author | phh |
Fri, 30 Jun 2017 16:42:49 +0200 | |
changeset 46874 | 13b399635568 |
parent 25859 | 3317bb8137f4 |
permissions | -rw-r--r-- |
2 | 1 |
/* |
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* reserved comment block |
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* DO NOT REMOVE OR ALTER! |
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*/ |
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/* |
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* jdphuff.c |
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* |
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* Copyright (C) 1995-1997, Thomas G. Lane. |
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* This file is part of the Independent JPEG Group's software. |
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* For conditions of distribution and use, see the accompanying README file. |
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* |
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* This file contains Huffman entropy decoding routines for progressive JPEG. |
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* |
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* Much of the complexity here has to do with supporting input suspension. |
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* If the data source module demands suspension, we want to be able to back |
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* up to the start of the current MCU. To do this, we copy state variables |
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* into local working storage, and update them back to the permanent |
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* storage only upon successful completion of an MCU. |
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*/ |
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#define JPEG_INTERNALS |
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#include "jinclude.h" |
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#include "jpeglib.h" |
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#include "jdhuff.h" /* Declarations shared with jdhuff.c */ |
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#ifdef D_PROGRESSIVE_SUPPORTED |
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/* |
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* Expanded entropy decoder object for progressive Huffman decoding. |
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* |
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* The savable_state subrecord contains fields that change within an MCU, |
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* but must not be updated permanently until we complete the MCU. |
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*/ |
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typedef struct { |
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unsigned int EOBRUN; /* remaining EOBs in EOBRUN */ |
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int last_dc_val[MAX_COMPS_IN_SCAN]; /* last DC coef for each component */ |
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} savable_state; |
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/* This macro is to work around compilers with missing or broken |
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* structure assignment. You'll need to fix this code if you have |
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* such a compiler and you change MAX_COMPS_IN_SCAN. |
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*/ |
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#ifndef NO_STRUCT_ASSIGN |
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#define ASSIGN_STATE(dest,src) ((dest) = (src)) |
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#else |
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#if MAX_COMPS_IN_SCAN == 4 |
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#define ASSIGN_STATE(dest,src) \ |
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((dest).EOBRUN = (src).EOBRUN, \ |
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(dest).last_dc_val[0] = (src).last_dc_val[0], \ |
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(dest).last_dc_val[1] = (src).last_dc_val[1], \ |
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(dest).last_dc_val[2] = (src).last_dc_val[2], \ |
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(dest).last_dc_val[3] = (src).last_dc_val[3]) |
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#endif |
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#endif |
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typedef struct { |
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struct jpeg_entropy_decoder pub; /* public fields */ |
