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Diffstat (limited to 'src/jpeg-8c/jcarith.c')
| -rw-r--r-- | src/jpeg-8c/jcarith.c | 934 |
1 files changed, 0 insertions, 934 deletions
diff --git a/src/jpeg-8c/jcarith.c b/src/jpeg-8c/jcarith.c deleted file mode 100644 index 0b7ea55d..00000000 --- a/src/jpeg-8c/jcarith.c +++ /dev/null @@ -1,934 +0,0 @@ -/* - * jcarith.c - * - * Developed 1997-2009 by Guido Vollbeding. - * This file is part of the Independent JPEG Group's software. - * For conditions of distribution and use, see the accompanying README file. - * - * This file contains portable arithmetic entropy encoding routines for JPEG - * (implementing the ISO/IEC IS 10918-1 and CCITT Recommendation ITU-T T.81). - * - * Both sequential and progressive modes are supported in this single module. - * - * Suspension is not currently supported in this module. - */ - -#define JPEG_INTERNALS -#include "jinclude.h" -#include "jpeglib.h" - - -/* Expanded entropy encoder object for arithmetic encoding. */ - -typedef struct { - struct jpeg_entropy_encoder pub; /* public fields */ - - INT32 c; /* C register, base of coding interval, layout as in sec. D.1.3 */ - INT32 a; /* A register, normalized size of coding interval */ - INT32 sc; /* counter for stacked 0xFF values which might overflow */ - INT32 zc; /* counter for pending 0x00 output values which might * - * be discarded at the end ("Pacman" termination) */ - int ct; /* bit shift counter, determines when next byte will be written */ - int buffer; /* buffer for most recent output byte != 0xFF */ - - int last_dc_val[MAX_COMPS_IN_SCAN]; /* last DC coef for each component */ - int dc_context[MAX_COMPS_IN_SCAN]; /* context index for DC conditioning */ - - unsigned int restarts_to_go; /* MCUs left in this restart interval */ - int next_restart_num; /* next restart number to write (0-7) */ - - /* Pointers to statistics areas (these workspaces have image lifespan) */ - unsigned char * dc_stats[NUM_ARITH_TBLS]; - unsigned char * ac_stats[NUM_ARITH_TBLS]; - - /* Statistics bin for coding with fixed probability 0.5 */ - unsigned char fixed_bin[4]; -} arith_entropy_encoder; - -typedef arith_entropy_encoder * arith_entropy_ptr; - -/* The following two definitions specify the allocation chunk size - * for the statistics area. - * According to sections F.1.4.4.1.3 and F.1.4.4.2, we need at least - * 49 statistics bins for DC, and 245 statistics bins for AC coding. - * - * We use a compact representation with 1 byte per statistics bin, - * thus the numbers directly represent byte sizes. - * This 1 byte per statistics bin contains the meaning of the MPS - * (more probable symbol) in the highest bit (mask 0x80), and the - * index into the probability estimation state machine table - * in the lower bits (mask 0x7F). - */ - -#define DC_STAT_BINS 64 -#define AC_STAT_BINS 256 - -/* NOTE: Uncomment the following #define if you want to use the - * given formula for calculating the AC conditioning parameter Kx - * for spectral selection progressive coding in section G.1.3.2 - * of the spec (Kx = Kmin + SRL (8 + Se - Kmin) 4). - * Although the spec and P&M authors claim that this "has proven - * to give good results for 8 bit precision samples", I'm not - * convinced yet that this is really beneficial. - * Early tests gave only very marginal compression enhancements - * (a few - around 5 or so - bytes even for very large files), - * which would turn out rather negative if we'd suppress