELEM) r - sizeof(DCTELEM)*8; /* shift */ |

218 | |

219 | if(r <= 16) return 0; |

220 | else return 1; |

221 | } |

222 | |

223 | #endif |

224 | |

225 | |

226 | /* |

227 | * Initialize for a processing pass. |

228 | * Verify that all referenced Q-tables are present, and set up |

229 | * the divisor table for each one. |

230 | * In the current implementation, DCT of all components is done during |

231 | * the first pass, even if only some components will be output in the |

232 | * first scan. Hence all components should be examined here. |

233 | */ |

234 | |

235 | METHODDEF(void) |

236 | start_pass_fdctmgr (j_compress_ptr cinfo) |

237 | { |

238 | my_fdct_ptr fdct = (my_fdct_ptr) cinfo->fdct; |

239 | int ci, qtblno, i; |

240 | jpeg_component_info *compptr; |

241 | JQUANT_TBL *qtbl; |

242 | DCTELEM *dtbl; |

243 | |

244 | for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; |

245 | ci++, compptr++) { |

246 | qtblno = compptr->quant_tbl_no; |

247 | /* Make sure specified quantization table is present */ |

248 | if (qtblno < 0 || qtblno >= NUM_QUANT_TBLS || |

249 | cinfo->quant_tbl_ptrs[qtblno] == NULL) |

250 | ERREXIT1(cinfo, JERR_NO_QUANT_TABLE, qtblno); |

251 | qtbl = cinfo->quant_tbl_ptrs[qtblno]; |

252 | /* Compute divisors for this quant table */ |

253 | /* We may do this more than once for same table, but it's not a big deal */ |