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/* These fields are loaded into local variables at start of each MCU. |
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* In case of suspension, we exit WITHOUT updating them. |
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*/ |
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bitread_perm_state bitstate; /* Bit buffer at start of MCU */ |
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savable_state saved; /* Other state at start of MCU */ |
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/* These fields are NOT loaded into local working state. */ |
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unsigned int restarts_to_go; /* MCUs left in this restart interval */ |
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/* Pointers to derived tables (these workspaces have image lifespan) */ |
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d_derived_tbl * derived_tbls[NUM_HUFF_TBLS]; |
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d_derived_tbl * ac_derived_tbl; /* active table during an AC scan */ |
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} phuff_entropy_decoder; |
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typedef phuff_entropy_decoder * phuff_entropy_ptr; |
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/* Forward declarations */ |
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METHODDEF(boolean) decode_mcu_DC_first JPP((j_decompress_ptr cinfo, |
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JBLOCKROW *MCU_data)); |
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METHODDEF(boolean) decode_mcu_AC_first JPP((j_decompress_ptr cinfo, |
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JBLOCKROW *MCU_data)); |
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METHODDEF(boolean) decode_mcu_DC_refine JPP((j_decompress_ptr cinfo, |
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JBLOCKROW *MCU_data)); |
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METHODDEF(boolean) decode_mcu_AC_refine JPP((j_decompress_ptr cinfo, |
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JBLOCKROW *MCU_data)); |
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/* |
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* Initialize for a Huffman-compressed scan. |
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*/ |
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METHODDEF(void) |
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start_pass_phuff_decoder (j_decompress_ptr cinfo) |
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{ |
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phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; |
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boolean is_DC_band, bad; |
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int ci, coefi, tbl; |
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int *coef_bit_ptr; |
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jpeg_component_info * compptr; |
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is_DC_band = (cinfo->Ss == 0); |
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/* Validate scan parameters */ |
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bad = FALSE; |
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if (is_DC_band) { |
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if (cinfo->Se != 0) |
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bad = TRUE; |
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} else { |
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/* need not check Ss/Se < 0 since they came from unsigned bytes */ |
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if (cinfo->Ss > cinfo->Se || cinfo->Se >= DCTSIZE2) |
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bad = TRUE; |
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/* AC scans may have only one component */ |
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if (cinfo->comps_in_scan != 1) |
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bad = TRUE; |
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} |
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if (cinfo->Ah != 0) { |
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/* Successive approximation refinement scan: must have Al = Ah-1. */ |
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if (cinfo->Al != cinfo->Ah-1) |
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bad = TRUE; |
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} |
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if (cinfo->Al > 13) /* need not check for < 0 */ |
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bad = TRUE; |
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/* Arguably the maximum Al value should be less than 13 for 8-bit precision, |