the - * DAC (Define Arithmetic Conditioning) marker segments for - * the default parameters in the future. - * Note that currently the marker writing module emits 12-byte - * DAC segments for a full-component scan in a color image. - * This is not worth worrying about IMHO. However, since the - * spec defines the default values to be used if the tables - * are omitted (unlike Huffman tables, which are required - * anyway), one might optimize this behaviour in the future, - * and then it would be disadvantageous to use custom tables if - * they don't provide sufficient gain to exceed the DAC size. - * - * On the other hand, I'd consider it as a reasonable result - * that the conditioning has no significant influence on the - * compression performance. This means that the basic - * statistical model is already rather stable. - * - * Thus, at the moment, we use the default conditioning values - * anyway, and do not use the custom formula. - * -#define CALCULATE_SPECTRAL_CONDITIONING - */ - -/* IRIGHT_SHIFT is like RIGHT_SHIFT, but works on int rather than INT32. - * We assume that int right shift is unsigned if INT32 right shift is, - * which should be safe. - */ - -#ifdef RIGHT_SHIFT_IS_UNSIGNED -#define ISHIFT_TEMPS int ishift_temp; -#define IRIGHT_SHIFT(x,shft) \ - ((ishift_temp = (x)) < 0 ? \ - (ishift_temp >> (shft)) | ((~0) << (16-(shft))) : \ - (ishift_temp >> (shft))) -#else -#define ISHIFT_TEMPS -#define IRIGHT_SHIFT(x,shft) ((x) >> (shft)) -#endif - - -LOCAL(void) -emit_byte (int val, j_compress_ptr cinfo) -/* Write next output byte; we do not support suspension in this module. */ -{ - struct jpeg_destination_mgr * dest = cinfo->dest; - - *dest->next_output_byte++ = (JOCTET) val; - if (--dest->free_in_buffer == 0) - if (! (*dest->empty_output_buffer) (cinfo)) - ERREXIT(cinfo, JERR_CANT_SUSPEND); -} - - -/* - * Finish up at the end of an arithmetic-compressed scan. - */ - -METHODDEF(void) -finish_pass (j_compress_ptr cinfo) -{ - arith_entropy_ptr e = (arith_entropy_ptr) cinfo->entropy; - INT32 temp; - - /* Section D.1.8: Termination of encoding */ - - /* Find the e->c in the coding interval with the largest - * number of trailing zero bits */ - if ((temp = (e->a - 1 + e->c) & 0xFFFF0000L) < e->c) - e->c = temp + 0x8000L; - else - e->c = temp; - /* Send remaining bytes to output */ - e->c <<= e->ct; - if (e->c & 0xF8000000L) { - /* One final overflow has to be handled */ - if (e->buffer >= 0) { - if (e->zc) - do emit_byte(0x00, cinfo); - while (--e->zc); - emit_byte(e->buffer + 1, cinfo); - if (e->buffer + 1 == 0xFF) - emit_byte(0x00, cinfo); - } - e->zc += e->sc; /* carry-over converts stacked 0xFF bytes to 0x00 */ - e->sc = 0; - } else { - if (e->buffer == 0) - ++e->zc; - else if (e->buffer >= 0) { - if (e->zc) - do emit_byte(0x00, cinfo); - while (--e->zc); - emit_byte(e->buffer, cinfo); - } - if (e->sc) { - if (e->zc) - do emit_byte(0x00, cinfo); - while (--e->zc); - do { - emit_byte(0xFF, cinfo); - emit_byte(0x00, cinfo); - } while (--e->sc); - } - } - /* Output final bytes only if they are not 0x00 */ - if (e->c & 0x7FFF800L) { - if (e->zc) /* output final pending zero bytes */ - do emit_byte(0x00, cinfo); - while (--e->zc); - emit_byte((e->c >> 19) & 0xFF, cinfo); - if (((e->c >> 19) & 0xFF) == 0xFF) - emit_byte(0x00, cinfo); - if (e->c & 0x7F800L) { - emit_byte((e->c >> 11) & 0xFF, cinfo); - if (((e->c >> 11) & 0xFF) == 0xFF) - emit_byte(0x00, cinfo); - } - } -} - - -/* - * The core