254 | switch (cinfo->dct_method) { |

255 | #ifdef DCT_ISLOW_SUPPORTED |

256 | case JDCT_ISLOW: |

257 | /* For LL&M IDCT method, divisors are equal to raw quantization |

258 | * coefficients multiplied by 8 (to counteract scaling). |

259 | */ |

260 | if (fdct->divisors[qtblno] == NULL) { |

261 | fdct->divisors[qtblno] = (DCTELEM *) |

262 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |

263 | (DCTSIZE2 * 4) * sizeof(DCTELEM)); |

264 | } |

265 | dtbl = fdct->divisors[qtblno]; |

266 | for (i = 0; i < DCTSIZE2; i++) { |

267 | #if BITS_IN_JSAMPLE == 8 |

268 | if (!compute_reciprocal(qtbl->quantval[i] << 3, &dtbl[i]) && |

269 | fdct->quantize == jsimd_quantize) |

270 | fdct->quantize = quantize; |

271 | #else |

272 | dtbl[i] = ((DCTELEM) qtbl->quantval[i]) << 3; |

273 | #endif |

274 | } |

275 | break; |

276 | #endif |

277 | #ifdef DCT_IFAST_SUPPORTED |

278 | case JDCT_IFAST: |

279 | { |

280 | /* For AA&N IDCT method, divisors are equal to quantization |

281 | * coefficients scaled by scalefactor[row]*scalefactor[col], where |

282 | * scalefactor[0] = 1 |

283 | * scalefactor[k] = cos(k*PI/16) * sqrt(2) for k=1..7 |

284 | * We apply a further scale factor of 8. |

285 | */ |

286 | #define CONST_BITS 14 |

287 | static const INT16 aanscales[DCTSIZE2] = { |

288 | /* precomputed values scaled up by 14 bits */ |

289 | 16384, 22725, 21407, 19266, 16384, 12873, 8867, 4520, |

290 | 22725, 31521, 29692, 26722, 22725, 17855, 12299, 6270, |

291 | 21407, 29692, 27969, 25172, 21407, 16819, 11585, 5906, |

292 | 19266, 26722, 25172, 22654, 19266, 15137, 10426, 5315, |

293 | 16384, 22725, 21407, 19266, 16384, 12873, 8867, 4520, |

294 | 12873, 17855, 16819, 15137, 12873, 10114, 6967, 3552, |

295 | 8867, 12299, 11585, 10426, 8867, 6967, 4799, 2446, |

296 | 4520, 6270, 5906, 5315, 4520, 3552, 2446, 1247 |

297 | }; |

298 | SHIFT_TEMPS |

299 | |

300 | if (fdct->divisors[qtblno] == NULL) { |

301 | fdct->divisors[qtblno] = (DCTELEM *) |

302 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |

303 | (DCTSIZE2 * 4) * sizeof(DCTELEM)); |

304 | } |

305 | dtbl = fdct->divisors[qtblno]; |

306 | for (i = 0; i < DCTSIZE2; i++) { |

307 | #if BITS_IN_JSAMPLE == 8 |

308 | if (!compute_reciprocal( |

309 | DESCALE(MULTIPLY16V16((JLONG) qtbl->quantval[i], |

310 | (JLONG) aanscales[i]), |

311 | CONST_BITS-3), &dtbl[i]) && |

312 | fdct->quantize == jsimd_quantize) |

313 | fdct->quantize = quantize; |

314 | #else |

315 | dtbl[i] = (DCTELEM) |

316 | DESCALE(MULTIPLY16V16((JLONG) qtbl->quantval[i], |

317 | (JLONG) aanscales[i]), |

318 | CONST_BITS-3); |

319 | #endif |

320 | } |

321 | } |

322 | break; |

323 | #endif |

324 | #ifdef DCT_FLOAT_SUPPORTED |

325 | case JDCT_FLOAT: |

326 | { |

327 | /* For float AA&N IDCT method, divisors are equal to quantization |

328 | * coefficients scaled by scalefactor[row]*scalefactor[col], where |

329 | * scalefactor[0] = 1 |

330 | * scalefactor[k] = cos(k*PI/16) * sqrt(2) for k=1..7 |

331 | * We apply a further scale factor of 8. |

332 | * What's actually stored is 1/divisor so that the inner loop can |

333 | * use a multiplication rather than a division. |

334 | */ |

335 | FAST_FLOAT *fdtbl; |

336 | int row, col; |

337 | static const double aanscalefactor[DCTSIZE] = { |

338 | 1.0, 1.387039845, 1.306562965, 1.175875602, |

339 | 1.0, 0.785694958, 0.541196100, 0.275899379 |

340 | }; |

341 | |

342 | if (fdct->float_divisors[qtblno] == NULL) { |

343 | fdct->float_divisors[qtblno] = (FAST_FLOAT *) |

344 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |

345 | DCTSIZE2 * sizeof(FAST_FLOAT)); |

346 | } |

347 | fdtbl = fdct->float_divisors[qtblno]; |

348 | i = 0; |

349 | for (row = 0; row < DCTSIZE; row++) { |

350 | for (col = 0; col < DCTSIZE; col++) { |

351 | fdtbl[i] = (FAST_FLOAT) |

352 | (1.0 / (((double) qtbl->quantval[i] * |

353 | aanscalefactor[row] * aanscalefactor[col] * 8.0))); |

354 | i++; |

355 | } |

356 | } |

357 | } |

358 | break; |

359 | #endif |

360 | default: |

361 | ERREXIT(cinfo, JERR_NOT_COMPILED); |

362 | break; |

363 | } |

364 | } |

365 | } |

366 | |

367 | |

368 | /* |

369 | * Load data into workspace, applying unsigned->signed conversion. |

370 | */ |

371 | |

372 | METHODDEF(void) |

373 | convsamp (JSAMPARRAY sample_data, JDIMENSION start_col, DCTELEM *workspace) |