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* but the spec doesn't say so, and we try to be liberal about what we |
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* accept. Note: large Al values could result in out-of-range DC |
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* coefficients during early scans, leading to bizarre displays due to |
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* overflows in the IDCT math. But we won't crash. |
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*/ |
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if (bad) |
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ERREXIT4(cinfo, JERR_BAD_PROGRESSION, |
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cinfo->Ss, cinfo->Se, cinfo->Ah, cinfo->Al); |
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/* Update progression status, and verify that scan order is legal. |
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* Note that inter-scan inconsistencies are treated as warnings |
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* not fatal errors ... not clear if this is right way to behave. |
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*/ |
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for (ci = 0; ci < cinfo->comps_in_scan; ci++) { |
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int cindex = cinfo->cur_comp_info[ci]->component_index; |
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coef_bit_ptr = & cinfo->coef_bits[cindex][0]; |
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if (!is_DC_band && coef_bit_ptr[0] < 0) /* AC without prior DC scan */ |
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WARNMS2(cinfo, JWRN_BOGUS_PROGRESSION, cindex, 0); |
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for (coefi = cinfo->Ss; coefi <= cinfo->Se; coefi++) { |
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int expected = (coef_bit_ptr[coefi] < 0) ? 0 : coef_bit_ptr[coefi]; |
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if (cinfo->Ah != expected) |
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WARNMS2(cinfo, JWRN_BOGUS_PROGRESSION, cindex, coefi); |
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coef_bit_ptr[coefi] = cinfo->Al; |
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} |
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} |
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/* Select MCU decoding routine */ |
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if (cinfo->Ah == 0) { |
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if (is_DC_band) |
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entropy->pub.decode_mcu = decode_mcu_DC_first; |
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else |
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entropy->pub.decode_mcu = decode_mcu_AC_first; |
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} else { |
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if (is_DC_band) |
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entropy->pub.decode_mcu = decode_mcu_DC_refine; |
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else |
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entropy->pub.decode_mcu = decode_mcu_AC_refine; |
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} |
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for (ci = 0; ci < cinfo->comps_in_scan; ci++) { |
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compptr = cinfo->cur_comp_info[ci]; |
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/* Make sure requested tables are present, and compute derived tables. |
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* We may build same derived table more than once, but it's not expensive. |
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*/ |
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if (is_DC_band) { |
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if (cinfo->Ah == 0) { /* DC refinement needs no table */ |
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tbl = compptr->dc_tbl_no; |
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jpeg_make_d_derived_tbl(cinfo, TRUE, tbl, |
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& entropy->derived_tbls[tbl]); |
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} |
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} else { |
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tbl = compptr->ac_tbl_no; |
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jpeg_make_d_derived_tbl(cinfo, FALSE, tbl, |
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& entropy->derived_tbls[tbl]); |
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/* remember the single active table */ |
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entropy->ac_derived_tbl = entropy->derived_tbls[tbl]; |