arithmetic encoding routine (common in JPEG and JBIG). - * This needs to go as fast as possible. - * Machine-dependent optimization facilities - * are not utilized in this portable implementation. - * However, this code should be fairly efficient and - * may be a good base for further optimizations anyway. - * - * Parameter 'val' to be encoded may be 0 or 1 (binary decision). - * - * Note: I've added full "Pacman" termination support to the - * byte output routines, which is equivalent to the optional - * Discard_final_zeros procedure (Figure D.15) in the spec. - * Thus, we always produce the shortest possible output - * stream compliant to the spec (no trailing zero bytes, - * except for FF stuffing). - * - * I've also introduced a new scheme for accessing - * the probability estimation state machine table, - * derived from Markus Kuhn's JBIG implementation. - */ - -LOCAL(void) -arith_encode (j_compress_ptr cinfo, unsigned char *st, int val) -{ - register arith_entropy_ptr e = (arith_entropy_ptr) cinfo->entropy; - register unsigned char nl, nm; - register INT32 qe, temp; - register int sv; - - /* Fetch values from our compact representation of Table D.2: - * Qe values and probability estimation state machine - */ - sv = *st; - qe = jpeg_aritab[sv & 0x7F]; /* => Qe_Value */ - nl = qe & 0xFF; qe >>= 8; /* Next_Index_LPS + Switch_MPS */ - nm = qe & 0xFF; qe >>= 8; /* Next_Index_MPS */ - - /* Encode & estimation procedures per sections D.1.4 & D.1.5 */ - e->a -= qe; - if (val != (sv >> 7)) { - /* Encode the less probable symbol */ - if (e->a >= qe) { - /* If the interval size (qe) for the less probable symbol (LPS) - * is larger than the interval size for the MPS, then exchange - * the two symbols for coding efficiency, otherwise code the LPS - * as usual: */ - e->c += e->a; - e->a = qe; - } - *st = (sv & 0x80) ^ nl; /* Estimate_after_LPS */ - } else { - /* Encode the more probable symbol */ - if (e->a >= 0x8000L) - return; /* A >= 0x8000 -> ready, no renormalization required */ - if (e->a < qe) { - /* If the interval size (qe) for the less probable symbol (LPS) - * is larger than the interval size for the MPS, then exchange - * the two symbols for coding efficiency: */ - e->c += e->a; - e->a = qe; - } - *st = (sv & 0x80) ^ nm; /* Estimate_after_MPS */ - } - - /* Renormalization & data output per section D.1.6 */ - do { - e->a <<= 1; - e->c <<= 1; - if (--e->ct == 0) { - /* Another byte is ready for output */ - temp = e->c >> 19; - if (temp > 0xFF) { - /* Handle overflow over all stacked 0xFF bytes */ - if (e->buffer >= 0) { - if (e->zc) - do emit_byte(0x00, cinfo); - while (--e->zc); - emit_byte(e->buffer + 1, cinfo); - if (e->buffer + 1 == 0xFF) - emit_byte(0x00, cinfo); - } - e->zc += e->sc; /* carry-over converts stacked 0xFF bytes to 0x00 */ - e->sc = 0; - /* Note: The 3 spacer bits in the C register guarantee - * that the new buffer byte can't be 0xFF here - * (see page 160 in the P&M JPEG book). */ - e->buffer = temp & 0xFF; /* new output byte, might overflow later */ - } else if (temp == 0xFF) { - ++e->sc; /* stack 0xFF byte (which might overflow later) */ - } else { - /* Output all stacked 0xFF bytes, they will not overflow any more */ - if (e->buffer == 0) - ++e->zc; - else if (e->buffer >= 0) { - if (e->zc) - do emit_byte(0x00, cinfo); - while (--e->zc); - emit_byte(e->buffer, cinfo); - } - if (e->sc) { - if (e->zc) - do emit_byte(0x00, cinfo); - while (--e->zc); - do { - emit_byte(0xFF, cinfo); - emit_byte(0x00, cinfo); - } while (--e->sc); - } - e->buffer = temp & 0xFF; /* new output byte (can still overflow) */ - } - e->c &= 0x7FFFFL; - e->ct += 8; - } - } while (e->a < 0x8000L); -} - - -/* - * Emit a restart marker & resynchronize predictions. - */ - -LOCAL(void) -emit_restart (j_compress_ptr cinfo, int restart_num) -{ - arith_entropy_ptr entropy = (arith_entropy_ptr) cinfo->entropy; - int ci; - jpeg_component_info * compptr; - - finish_pass(cinfo); - - emit_byte(0xFF, cinfo); - emit_byte(JPEG_RST0 + restart_num, cinfo); - - /* Re-initialize statistics areas */ - for (ci = 0; ci < cinfo->comps_in_scan; ci++) { - compptr = cinfo->cur_comp_info[ci]; - /* DC needs no table for refinement scan */ - if (cinfo->Ss == 0 && cinfo->Ah == 0) { - MEMZERO(entropy->dc_stats[compptr->dc_tbl_no], DC_STAT_BINS); - /* Reset DC predictions to 0 */ - entropy->last_dc_val[ci] = 0; - entropy->dc_context[ci] = 0; - } - /* AC needs no table when not present */ - if (cinfo->Se) { - MEMZERO(entropy->ac_stats[compptr->ac_tbl_no], AC_STAT_BINS); - } - } - - /* Reset arithmetic encoding variables */ - entropy->c = 0; - entropy->a = 0x10000L; - entropy->sc = 0; - entropy->zc = 0; - entropy->ct = 11; - entropy->buffer = -1; /* empty */ -} - - -/* - * MCU encoding for DC initial scan (either spectral selection, - * or first pass of successive approximation). - */ - -METHODDEF(boolean) -encode_mcu_DC_first (j_compress_ptr cinfo, JBLOCKROW *MCU_data) -{ - arith_entropy_ptr entropy = (arith_entropy_ptr) cinfo->entropy; - JBLOCKROW block; - unsigned char *st; - int blkn, ci, tbl; - int v, v2, m; - ISHIFT_TEMPS - - /* Emit restart marker if needed */ - if (cinfo->restart_interval) { - if (entropy->restarts_to_go == 0) { - emit_restart(cinfo, entropy->next_restart_num); - entropy->restarts_to_go = cinfo->restart_interval; - entropy->next_restart_num++; - entropy->next_restart_num &= 7; - } - entropy->restarts_to_go--; - } - - /* Encode the MCU data blocks */ - for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) { - block = MCU_data[blkn]; - ci = cinfo->MCU_membership[blkn]; - tbl = cinfo->cur_comp_info[ci]->dc_tbl_no; - - /* Compute the DC value after the required point transform by Al. - * This is simply an arithmetic right shift. - */ - m = IRIGHT_SHIFT((int) ((*block)[0]), cinfo->Al); - - /* Sections F.1.4.1 & F.1.4.4.1: Encoding of DC coefficients */ - - /* Table F.4: Point to statistics bin S0 for DC coefficient coding */ - st = entropy->dc_stats[tbl] + entropy->dc_context[ci]; - - /* Figure F.4: Encode_DC_DIFF */ - if ((v = m - entropy->last_dc_val[ci]) == 0) { - arith_encode(cinfo, st, 0); - entropy->dc_context[ci] = 0; /* zero diff category */ - } else { - entropy->last_dc_val[ci] = m; - arith_encode(cinfo, st, 1); - /* Figure F.6: Encoding nonzero value v */ - /* Figure F.7: Encoding the sign of v */ - if (v > 0) { - arith_encode(cinfo, st + 1, 0); /* Table F.4: SS = S0 + 1 */ - st += 2; /* Table F.4: SP = S0 + 2 */ - entropy->dc_context[ci] = 4; /* small positive diff category */ - } else { - v = -v; - arith_encode(cinfo, st + 1, 1); /* Table F.4: SS = S0 + 1 */ - st += 3; /* Table F.4: SN = S0 + 3 */ - entropy->dc_context[ci] = 8; /* small negative diff category */ - } - /* Figure F.8: Encoding the magnitude category of v */ - m = 0; - if (v -= 1) { - arith_encode(cinfo, st, 1); - m = 1; - v2 = v; - st = entropy->dc_stats[tbl] + 20; /* Table F.4: X1 = 20 */ - while (v2 >>= 1) { - arith_encode(cinfo, st, 1); - m <<= 1; - st += 1; - } - } - arith_encode(cinfo, st, 0); - /* Section F.1.4.4.1.2: Establish dc_context conditioning category */ - if (m < (int) ((1L << cinfo->arith_dc_L[tbl]) >> 1)) - entropy->dc_context[ci] = 0; /* zero diff category */ - else if (m > (int) ((1L << cinfo->arith_dc_U[tbl]) >> 1)) - entropy->dc_context[ci] += 8; /* large diff category */ - /* Figure F.9: Encoding the magnitude bit pattern of v */ - st += 14; - while (m >>= 1) - arith_encode(cinfo, st, (m & v) ? 