374 | { |

375 | register DCTELEM *workspaceptr; |

376 | register JSAMPROW elemptr; |

377 | register int elemr; |

378 | |

379 | workspaceptr = workspace; |

380 | for (elemr = 0; elemr < DCTSIZE; elemr++) { |

381 | elemptr = sample_data[elemr] + start_col; |

382 | |

383 | #if DCTSIZE == 8 /* unroll the inner loop */ |

384 | *workspaceptr++ = GETJSAMPLE(*elemptr++) - CENTERJSAMPLE; |

385 | *workspaceptr++ = GETJSAMPLE(*elemptr++) - CENTERJSAMPLE; |

386 | *workspaceptr++ = GETJSAMPLE(*elemptr++) - CENTERJSAMPLE; |

387 | *workspaceptr++ = GETJSAMPLE(*elemptr++) - CENTERJSAMPLE; |

388 | *workspaceptr++ = GETJSAMPLE(*elemptr++) - CENTERJSAMPLE; |

389 | *workspaceptr++ = GETJSAMPLE(*elemptr++) - CENTERJSAMPLE; |

390 | *workspaceptr++ = GETJSAMPLE(*elemptr++) - CENTERJSAMPLE; |

391 | *workspaceptr++ = GETJSAMPLE(*elemptr++) - CENTERJSAMPLE; |

392 | #else |

393 | { |

394 | register int elemc; |

395 | for (elemc = DCTSIZE; elemc > 0; elemc--) |

396 | *workspaceptr++ = GETJSAMPLE(*elemptr++) - CENTERJSAMPLE; |

397 | } |

398 | #endif |

399 | } |

400 | } |

401 | |

402 | |

403 | /* |

404 | * Quantize/descale the coefficients, and store into coef_blocks[]. |

405 | */ |

406 | |

407 | METHODDEF(void) |

408 | quantize (JCOEFPTR coef_block, DCTELEM *divisors, DCTELEM *workspace) |

409 | { |

410 | int i; |

411 | DCTELEM temp; |

412 | JCOEFPTR output_ptr = coef_block; |

413 | |

414 | #if BITS_IN_JSAMPLE == 8 |

415 | |

416 | UDCTELEM recip, corr; |

417 | int shift; |

418 | UDCTELEM2 product; |

419 | |

420 | for (i = 0; i < DCTSIZE2; i++) { |

421 | temp = workspace[i]; |

422 | recip = divisors[i + DCTSIZE2 * 0]; |

423 | corr = divisors[i + DCTSIZE2 * 1]; |

424 | shift = divisors[i + DCTSIZE2 * 3]; |

425 | |

426 | if (temp < 0) { |

427 | temp = -temp; |

428 | product = (UDCTELEM2)(temp + corr) * recip; |

429 | product >>= shift + sizeof(DCTELEM)*8; |

430 | temp = (DCTELEM)product; |

431 | temp = -temp; |

432 | } else { |

433 | product = (UDCTELEM2)(temp + corr) * recip; |

434 | product >>= shift + sizeof(DCTELEM)*8; |

435 | temp = (DCTELEM)product; |

436 | } |

437 | output_ptr[i] = (JCOEF) temp; |

438 | } |

439 | |

440 | #else |

441 | |

442 | register DCTELEM qval; |

443 | |

444 | for (i = 0; i < DCTSIZE2; i++) { |

445 | qval = divisors[i]; |

446 | temp = workspace[i]; |

447 | /* Divide the coefficient value by qval, ensuring proper rounding. |

448 | * Since C does not specify the direction of rounding for negative |

449 | * quotients, we have to force the dividend positive for portability. |

450 | * |

451 | * In most files, at least half of the output values will be zero |

452 | * (at default quantization settings, more like three-quarters...) |

453 | * so we should ensure that this case is fast. On many machines, |

454 | * a comparison is enough cheaper than a divide to make a special test |

455 | * a win. Since both inputs will be nonnegative, we need only test |

456 | * for a < b to discover whether a/b is 0. |

457 | * If your machine's division is fast enough, define FAST_DIVIDE. |

458 | */ |

459 | #ifdef FAST_DIVIDE |

460 | #define DIVIDE_BY(a,b) a /= b |

461 | #else |

462 | #define DIVIDE_BY(a,b) if (a >= b) a /= b; else a = 0 |

463 | #endif |

464 | if (temp < 0) { |

465 | temp = -temp; |

466 | temp += qval>>1; /* for rounding */ |

467 | DIVIDE_BY(temp, qval); |

468 | temp = -temp; |

469 | } else { |

470 | temp += qval>>1; /* for rounding */ |

471 | DIVIDE_BY(temp, qval); |

472 | } |

473 | output_ptr[i] = (JCOEF) temp; |

474 | } |

475 | |

476 | #endif |

477 | |

478 | } |

479 | |

480 | |

481 | /* |

482 | * Perform forward DCT on one or more blocks of a component. |

483 | * |

484 | * The input samples are taken from the sample_data[] array starting at |

485 | * position start_row/start_col, and moving to the right for any additional |