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} |
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/* Initialize DC predictions to 0 */ |
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entropy->saved.last_dc_val[ci] = 0; |
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} |
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/* Initialize bitread state variables */ |
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entropy->bitstate.bits_left = 0; |
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entropy->bitstate.get_buffer = 0; /* unnecessary, but keeps Purify quiet */ |
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entropy->pub.insufficient_data = FALSE; |
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/* Initialize private state variables */ |
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entropy->saved.EOBRUN = 0; |
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/* Initialize restart counter */ |
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entropy->restarts_to_go = cinfo->restart_interval; |
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} |
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/* |
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* Figure F.12: extend sign bit. |
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* On some machines, a shift and add will be faster than a table lookup. |
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*/ |
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#ifdef AVOID_TABLES |
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#define HUFF_EXTEND(x,s) ((x) < (1<<((s)-1)) ? (x) + (((-1)<<(s)) + 1) : (x)) |
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#else |
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#define HUFF_EXTEND(x,s) ((x) < extend_test[s] ? (x) + extend_offset[s] : (x)) |
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static const int extend_test[16] = /* entry n is 2**(n-1) */ |
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{ 0, 0x0001, 0x0002, 0x0004, 0x0008, 0x0010, 0x0020, 0x0040, 0x0080, |
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0x0100, 0x0200, 0x0400, 0x0800, 0x1000, 0x2000, 0x4000 }; |
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static const int extend_offset[16] = /* entry n is (-1 << n) + 1 */ |
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46874
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8182299: Enable disabled clang warnings, build on OSX 10 + Xcode 8
phh
parents:
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{ 0, |
13b399635568
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phh
parents:
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(int)(((unsigned)(~0)<<1) + 1), (int)(((unsigned)(~0)<<2) + 1), |
13b399635568
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(int)(((unsigned)(~0)<<3) + 1), (int)(((unsigned)(~0)<<4) + 1), |
13b399635568
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(int)(((unsigned)(~0)<<5) + 1), (int)(((unsigned)(~0)<<6) + 1), |
13b399635568
8182299: Enable disabled clang warnings, build on OSX 10 + Xcode 8
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parents:
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(int)(((unsigned)(~0)<<7) + 1), (int)(((unsigned)(~0)<<8) + 1), |
13b399635568
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(int)(((unsigned)(~0)<<9) + 1), (int)(((unsigned)(~0)<<10) + 1), |
13b399635568
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(int)(((unsigned)(~0)<<11) + 1), (int)(((unsigned)(~0)<<12) + 1), |
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(int)(((unsigned)(~0)<<13) + 1), (int)(((unsigned)(~0)<<14) + 1), |
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(int)(((unsigned)(~0)<<15) + 1) }; |
2 | 227 |
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#endif /* AVOID_TABLES */ |
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/* |
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* Check for a restart marker & resynchronize decoder. |
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* Returns FALSE if must suspend. |
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*/ |
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LOCAL(boolean) |
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process_restart (j_decompress_ptr cinfo) |
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{ |
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phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; |
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int ci; |
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/* Throw away any unused bits remaining in bit buffer; */ |
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/* include any full bytes in next_marker's count of discarded bytes */ |
