jdphuff.c

MCB2300_ucgui_LCD320240.rar LPC2368的uc/gui的移植

/*
 * jdphuff.c
 *
 * Copyright (C) 1995-1997, Thomas G. Lane.
 * 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 Huffman entropy decoding routines for progressive JPEG.
 *
 * Much of the complexity here has to do with supporting input suspension.
 * If the data source module demands suspension, we want to be able to back
 * up to the start of the current MCU.  To do this, we copy state variables
 * into local working storage, and update them back to the permanent
 * storage only upon successful completion of an MCU.
 */

#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"
#include "jdhuff.h"		/* Declarations shared with jdhuff.c */


#ifdef D_PROGRESSIVE_SUPPORTED

/*
 * Expanded entropy decoder object for progressive Huffman decoding.
 *
 * The savable_state subrecord contains fields that change within an MCU,
 * but must not be updated permanently until we complete the MCU.
 */

typedef struct
{
	unsigned int	EOBRUN;			/* remaining EOBs in EOBRUN */
	int				last_dc_val[MAX_COMPS_IN_SCAN];	/* last DC coef for each component */
} savable_state;

/* This macro is to work around compilers with missing or broken
 * structure assignment.  You'll need to fix this code if you have
 * such a compiler and you change MAX_COMPS_IN_SCAN.
 */

#ifndef NO_STRUCT_ASSIGN
#define ASSIGN_STATE(dest,src)  ((dest) = (src))
#else
#if MAX_COMPS_IN_SCAN == 4
#define ASSIGN_STATE(dest,src)  \
	((dest).EOBRUN = (src).EOBRUN, \
	 (dest).last_dc_val[0] = (src).last_dc_val[0], \
	 (dest).last_dc_val[1] = (src).last_dc_val[1], \
	 (dest).last_dc_val[2] = (src).last_dc_val[2], \
	 (dest).last_dc_val[3] = (src).last_dc_val[3])
#endif
#endif


typedef struct
{
	struct jpeg_entropy_decoder	pub; /* public fields */

	/* These fields are loaded into local variables at start of each MCU.
	 * In case of suspension, we exit WITHOUT updating them.
	 */
	bitread_perm_state			bitstate;	/* Bit buffer at start of MCU */
	savable_state				saved;		/* Other state at start of MCU */

	/* These fields are NOT loaded into local working state. */
	unsigned int				restarts_to_go;	/* MCUs left in this restart interval */

	/* Pointers to derived tables (these workspaces have image lifespan) */
	d_derived_tbl				*derived_tbls[NUM_HUFF_TBLS];

	d_derived_tbl				*ac_derived_tbl; /* active table during an AC scan */
} phuff_entropy_decoder;

typedef phuff_entropy_decoder * phuff_entropy_ptr;

/* Forward declarations */
METHODDEF(boolean) decode_mcu_DC_first JPP((j_decompress_ptr cinfo,
JBLOCKROW *MCU_data));
METHODDEF(boolean) decode_mcu_AC_first JPP((j_decompress_ptr cinfo,
JBLOCKROW *MCU_data));
METHODDEF(boolean) decode_mcu_DC_refine JPP((j_decompress_ptr cinfo,
JBLOCKROW *MCU_data));
METHODDEF(boolean) decode_mcu_AC_refine JPP((j_decompress_ptr cinfo,
JBLOCKROW *MCU_data));


/*
 * Initialize for a Huffman-compressed scan.
 */

METHODDEF(void)
start_pass_phuff_decoder(j_decompress_ptr cinfo)
{
	phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
	boolean is_DC_band, bad;
	int ci, coefi, tbl;
	int *coef_bit_ptr;
	jpeg_component_info * compptr;

	is_DC_band = (cinfo->Ss == 0);