1 : 0); - } - } - - return TRUE; -} - - -/* - * MCU encoding for AC initial scan (either spectral selection, - * or first pass of successive approximation). - */ - -METHODDEF(boolean) -encode_mcu_AC_first (j_compress_ptr cinfo, JBLOCKROW *MCU_data) -{ - arith_entropy_ptr entropy = (arith_entropy_ptr) cinfo->entropy; - JBLOCKROW block; - unsigned char *st; - int tbl, k, ke; - int v, v2, m; - const int * natural_order; - - /* Emit restart marker if needed */ - if (cinfo->restart_interval) { - if (entropy->restarts_to_go == 0) { - emit_restart(cinfo, entropy->next_restart_num); - entropy->restarts_to_go = cinfo->restart_interval; - entropy->next_restart_num++; - entropy->next_restart_num &= 7; - } - entropy->restarts_to_go--; - } - - natural_order = cinfo->natural_order; - - /* Encode the MCU data block */ - block = MCU_data[0]; - tbl = cinfo->cur_comp_info[0]->ac_tbl_no; - - /* Sections F.1.4.2 & F.1.4.4.2: Encoding of AC coefficients */ - - /* Establish EOB (end-of-block) index */ - for (ke = cinfo->Se; ke > 0; ke--) - /* We must apply the point transform by Al. For AC coefficients this - * is an integer division with rounding towards 0. To do this portably - * in C, we shift after obtaining the absolute value. - */ - if ((v = (*block)[natural_order[ke]]) >= 0) { - if (v >>= cinfo->Al) break; - } else { - v = -v; - if (v >>= cinfo->Al) break; - } - - /* Figure F.5: Encode_AC_Coefficients */ - for (k = cinfo->Ss; k <= ke; k++) { - st = entropy->ac_stats[tbl] + 3 * (k - 1); - arith_encode(cinfo, st, 0); /* EOB decision */ - for (;;) { - if ((v = (*block)[natural_order[k]]) >= 0) { - if (v >>= cinfo->Al) { - arith_encode(cinfo, st + 1, 1); - arith_encode(cinfo, entropy->fixed_bin, 0); - break; - } - } else { - v = -v; - if (v >>= cinfo->Al) { - arith_encode(cinfo, st + 1, 1); - arith_encode(cinfo, entropy->fixed_bin, 1); - break; - } - } - arith_encode(cinfo, st + 1, 0); st += 3; k++; - } - st += 2; - /* Figure F.8: Encoding the magnitude category of v */ - m = 0; - if (v -= 1) { - arith_encode(cinfo, st, 1); - m = 1; - v2 = v; - if (v2 >>= 1) { - arith_encode(cinfo, st, 1); - m <<= 1; - st = entropy->ac_stats[tbl] + - (k <= cinfo->arith_ac_K[tbl] ? 189 : 217); - while (v2 >>= 1) { - arith_encode(cinfo, st, 1); - m <<= 1; - st += 1; - } - } - } - arith_encode(cinfo, st, 0); - /* Figure F.9: Encoding the magnitude bit pattern of v */ - st += 14; - while (m >>= 1) - arith_encode(cinfo, st, (m & v) ? 1 : 0); - } - /* Encode EOB decision only if k <= cinfo->Se */ - if (k <= cinfo->Se) { - st = entropy->ac_stats[tbl] + 3 * (k - 1); - arith_encode(cinfo, st, 1); - } - - return TRUE; -} - - -/* - * MCU encoding for DC successive approximation refinement scan. - */ - -METHODDEF(boolean) -encode_mcu_DC_refine (j_compress_ptr cinfo, JBLOCKROW *MCU_data) -{ - arith_entropy_ptr entropy = (arith_entropy_ptr) cinfo->entropy; - unsigned char *st; - int Al, blkn; - - /* Emit restart marker if needed */ - if (cinfo->restart_interval) { - if (entropy->restarts_to_go == 0) { - emit_restart(cinfo, entropy->next_restart_num); - entropy->restarts_to_go = cinfo->restart_interval; - entropy->next_restart_num++; - entropy->next_restart_num &= 7; - } - entropy->restarts_to_go--; - } - - st = entropy->fixed_bin; /* use fixed probability estimation */ - Al = cinfo->Al; - - /* Encode the MCU data blocks */ - for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) { - /* We simply emit the Al'th bit of the DC coefficient value. */ - arith_encode(cinfo, st, (MCU_data[blkn][0][0] >> Al) & 1); - } - - return TRUE; -} - - -/* - * MCU encoding for AC successive approximation refinement scan. - */ - -METHODDEF(boolean) -encode_mcu_AC_refine (j_compress_ptr cinfo, JBLOCKROW *MCU_data) -{ - arith_entropy_ptr entropy = (arith_entropy_ptr) cinfo->entropy; - JBLOCKROW block; - unsigned char *st; - int tbl, k, ke, kex; - int v; - const int * natural_order; - - /* Emit restart marker if needed */ - if (cinfo->restart_interval) { - if (entropy->restarts_to_go == 0) { - emit_restart(cinfo, entropy->next_restart_num); - entropy->restarts_to_go = cinfo->restart_interval; - entropy->next_restart_num++; - entropy->next_restart_num &= 7; - } - entropy->restarts_to_go--; - } - - natural_order = cinfo->natural_order; - - /* Encode the MCU data block */ - block = MCU_data[0]; - tbl = cinfo->cur_comp_info[0]->ac_tbl_no; - - /* Section G.1.3.3: Encoding of AC coefficients */ - - /* Establish EOB (end-of-block) index */ - for (ke = cinfo->Se; ke > 0; ke--) - /* We must apply the point transform by Al. For AC coefficients this - * is an integer division with rounding towards 0. To do this portably - * in C, we shift after obtaining the absolute value. - */ - if ((v = (*block)[natural_order[ke]]) >= 0) { - if (v >>= cinfo->Al) break; - } else { - v = -v; - if (v >>= cinfo->Al) break; - } - - /* Establish EOBx (previous stage end-of-block) index */ - for (kex = ke; kex > 0; kex--) - if ((v = (*block)[natural_order[kex]]) >= 0) { - if (v >>= cinfo->Ah) break; - } else { - v = -v; - if (v >>= cinfo->Ah) break; - } - - /* Figure G.10: Encode_AC_Coefficients_SA */ - for (k = cinfo->Ss; k <= ke; k++) { - st = entropy->ac_stats[tbl] + 3 * (k - 1); - if (k > kex) - arith_encode(cinfo, st, 0); /* EOB decision */ - for (;;) { - if ((v = (*block)[natural_order[k]]) >= 0) { - if (v >>= cinfo->Al) { - if (v >> 1) /* previously nonzero coef */ - arith_encode(cinfo, st + 2, (v & 1)); - else { /* newly nonzero coef */ - arith_encode(cinfo, st + 1, 1); - arith_encode(cinfo, entropy->fixed_bin, 0); - } - break; - } - } else { - v = -v; - if (v >>= cinfo->Al) { - if (v >> 1) /* previously nonzero coef */ - arith_encode(cinfo, st + 2, (v & 1)); - else { /* newly nonzero coef */ - arith_encode(cinfo, st + 1, 1); - arith_encode(cinfo, entropy->fixed_bin, 1); - } - break; - } - } - arith_encode(cinfo, st + 1, 0); st += 3; k++; - } - } - /* Encode EOB decision only if k <= cinfo->Se */ - if (k <= cinfo->Se) { - st = entropy->ac_stats[tbl] + 3 * (k - 1); - arith_encode(cinfo, st, 1); - } - - return TRUE; -} - - -/* - * Encode and output one MCU's worth of arithmetic-compressed coefficients. - */ - -METHODDEF(boolean) -encode_mcu (j_compress_ptr cinfo, JBLOCKROW *MCU_data) -{ - arith_entropy_ptr entropy = (arith_entropy_ptr) cinfo->entropy; - jpeg_component_info * compptr; - JBLOCKROW block; - unsigned char *st; - int blkn, ci, tbl, k, ke; - int v, v2, m; - const int * natural_order; - - /* Emit restart marker if needed */ - if (cinfo->restart_interval) { - if (entropy->restarts_to_go == 0) { - emit_restart(cinfo, entropy->next_restart_num); - entropy->restarts_to_go = cinfo->restart_interval; - entropy->next_restart_num++; - entropy->next_restart_num &= 7; - } - entropy->restarts_to_go--; - } - - natural_order = cinfo->natural_order; - - /* Encode the MCU data blocks */ - for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) { - block = MCU_data[blkn]; - ci = cinfo->MCU_membership[blkn]; - compptr = cinfo->cur_comp_info[ci]; - - /* Sections F.1.4.1 & F.1.4.4.1: Encoding of DC coefficients */ - - tbl = compptr->dc_tbl_no; - - /* Table F.4: Point to statistics bin S0 for DC coefficient coding */ - st = entropy->dc_stats[tbl] + entropy->dc_context[ci]; - - /* Figure F.4: Encode_DC_DIFF */ - if ((v = (*block)[0] - entropy->last_dc_val[ci]) == 0) { - arith_encode(cinfo, st, 0); - entropy->dc_context[ci] = 0; /* zero diff category */ - } else { - entropy->last_dc_val[ci] = (*block)[0]; - arith_encode(cinfo, st, 1); - /* Figure F.6: Encoding nonzero value v */ - /* Figure F.7: Encoding the sign of v */ - if (v > 0) { - arith_encode(cinfo, st + 1, 0); /* Table F.4: SS = S0 + 1 */ - st += 2; /* Table F.4: SP = S0 + 2 */ - entropy->dc_context[ci] = 4; /* small positive diff category */ - } else { - v = -v; - arith_encode(cinfo, st + 1, 1); /* Table F.4: SS = S0 + 1 */ - st += 3; /* Table F.4: SN = S0 + 3 */ - entropy->dc_context[ci] = 8; /* small negative diff category */ - } - /* Figure F.8: Encoding the magnitude category of v */ - m = 0; - if (v -= 1) { - arith_encode(cinfo, st, 1); - m = 1; - v2 = v; - st = entropy->dc_stats[tbl] + 20; /* Table F.4: X1 = 20 */ - while (v2 >>= 1) { - arith_encode(cinfo, st, 1); - m <<= 1; - st += 1; - } - } - arith_encode(cinfo, st, 0); - /* Section F.1.4.4.1.2: Establish dc_context conditioning category */ - if (m < (int) ((1L << cinfo->arith_dc_L[tbl]) >> 1)) - entropy->dc_context[ci] = 0; /* zero diff category */ - else if (m > (int) ((1L << cinfo->arith_dc_U[tbl]) >> 1)) - entropy->dc_context[ci] += 8; /* large diff category */ - /* Figure F.9: Encoding the magnitude bit pattern of v */ - st += 14; - while (m >>= 1) - arith_encode(cinfo, st, (m & v) ? 1 : 0); - } - - /* Sections F.1.4.2 & F.1.4.4.2: Encoding of AC coefficients */ - - tbl = compptr->ac_tbl_no; - - /* Establish EOB (end-of-block) index */ - for (ke = cinfo->lim_Se; ke > 0; ke--) - if ((*block)[natural_order[ke]]) break; - - /* Figure F.5: Encode_AC_Coefficients */ - for (k = 1; k <= ke; k++) { - st = entropy->ac_stats[tbl] + 3 * (k - 1); - arith_encode(cinfo, st, 0); /* EOB decision */ - while ((v = (*block)[natural_order[k]]) == 0) { - arith_encode(cinfo, st + 1, 0); st += 3; k++; - } - arith_encode(cinfo, st + 1, 1); - /* Figure F.6: Encoding nonzero value v */ - /* Figure F.7: Encoding the sign of v */ - if (v > 0) { - arith_encode(cinfo, entropy->fixed_bin, 0); - } else { - v = -v; - arith_encode(cinfo, entropy->fixed_bin, 1); - } - st += 2; - /* Figure F.8: Encoding the magnitude category of v */ - m = 0; - if (v -= 1) { - arith_encode(cinfo, st, 1); - m = 1; - v2 = v; - if (v2 >>= 1) { - arith_encode(cinfo, st, 1); - m <<= 1; - st = entropy->ac_stats[tbl] + - (k <= cinfo->arith_ac_K[tbl] ? 189 : 217); - while (v2 >>= 1) { - arith_encode(cinfo, st, 1); - m <<= 1; - st += 1; - } - } - } - arith_encode(cinfo, st, 0); - /* Figure F.9: Encoding the magnitude bit pattern of v */ - st += 14; - while (m >>= 1) - arith_encode(cinfo, st, (m & v) ? 