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cinfo->marker->discarded_bytes += entropy->bitstate.bits_left / 8; |
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entropy->bitstate.bits_left = 0; |
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/* Advance past the RSTn marker */ |
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if (! (*cinfo->marker->read_restart_marker) (cinfo)) |
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return FALSE; |
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/* Re-initialize DC predictions to 0 */ |
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for (ci = 0; ci < cinfo->comps_in_scan; ci++) |
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entropy->saved.last_dc_val[ci] = 0; |
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/* Re-init EOB run count, too */ |
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entropy->saved.EOBRUN = 0; |
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/* Reset restart counter */ |
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entropy->restarts_to_go = cinfo->restart_interval; |
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/* Reset out-of-data flag, unless read_restart_marker left us smack up |
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* against a marker. In that case we will end up treating the next data |
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* segment as empty, and we can avoid producing bogus output pixels by |
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* leaving the flag set. |
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*/ |
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if (cinfo->unread_marker == 0) |
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entropy->pub.insufficient_data = FALSE; |
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return TRUE; |
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} |
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270 |
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271 |
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/* |
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* Huffman MCU decoding. |
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* Each of these routines decodes and returns one MCU's worth of |
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* Huffman-compressed coefficients. |
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* The coefficients are reordered from zigzag order into natural array order, |
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* but are not dequantized. |
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* |
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* The i'th block of the MCU is stored into the block pointed to by |
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* MCU_data[i]. WE ASSUME THIS AREA IS INITIALLY ZEROED BY THE CALLER. |
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* |
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282 |
* We return FALSE if data source requested suspension. In that case no |
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283 |
* changes have been made to permanent state. (Exception: some output |
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* coefficients may already have been assigned. This is harmless for |
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* spectral selection, since we'll just re-assign them on the next call. |
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* Successive approximation AC refinement has to be more careful, however.) |
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*/ |
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288 |
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289 |
/* |
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290 |
* MCU decoding for DC initial scan (either spectral selection, |
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291 |
* or first pass of successive approximation). |
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292 |
*/ |
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293 |
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294 |
METHODDEF(boolean) |
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decode_mcu_DC_first (j_decompress_ptr cinfo, JBLOCKROW *MCU_data) |
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{ |
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297 |
phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; |
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int Al = cinfo->Al; |
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299 |
register int s, r; |
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300 |
int blkn, ci; |
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301 |