	/* Validate scan parameters */
	bad = FALSE;
	if (is_DC_band)
	{
		if (cinfo->Se != 0)
		{
			bad = TRUE;
		}
	}
	else
	{
		/* need not check Ss/Se < 0 since they came from unsigned bytes */
		if (cinfo->Ss > cinfo->Se || cinfo->Se >= DCTSIZE2)
		{
			bad = TRUE;
		}
		/* AC scans may have only one component */
		if (cinfo->comps_in_scan != 1)
		{
			bad = TRUE;
		}
	}
	if (cinfo->Ah != 0)
	{
		/* Successive approximation refinement scan: must have Al = Ah-1. */
		if (cinfo->Al != cinfo->Ah - 1)
		{
			bad = TRUE;
		}
	}
	if (cinfo->Al > 13)		/* need not check for < 0 */
	{
		bad = TRUE;
	}
	/* Arguably the maximum Al value should be less than 13 for 8-bit precision,
	 * but the spec doesn't say so, and we try to be liberal about what we
	 * accept.  Note: large Al values could result in out-of-range DC
	 * coefficients during early scans, leading to bizarre displays due to
	 * overflows in the IDCT math.  But we won't crash.
	 */
	if (bad)
	{
		ERREXIT4(cinfo, JERR_BAD_PROGRESSION, cinfo->Ss, cinfo->Se, cinfo->Ah, cinfo->Al);
	}
	/* Update progression status, and verify that scan order is legal.
	 * Note that inter-scan inconsistencies are treated as warnings
	 * not fatal errors ... not clear if this is right way to behave.
	 */
	for (ci = 0; ci < cinfo->comps_in_scan; ci++)
	{
		int cindex = cinfo->cur_comp_info[ci]->component_index;
		coef_bit_ptr = &cinfo->coef_bits[cindex][0];
		if (!is_DC_band && coef_bit_ptr[0] < 0) /* AC without prior DC scan */
		{
			WARNMS2(cinfo, JWRN_BOGUS_PROGRESSION, cindex, 0);
		}
		for (coefi = cinfo->Ss; coefi <= cinfo->Se; coefi++)
		{
			int expected = (coef_bit_ptr[coefi] < 0) ? 0 : coef_bit_ptr[coefi];
			if (cinfo->Ah != expected)
			{
				WARNMS2(cinfo, JWRN_BOGUS_PROGRESSION, cindex, coefi);
			}
			coef_bit_ptr[coefi] = cinfo->Al;
		}
	}

	/* Select MCU decoding routine */
	if (cinfo->Ah == 0)
	{
		if (is_DC_band)
		{
			entropy->pub.decode_mcu = decode_mcu_DC_first;
		}
		else
		{
			entropy->pub.decode_mcu = decode_mcu_AC_first;
		}
	}
	else
	{
		if (is_DC_band)
		{
			entropy->pub.decode_mcu = decode_mcu_DC_refine;
		}
		else
		{
			entropy->pub.decode_mcu = decode_mcu_AC_refine;
		}
	}

	for (ci = 0; ci < cinfo->comps_in_scan; ci++)
	{
		compptr = cinfo->cur_comp_info[ci];
		/* Make sure requested tables are present, and compute derived tables.
		 * We may build same derived table more than once, but it's not expensive.
		 */
		if (is_DC_band)
		{
			if (cinfo->Ah == 0)
			{
				/* DC refinement needs no table */
				tbl = compptr->dc_tbl_no;
				jpeg_make_d_derived_tbl(cinfo, TRUE, tbl, &entropy->derived_tbls[tbl]);
			}
		}
		else
		{
			tbl = compptr->ac_tbl_no;
			jpeg_make_d_derived_tbl(cinfo, FALSE, tbl, &entropy->derived_tbls[tbl]);
			/* remember the single active table */
			entropy->ac_derived_tbl = entropy->derived_tbls[tbl];
		}
		/* Initialize DC predictions to 0 */
		entropy->saved.last_dc_val[ci] = 0;
	}

	/* Initialize bitread state variables */
	entropy->bitstate.bits_left = 0;
	entropy->bitstate.get_buffer = 0; /* unnecessary, but keeps Purify quiet */
	entropy->pub.insufficient_data = FALSE;

	/* Initialize private state variables */
	entropy->saved.EOBRUN = 0;

	/* Initialize restart counter */
	entropy->restarts_to_go = cinfo->restart_interval;
}


/*
 * Figure F.12: extend sign bit.
 * On some machines, a shift and add will be faster than a table lookup.
 */

#ifdef AVOID_TABLES

#define HUFF_EXTEND(x,s)  ((x) < (1<<((s)-1)) ? (x) + (((-1)<<(s)) + 1) : (x))