486 | * blocks. The quantized coefficients are returned in coef_blocks[]. |

487 | */ |

488 | |

489 | METHODDEF(void) |

490 | forward_DCT (j_compress_ptr cinfo, jpeg_component_info *compptr, |

491 | JSAMPARRAY sample_data, JBLOCKROW coef_blocks, |

492 | JDIMENSION start_row, JDIMENSION start_col, |

493 | JDIMENSION num_blocks) |

494 | /* This version is used for integer DCT implementations. */ |

495 | { |

496 | /* This routine is heavily used, so it's worth coding it tightly. */ |

497 | my_fdct_ptr fdct = (my_fdct_ptr) cinfo->fdct; |

498 | DCTELEM *divisors = fdct->divisors[compptr->quant_tbl_no]; |

499 | DCTELEM *workspace; |

500 | JDIMENSION bi; |

501 | |

502 | /* Make sure the compiler doesn't look up these every pass */ |

503 | forward_DCT_method_ptr do_dct = fdct->dct; |

504 | convsamp_method_ptr do_convsamp = fdct->convsamp; |

505 | quantize_method_ptr do_quantize = fdct->quantize; |

506 | workspace = fdct->workspace; |

507 | |

508 | sample_data += start_row; /* fold in the vertical offset once */ |

509 | |

510 | for (bi = 0; bi < num_blocks; bi++, start_col += DCTSIZE) { |

511 | /* Load data into workspace, applying unsigned->signed conversion */ |

512 | (*do_convsamp) (sample_data, start_col, workspace); |

513 | |

514 | /* Perform the DCT */ |

515 | (*do_dct) (workspace); |

516 | |

517 | /* Quantize/descale the coefficients, and store into coef_blocks[] */ |

518 | (*do_quantize) (coef_blocks[bi], divisors, workspace); |

519 | } |

520 | } |

521 | |

522 | |

523 | #ifdef DCT_FLOAT_SUPPORTED |

524 | |

525 | |

526 | METHODDEF(void) |

527 | convsamp_float (JSAMPARRAY sample_data, JDIMENSION start_col, FAST_FLOAT *workspace) |