JBLOCKROW block; |
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302 |
BITREAD_STATE_VARS; |
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303 |
savable_state state; |
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304 |
d_derived_tbl * tbl; |
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305 |
jpeg_component_info * compptr; |
|
306 |
||
307 |
/* Process restart marker if needed; may have to suspend */ |
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308 |
if (cinfo->restart_interval) { |
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309 |
if (entropy->restarts_to_go == 0) |
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310 |
if (! process_restart(cinfo)) |
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311 |
return FALSE; |
|
312 |
} |
|
313 |
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314 |
/* If we've run out of data, just leave the MCU set to zeroes. |
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315 |
* This way, we return uniform gray for the remainder of the segment. |
|
316 |
*/ |
|
317 |
if (! entropy->pub.insufficient_data) { |
|
318 |
||
319 |
/* Load up working state */ |
|
320 |
BITREAD_LOAD_STATE(cinfo,entropy->bitstate); |
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321 |
ASSIGN_STATE(state, entropy->saved); |
|
322 |
||
323 |
/* Outer loop handles each block in the MCU */ |
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324 |
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325 |
for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) { |
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326 |
block = MCU_data[blkn]; |
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327 |
ci = cinfo->MCU_membership[blkn]; |
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328 |
compptr = cinfo->cur_comp_info[ci]; |
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329 |
tbl = entropy->derived_tbls[compptr->dc_tbl_no]; |
|
330 |
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331 |
/* Decode a single block's worth of coefficients */ |
|
332 |
||
333 |
/* Section F.2.2.1: decode the DC coefficient difference */ |
|
334 |
HUFF_DECODE(s, br_state, tbl, return FALSE, label1); |
|
335 |
if (s) { |
|
336 |
CHECK_BIT_BUFFER(br_state, s, return FALSE); |
|
337 |
r = GET_BITS(s); |
|
338 |
s = HUFF_EXTEND(r, s); |
|
339 |
} |
|
340 |
||
341 |
/* Convert DC difference to actual value, update last_dc_val */ |
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342 |
s += state.last_dc_val[ci]; |
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343 |
state.last_dc_val[ci] = s; |
|
344 |
/* Scale and output the coefficient (assumes jpeg_natural_order[0]=0) */ |
|
345 |
(*block)[0] = (JCOEF) (s << Al); |
|
346 |
} |
|
347 |
||
348 |
/* Completed MCU, so update state */ |
|
349 |
BITREAD_SAVE_STATE(cinfo,entropy->bitstate); |
|
350 |
ASSIGN_STATE(entropy->saved, state); |
|
351 |
} |
|
352 |
||
353 |
/* Account for restart interval (no-op if not using restarts) */ |
|
354 |
entropy->restarts_to_go--; |
|
355 |
||
356 |
return TRUE; |
|
357 |
} |
|
358 |
||
359 |
||
360 |
/* |
|
361 |
* MCU decoding for AC initial scan (either spectral selection, |
|
362 |
* or first pass of successive approximation). |
|
363 |
*/ |
|
364 |
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365 |
METHODDEF(boolean) |
|
366 |
decode_mcu_AC_first (j_decompress_ptr cinfo, JBLOCKROW *MCU_data) |
|
367 |
{ |
|
368 |
phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; |
|
369 |
int Se = cinfo->Se; |
|
370 |
int Al = cinfo->Al; |
|
371 |
register int s, k, r; |
|
372 |
unsigned int EOBRUN; |
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373 |
JBLOCKROW block; |
|
374 |
BITREAD_STATE_VARS; |
|
375 |
d_derived_tbl * tbl; |
|
376 |
||
377 |
/* Process restart marker if needed; may have to suspend */ |
|
378 |
if (cinfo->restart_interval) { |
|
379 |
if (entropy->restarts_to_go == 0) |
|
380 |
if (! process_restart(cinfo)) |
|
381 |
return FALSE; |
|
382 |
} |
|
383 |
||
384 |
/* If we've run out of data, just leave the MCU set to zeroes. |
|
385 |
* This way, we return uniform gray for the remainder of the segment. |
|
386 |
*/ |
|
387 |
if (! entropy->pub.insufficient_data) { |
|
388 |
||
389 |
/* Load up working state. |
|
390 |
* We can avoid loading/saving bitread state if in an EOB run. |
|
391 |
*/ |
|
392 |
EOBRUN = entropy->saved.EOBRUN; /* only part of saved state we need */ |
|
393 |
||
394 |
/* There is always only one block per MCU */ |
|
395 |
||
396 |
if (EOBRUN > 0) /* if it's a band of zeroes... */ |
|
397 |
EOBRUN--; /* ...process it now (we do nothing) */ |
|
398 |
else { |
|
399 |
BITREAD_LOAD_STATE(cinfo,entropy->bitstate); |
|
400 |
block = MCU_data[0]; |
|
401 |
tbl = entropy->ac_derived_tbl; |
|
402 |
||
403 |
for (k = cinfo->Ss; k <= Se; k++) { |
|
404 |