1 : 0); - } - /* Encode EOB decision only if k <= cinfo->lim_Se */ - if (k <= cinfo->lim_Se) { - st = entropy->ac_stats[tbl] + 3 * (k - 1); - arith_encode(cinfo, st, 1); - } - } - - return TRUE; -} - - -/* - * Initialize for an arithmetic-compressed scan. - */ - -METHODDEF(void) -start_pass (j_compress_ptr cinfo, boolean gather_statistics) -{ - arith_entropy_ptr entropy = (arith_entropy_ptr) cinfo->entropy; - int ci, tbl; - jpeg_component_info * compptr; - - if (gather_statistics) - /* Make sure to avoid that in the master control logic! - * We are fully adaptive here and need no extra - * statistics gathering pass! - */ - ERREXIT(cinfo, JERR_NOT_COMPILED); - - /* We assume jcmaster.c already validated the progressive scan parameters. */ - - /* Select execution routines */ - if (cinfo->progressive_mode) { - if (cinfo->Ah == 0) { - if (cinfo->Ss == 0) - entropy->pub.encode_mcu = encode_mcu_DC_first; - else - entropy->pub.encode_mcu = encode_mcu_AC_first; - } else { - if (cinfo->Ss == 0) - entropy->pub.encode_mcu = encode_mcu_DC_refine; - else - entropy->pub.encode_mcu = encode_mcu_AC_refine; - } - } else - entropy->pub.encode_mcu = encode_mcu; - - /* Allocate & initialize requested statistics areas */ - for (ci = 0; ci < cinfo->comps_in_scan; ci++) { - compptr = cinfo->cur_comp_info[ci]; - /* DC needs no table for refinement scan */ - if (cinfo->Ss == 0 && cinfo->Ah == 0) { - tbl = compptr->dc_tbl_no; - if (tbl < 0 || tbl >= NUM_ARITH_TBLS) - ERREXIT1(cinfo, JERR_NO_ARITH_TABLE, tbl); - if (entropy->dc_stats[tbl] == NULL) - entropy->dc_stats[tbl] = (unsigned char *) (*cinfo->mem->alloc_small) - ((j_common_ptr) cinfo, JPOOL_IMAGE, DC_STAT_BINS); - MEMZERO(entropy->dc_stats[tbl], DC_STAT_BINS); - /* Initialize DC predictions to 0 */ - entropy->last_dc_val[ci] = 0; - entropy->dc_context[ci] = 0; - } - /* AC needs no table when not present */ - if (cinfo->Se) { - tbl = compptr->ac_tbl_no; - if (tbl < 0 || tbl >= NUM_ARITH_TBLS) - ERREXIT1(cinfo, JERR_NO_ARITH_TABLE, tbl); - if (entropy->ac_stats[tbl] == NULL) - entropy->ac_stats[tbl] = (unsigned char *) (*cinfo->mem->alloc_small) - ((j_common_ptr) cinfo, JPOOL_IMAGE, AC_STAT_BINS); - MEMZERO(entropy->ac_stats[tbl], AC_STAT_BINS); -#ifdef CALCULATE_SPECTRAL_CONDITIONING - if (cinfo->progressive_mode) - /* Section G.1.3.2: Set appropriate arithmetic conditioning value Kx */ - cinfo->arith_ac_K[tbl] = cinfo->Ss + ((8 + cinfo->Se - cinfo->Ss) >> 4); -#endif - } - } - - /* Initialize arithmetic encoding variables */ - entropy->c = 0; - entropy->a = 0x10000L; - entropy->sc = 0; - entropy->zc = 0; - entropy->ct = 11; - entropy->buffer = -1; /* empty */ - - /* Initialize restart stuff */ - entropy->restarts_to_go = cinfo->restart_interval; - entropy->next_restart_num = 0; -} - - -/* - * Module initialization routine for arithmetic entropy encoding. - */ - -GLOBAL(void) -jinit_arith_encoder (j_compress_ptr cinfo) -{ - arith_entropy_ptr entropy; - int i; - - entropy = (arith_entropy_ptr) - (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, - SIZEOF(arith_entropy_encoder)); - cinfo->entropy = (struct jpeg_entropy_encoder *) entropy; - entropy->pub.start_pass = start_pass; - entropy->pub.finish_pass = finish_pass; - - /* Mark tables unallocated */ - for (i = 0; i < NUM_ARITH_TBLS; i++) { - entropy->dc_stats[i] = NULL; - entropy->ac_stats[i] = NULL; - } - - /* Initialize index for fixed probability estimation */ - entropy->fixed_bin[0] = 113; -} |