528 | { |

529 | register FAST_FLOAT *workspaceptr; |

530 | register JSAMPROW elemptr; |

531 | register int elemr; |

532 | |

533 | workspaceptr = workspace; |

534 | for (elemr = 0; elemr < DCTSIZE; elemr++) { |

535 | elemptr = sample_data[elemr] + start_col; |

536 | #if DCTSIZE == 8 /* unroll the inner loop */ |

537 | *workspaceptr++ = (FAST_FLOAT)(GETJSAMPLE(*elemptr++) - CENTERJSAMPLE); |

538 | *workspaceptr++ = (FAST_FLOAT)(GETJSAMPLE(*elemptr++) - CENTERJSAMPLE); |

539 | *workspaceptr++ = (FAST_FLOAT)(GETJSAMPLE(*elemptr++) - CENTERJSAMPLE); |

540 | *workspaceptr++ = (FAST_FLOAT)(GETJSAMPLE(*elemptr++) - CENTERJSAMPLE); |

541 | *workspaceptr++ = (FAST_FLOAT)(GETJSAMPLE(*elemptr++) - CENTERJSAMPLE); |

542 | *workspaceptr++ = (FAST_FLOAT)(GETJSAMPLE(*elemptr++) - CENTERJSAMPLE); |

543 | *workspaceptr++ = (FAST_FLOAT)(GETJSAMPLE(*elemptr++) - CENTERJSAMPLE); |

544 | *workspaceptr++ = (FAST_FLOAT)(GETJSAMPLE(*elemptr++) - CENTERJSAMPLE); |

545 | #else |

546 | { |

547 | register int elemc; |

548 | for (elemc = DCTSIZE; elemc > 0; elemc--) |

549 | *workspaceptr++ = (FAST_FLOAT) |

550 | (GETJSAMPLE(*elemptr++) - CENTERJSAMPLE); |

551 | } |

552 | #endif |

553 | } |

554 | } |

555 | |

556 | |

557 | METHODDEF(void) |

558 | quantize_float (JCOEFPTR coef_block, FAST_FLOAT *divisors, FAST_FLOAT *workspace) |