HUFF_DECODE(s, br_state, tbl, return FALSE, label2); |
|
405 |
r = s >> 4; |
|
406 |
s &= 15; |
|
407 |
if (s) { |
|
408 |
k += r; |
|
409 |
CHECK_BIT_BUFFER(br_state, s, return FALSE); |
|
410 |
r = GET_BITS(s); |
|
411 |
s = HUFF_EXTEND(r, s); |
|
412 |
/* Scale and output coefficient in natural (dezigzagged) order */ |
|
413 |
(*block)[jpeg_natural_order[k]] = (JCOEF) (s << Al); |
|
414 |
} else { |
|
415 |
if (r == 15) { /* ZRL */ |
|
416 |
k += 15; /* skip 15 zeroes in band */ |
|
417 |
} else { /* EOBr, run length is 2^r + appended bits */ |
|
418 |
EOBRUN = 1 << r; |
|
419 |
if (r) { /* EOBr, r > 0 */ |
|
420 |
CHECK_BIT_BUFFER(br_state, r, return FALSE); |
|
421 |
r = GET_BITS(r); |
|
422 |
EOBRUN += r; |
|
423 |
} |
|
424 |
EOBRUN--; /* this band is processed at this moment */ |
|
425 |
break; /* force end-of-band */ |
|
426 |
} |
|
427 |
} |
|
428 |
} |
|
429 |
||
430 |
BITREAD_SAVE_STATE(cinfo,entropy->bitstate); |
|
431 |
} |
|
432 |
||
433 |
/* Completed MCU, so update state */ |
|
434 |
entropy->saved.EOBRUN = EOBRUN; /* only part of saved state we need */ |
|
435 |
} |
|
436 |
||
437 |
/* Account for restart interval (no-op if not using restarts) */ |
|
438 |
entropy->restarts_to_go--; |
|
439 |
||
440 |
return TRUE; |
|
441 |
} |
|
442 |
||
443 |
||
444 |
/* |
|
445 |
* MCU decoding for DC successive approximation refinement scan. |
|
446 |
* Note: we assume such scans can be multi-component, although the spec |
|
447 |
* is not very clear on the point. |
|
448 |
*/ |
|
449 |
||
450 |
METHODDEF(boolean) |
|
451 |
decode_mcu_DC_refine (j_decompress_ptr cinfo, JBLOCKROW *MCU_data) |
|
452 |
{ |
|
453 |
phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; |
|
454 |
int p1 = 1 << cinfo->Al; /* 1 in the bit position being coded */ |
|
455 |
int blkn; |
|
456 |
JBLOCKROW block; |
|
457 |
BITREAD_STATE_VARS; |
|
458 |
||
459 |
/* Process restart marker if needed; may have to suspend */ |
|
460 |
if (cinfo->restart_interval) { |
|
461 |
if (entropy->restarts_to_go == 0) |
|
462 |
if (! process_restart(cinfo)) |
|
463 |
return FALSE; |
|
464 |
} |
|
465 |
||
466 |
/* Not worth the cycles to check insufficient_data here, |
|
467 |
* since we will not change the data anyway if we read zeroes. |
|
468 |
*/ |
|
469 |
||
470 |
/* Load up working state */ |
|
471 |
BITREAD_LOAD_STATE(cinfo,entropy->bitstate); |
|
472 |
||
473 |
/* Outer loop handles each block in the MCU */ |
|
474 |
||
475 |
for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) { |
|
476 |
block = MCU_data[blkn]; |
|
477 |
||
478 |
/* Encoded data is simply the next bit of the two's-complement DC value */ |
|
479 |
CHECK_BIT_BUFFER(br_state, 1, return FALSE); |
|
480 |
if (GET_BITS(1)) |
|
481 |
(*block)[0] |= p1; |
|
482 |
/* Note: since we use |=, repeating the assignment later is safe */ |
|
483 |
} |
|
484 |
||
485 |
/* Completed MCU, so update state */ |
|
486 |
BITREAD_SAVE_STATE(cinfo,entropy->bitstate); |
|
487 |
||
488 |
/* Account for restart interval (no-op if not using restarts) */ |
|
489 |
entropy->restarts_to_go--; |
|
490 |
||
491 |
return TRUE; |
|
492 |
} |
|
493 |
||
494 |
||
495 |
/* |
|
496 |
* MCU decoding for AC successive approximation refinement scan. |
|
497 |
*/ |
|
498 |
||
499 |
METHODDEF(boolean) |
|
500 |
decode_mcu_AC_refine (j_decompress_ptr cinfo, JBLOCKROW *MCU_data) |
|
501 |
{ |
|
502 |
phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; |
|
503 |
int Se = cinfo->Se; |
|
504 |
int p1 = 1 << cinfo->Al; /* 1 in the bit position being coded */ |
|
505 |
int m1 = (-1) << cinfo->Al; /* -1 in the bit position being coded */ |
|
506 |
register int s, k, r; |
|
507 |
unsigned int EOBRUN; |
|
508 |
JBLOCKROW block; |
|
509 |
JCOEFPTR thiscoef; |
|
510 |
BITREAD_STATE_VARS; |
|
511 |
d_derived_tbl * tbl; |
|
512 |
int num_newnz; |
|
513 |
int newnz_pos[DCTSIZE2]; |
|
514 |
||
515 |
/* Process restart marker if needed; may have to suspend */ |
|
516 |
if (cinfo->restart_interval) { |
|
517 |
if (entropy->restarts_to_go == 0) |
|
518 |
if (! process_restart(cinfo)) |
|
519 |
return FALSE; |
|
520 |
} |
|
521 |
||
522 |
/* If we've run out of data, don't modify the MCU. |
|
523 |
*/ |
|
524 |
if (! entropy->pub.insufficient_data) { |
|
525 |
||
526 |
/* Load up working state */ |
|
527 |
BITREAD_LOAD_STATE(cinfo,entropy->bitstate); |
|
528 |
EOBRUN = entropy->saved.EOBRUN; /* only part of saved state we need */ |
|
529 |
||
530 |
/* There is always only one block per MCU */ |
|
531 |
block = MCU_data[0]; |
|
532 |
tbl = entropy->ac_derived_tbl; |
|
533 |
||
534 |
/* If we are forced to suspend, we must undo the assignments to any newly |
|
535 |
* nonzero coefficients in the block, because otherwise we'd get confused |
|
536 |
* next time about which coefficients were already nonzero. |
|
537 |
* But we need not undo addition of bits to already-nonzero coefficients; |
|
538 |
* instead, we can test the current bit to see if we already did it. |
|
539 |
*/ |
|
540 |
num_newnz = 0; |
|
541 |
||
542 |
/* initialize coefficient loop counter to start of band */ |
|
543 |
k = cinfo->Ss; |
|
544 |
||
545 |
if (EOBRUN == 0) { |
|
546 |
for (; k <= Se; k++) { |
|
547 |
HUFF_DECODE(s, br_state, tbl, goto undoit, label3); |
|
548 |
r = s >> 4; |
|
549 |
s &= 15; |
|
550 |
if (s) { |
|
551 |
if (s != 1) /* size of new coef should always be 1 */ |
|
552 |
WARNMS(cinfo, JWRN_HUFF_BAD_CODE); |
|
553 |
CHECK_BIT_BUFFER(br_state, 1, goto undoit); |
|
554 |
if (GET_BITS(1)) |
|
555 |
s = p1; /* newly nonzero coef is positive */ |
|
556 |
else |
|
557 |
s = m1; /* newly nonzero coef is negative */ |
|
558 |
} else { |
|
559 |
if (r != 15) { |
|
560 |
EOBRUN = 1 << r; /* EOBr, run length is 2^r + appended bits */ |
|
561 |
if (r) { |
|
562 |
CHECK_BIT_BUFFER(br_state, r, goto undoit); |
|
563 |
r = GET_BITS(r); |
|
564 |
EOBRUN += r; |
|
565 |
} |
|
566 |
break; /* rest of block is handled by EOB logic */ |
|
567 |
} |
|
568 |
/* note s = 0 for processing ZRL */ |
|
569 |
} |
|
570 |
/* Advance over already-nonzero coefs and r still-zero coefs, |
|
571 |
* appending correction bits to the nonzeroes. A correction bit is 1 |
|
572 |
* if the absolute value of the coefficient must be increased. |
|
573 |
*/ |
|
574 |
do { |
|
575 |
thiscoef = *block + jpeg_natural_order[k]; |
|
576 |
if (*thiscoef != 0) { |
|
577 |
CHECK_BIT_BUFFER(br_state, 1, goto undoit); |
|
578 |
if (GET_BITS(1)) { |
|
579 |
if ((*thiscoef & p1) == 0) { /* do nothing if already set it */ |
|
580 |
if (*thiscoef >= 0) |
|
581 |
*thiscoef += p1; |
|
582 |
else |
|
583 |
*thiscoef += m1; |
|
584 |
} |
|
585 |
} |
|
586 |
} else { |
|
587 |
if (--r < 0) |
|
588 |
break; /* reached target zero coefficient */ |
|
589 |
} |
|
590 |
k++; |
|
591 |
} while (k <= Se); |
|
592 |
if (s) { |
|
593 |
int pos = jpeg_natural_order[k]; |
|
594 |
/* Output newly nonzero coefficient */ |
|
595 |
(*block)[pos] = (JCOEF) s; |
|
596 |
/* Remember its position in case we have to suspend */ |
|
597 |
newnz_pos[num_newnz++] = pos; |
|
598 |
} |
|
599 |
} |
|
600 |
} |
|
601 |
||
602 |
if (EOBRUN > 0) { |
|
603 |
/* Scan any remaining coefficient positions after the end-of-band |
|
604 |
* (the last newly nonzero coefficient, if any). Append a correction |
|
605 |
* bit to each already-nonzero coefficient. A correction bit is 1 |
|
606 |
* if the absolute value of the coefficient must be increased. |
|
607 |
*/ |
|
608 |
for (; k <= Se; k++) { |
|
609 |
thiscoef = *block + jpeg_natural_order[k]; |
|
610 |
if (*thiscoef != 0) { |
|
611 |
CHECK_BIT_BUFFER(br_state, 1, goto undoit); |
|
612 |
if (GET_BITS(1)) { |
|
613 |
if ((*thiscoef & p1) == 0) { /* do nothing if already changed it */ |
|
614 |
if (*thiscoef >= 0) |
|
615 |
*thiscoef += p1; |
|
616 |
else |
|
617 |
*thiscoef += m1; |
|
618 |
} |
|
619 |
} |
|
620 |
} |
|
621 |
} |
|
622 |
/* Count one block completed in EOB run */ |
|
623 |
EOBRUN--; |
|
624 |
} |
|
625 |
||
626 |
/* Completed MCU, so update state */ |
|
627 |
BITREAD_SAVE_STATE(cinfo,entropy->bitstate); |
|
628 |
entropy->saved.EOBRUN = EOBRUN; /* only part of saved state we need */ |
|
629 |
} |
|
630 |
||
631 |
/* Account for restart interval (no-op if not using restarts) */ |
|
632 |
entropy->restarts_to_go--; |
|
633 |
||
634 |
return TRUE; |
|
635 |
||
636 |
undoit: |
|
637 |
/* Re-zero any output coefficients that we made newly nonzero */ |
|
638 |
while (num_newnz > 0) |
|
639 |
(*block)[newnz_pos[--num_newnz]] = 0; |
|
640 |
||
641 |
return FALSE; |
|
642 |
} |
|
643 |
||
644 |
||
645 |
/* |
|
646 |
* Module initialization routine for progressive Huffman entropy decoding. |
|
647 |
*/ |
|
648 |
||
649 |
GLOBAL(void) |
|
650 |
jinit_phuff_decoder (j_decompress_ptr cinfo) |
|
651 |
{ |
|
652 |
phuff_entropy_ptr entropy; |
|
653 |
int *coef_bit_ptr; |
|
654 |
int ci, i; |
|
655 |
||
656 |
entropy = (phuff_entropy_ptr) |
|
657 |
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
|
658 |
SIZEOF(phuff_entropy_decoder)); |
|
659 |
cinfo->entropy = (struct jpeg_entropy_decoder *) entropy; |
|
660 |
entropy->pub.start_pass = start_pass_phuff_decoder; |
|
661 |
||
662 |
/* Mark derived tables unallocated */ |
|
663 |
for (i = 0; i < NUM_HUFF_TBLS; i++) { |
|
664 |
entropy->derived_tbls[i] = NULL; |
|
665 |
} |
|
666 |
||
667 |
/* Create progression status table */ |
|
668 |
cinfo->coef_bits = (int (*)[DCTSIZE2]) |
|
669 |
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
|
670 |
cinfo->num_components*DCTSIZE2*SIZEOF(int)); |
|
671 |
coef_bit_ptr = & cinfo->coef_bits[0][0]; |
|
672 |
for (ci = 0; ci < cinfo->num_components; ci++) |
|
673 |
for (i = 0; i < DCTSIZE2; i++) |
|
674 |
*coef_bit_ptr++ = -1; |
|
675 |
} |
|
676 |
||
677 |
#endif /* D_PROGRESSIVE_SUPPORTED */ |