559 | { |

560 | register FAST_FLOAT temp; |

561 | register int i; |

562 | register JCOEFPTR output_ptr = coef_block; |

563 | |

564 | for (i = 0; i < DCTSIZE2; i++) { |

565 | /* Apply the quantization and scaling factor */ |

566 | temp = workspace[i] * divisors[i]; |

567 | |

568 | /* Round to nearest integer. |

569 | * Since C does not specify the direction of rounding for negative |

570 | * quotients, we have to force the dividend positive for portability. |

571 | * The maximum coefficient size is +-16K (for 12-bit data), so this |

572 | * code should work for either 16-bit or 32-bit ints. |

573 | */ |

574 | output_ptr[i] = (JCOEF) ((int) (temp + (FAST_FLOAT) 16384.5) - 16384); |

575 | } |

576 | } |

577 | |

578 | |

579 | METHODDEF(void) |

580 | forward_DCT_float (j_compress_ptr cinfo, jpeg_component_info *compptr, |

581 | JSAMPARRAY sample_data, JBLOCKROW coef_blocks, |

582 | JDIMENSION start_row, JDIMENSION start_col, |

583 | JDIMENSION num_blocks) |

584 | /* This version is used for floating-point DCT implementations. */ |

585 | { |

586 | /* This routine is heavily used, so it's worth coding it tightly. */ |

587 | my_fdct_ptr fdct = (my_fdct_ptr) cinfo->fdct; |

588 | FAST_FLOAT *divisors = fdct->float_divisors[compptr->quant_tbl_no]; |

589 | FAST_FLOAT *workspace; |

590 | JDIMENSION bi; |

591 | |

592 | |

593 | /* Make sure the compiler doesn't look up these every pass */ |

594 | float_DCT_method_ptr do_dct = fdct->float_dct; |

595 | float_convsamp_method_ptr do_convsamp = fdct->float_convsamp; |

596 | float_quantize_method_ptr do_quantize = fdct->float_quantize; |

597 | workspace = fdct->float_workspace; |

598 | |

599 | sample_data += start_row; /* fold in the vertical offset once */ |

600 | |

601 | for (bi = 0; bi < num_blocks; bi++, start_col += DCTSIZE) { |

602 | /* Load data into workspace, applying unsigned->signed conversion */ |

603 | (*do_convsamp) (sample_data, start_col, workspace); |

604 | |

605 | /* Perform the DCT */ |

606 | (*do_dct) (workspace); |

607 | |

608 | /* Quantize/descale the coefficients, and store into coef_blocks[] */ |

609 | (*do_quantize) (coef_blocks[bi], divisors, workspace); |

610 | } |

611 | } |

612 | |

613 | #endif /* DCT_FLOAT_SUPPORTED */ |

614 | |

615 | |

616 | /* |

617 | * Initialize FDCT manager. |

618 | */ |

619 | |

620 | GLOBAL(void) |

621 | jinit_forward_dct (j_compress_ptr cinfo) |

622 | { |

623 | my_fdct_ptr fdct; |

624 | int i; |

625 | |

626 | fdct = (my_fdct_ptr) |

627 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |

628 | sizeof(my_fdct_controller)); |

629 | cinfo->fdct = (struct jpeg_forward_dct *) fdct; |

630 | fdct->pub.start_pass = start_pass_fdctmgr; |

631 | |

632 | /* First determine the DCT... */ |

633 | switch (cinfo->dct_method) { |

634 | #ifdef DCT_ISLOW_SUPPORTED |

635 | case JDCT_ISLOW: |

636 | fdct->pub.forward_DCT = forward_DCT; |

637 | if (jsimd_can_fdct_islow()) |

638 | fdct->dct = jsimd_fdct_islow; |

639 | else |

640 | fdct->dct = jpeg_fdct_islow; |

641 | break; |

642 | #endif |

643 | #ifdef DCT_IFAST_SUPPORTED |

644 | case JDCT_IFAST: |

645 | fdct->pub.forward_DCT = forward_DCT; |

646 | if (jsimd_can_fdct_ifast()) |

647 | fdct->dct = jsimd_fdct_ifast; |

648 | else |

649 | fdct->dct = jpeg_fdct_ifast; |

650 | break; |

651 | #endif |

652 | #ifdef DCT_FLOAT_SUPPORTED |

653 | case JDCT_FLOAT: |

654 | fdct->pub.forward_DCT = forward_DCT_float; |

655 | if (jsimd_can_fdct_float()) |

656 | fdct->float_dct = jsimd_fdct_float; |

657 | else |

658 | fdct->float_dct = jpeg_fdct_float; |

659 | break; |

660 | #endif |

661 | default: |

662 | ERREXIT(cinfo, JERR_NOT_COMPILED); |

663 | break; |

664 | } |

665 | |

666 | /* ...then the supporting stages. */ |

667 | switch (cinfo->dct_method) { |

668 | #ifdef DCT_ISLOW_SUPPORTED |

669 | case JDCT_ISLOW: |

670 | #endif |

671 | #ifdef DCT_IFAST_SUPPORTED |

672 | case JDCT_IFAST: |

673 | #endif |

674 | #if defined(DCT_ISLOW_SUPPORTED) || defined(DCT_IFAST_SUPPORTED) |

675 | if (jsimd_can_convsamp()) |

676 | fdct->convsamp = jsimd_convsamp; |

677 | else |

678 | fdct->convsamp = convsamp; |

679 | if (jsimd_can_quantize()) |

680 | fdct->quantize = jsimd_quantize; |

681 | else |

682 | fdct->quantize = quantize; |

683 | break; |

684 | #endif |

685 | #ifdef DCT_FLOAT_SUPPORTED |

686 | case JDCT_FLOAT: |

687 | if (jsimd_can_convsamp_float()) |

688 | fdct->float_convsamp = jsimd_convsamp_float; |

689 | else |

690 | fdct->float_convsamp = convsamp_float; |

691 | if (jsimd_can_quantize_float()) |

692 | fdct->float_quantize = jsimd_quantize_float; |

693 | else |

694 | fdct->float_quantize = quantize_float; |

695 | break; |

696 | #endif |

697 | default: |

698 | ERREXIT(cinfo, JERR_NOT_COMPILED); |

699 | break; |

700 | } |

701 | |

702 | /* Allocate workspace memory */ |

703 | #ifdef DCT_FLOAT_SUPPORTED |

704 | if (cinfo->dct_method == JDCT_FLOAT) |

705 | fdct->float_workspace = (FAST_FLOAT *) |

706 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |

707 | sizeof(FAST_FLOAT) * DCTSIZE2); |

708 | else |

709 | #endif |

710 | fdct->workspace = (DCTELEM *) |

711 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |

712 | sizeof(DCTELEM) * DCTSIZE2); |

713 | |

714 | /* Mark divisor tables unallocated */ |

715 | for (i = 0; i < NUM_QUANT_TBLS; i++) { |

716 | fdct->divisors[i] = NULL; |

717 | #ifdef DCT_FLOAT_SUPPORTED |

718 | fdct->float_divisors[i] = NULL; |

719 | #endif |

720 | } |

721 | } |

722 |