#else

#define HUFF_EXTEND(x,s)  ((x) < extend_test[s] ? (x) + extend_offset[s] : (x))

static const int extend_test[16] =   /* entry n is 2**(n-1) */
{ 0, 0x0001, 0x0002, 0x0004, 0x0008, 0x0010, 0x0020, 0x0040, 0x0080,
0x0100, 0x0200, 0x0400, 0x0800, 0x1000, 0x2000, 0x4000 };

static const int extend_offset[16] = /* entry n is (-1 << n) + 1 */
{ 0, ((-1) << 1) + 1, ((-1) << 2) + 1, ((-1) << 3) + 1, ((-1) << 4) + 1,
((-1) << 5) + 1, ((-1) << 6) + 1, ((-1) << 7) + 1, ((-1) << 8) + 1,
((-1) << 9) + 1, ((-1) << 10) + 1, ((-1) << 11) + 1, ((-1) << 12) + 1,
((-1) << 13) + 1, ((-1) << 14) + 1, ((-1) << 15) + 1 };

#endif /* AVOID_TABLES */


/*
 * Check for a restart marker & resynchronize decoder.
 * Returns FALSE if must suspend.
 */

LOCAL(boolean)
process_restart(j_decompress_ptr cinfo)
{
	phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
	int ci;

	/* Throw away any unused bits remaining in bit buffer; */
	/* include any full bytes in next_marker's count of discarded bytes */
	cinfo->marker->discarded_bytes += entropy->bitstate.bits_left / 8;
	entropy->bitstate.bits_left = 0;

	/* Advance past the RSTn marker */
	if (!(*cinfo->marker->read_restart_marker) (cinfo))
	{
		return FALSE;
	}

	/* Re-initialize DC predictions to 0 */
	for (ci = 0; ci < cinfo->comps_in_scan; ci++)
	{
		entropy->saved.last_dc_val[ci] = 0;
	}
	/* Re-init EOB run count, too */
	entropy->saved.EOBRUN = 0;

	/* Reset restart counter */
	entropy->restarts_to_go = cinfo->restart_interval;

	/* Reset out-of-data flag, unless read_restart_marker left us smack up
	 * against a marker.  In that case we will end up treating the next data
	 * segment as empty, and we can avoid producing bogus output pixels by
	 * leaving the flag set.
	 */
	if (cinfo->unread_marker == 0)
	{
		entropy->pub.insufficient_data = FALSE;
	}

	return TRUE;
}


/*
 * Huffman MCU decoding.
 * Each of these routines decodes and returns one MCU's worth of
 * Huffman-compressed coefficients. 
 * The coefficients are reordered from zigzag order into natural array order,
 * but are not dequantized.
 *
 * The i'th block of the MCU is stored into the block pointed to by
 * MCU_data[i].  WE ASSUME THIS AREA IS INITIALLY ZEROED BY THE CALLER.
 *
 * We return FALSE if data source requested suspension.  In that case no
 * changes have been made to permanent state.  (Exception: some output
 * coefficients may already have been assigned.  This is harmless for
 * spectral selection, since we'll just re-assign them on the next call.
 * Successive approximation AC refinement has to be more careful, however.)
 */

/*
 * MCU decoding for DC initial scan (either spectral selection,
 * or first pass of successive approximation).
 */

METHODDEF(boolean)
decode_mcu_DC_first(j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
{
	phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
	int Al = cinfo->Al;
	register int s, r;
	int blkn, ci;
	JBLOCKROW block;
	BITREAD_STATE_VARS;
	savable_state state;
	d_derived_tbl * tbl;
	jpeg_component_info * compptr;

	/* Process restart marker if needed; may have to suspend */
	if (cinfo->restart_interval)
	{
		if (entropy->restarts_to_go == 0)
		{
			if (!process_restart(cinfo))
			{
				return FALSE;
			}
		}
	}

	/* If we've run out of data, just leave the MCU set to zeroes.
	 * This way, we return uniform gray for the remainder of the segment.
	 */
	if (!entropy->pub.insufficient_data)
	{
		/* Load up working state */
		BITREAD_LOAD_STATE(cinfo, entropy->bitstate);
		ASSIGN_STATE(state, entropy->saved);

		/* Outer loop handles each block in the MCU */

		for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++)
		{
			block = MCU_data[blkn];
			ci = cinfo->MCU_membership[blkn];
			compptr = cinfo->cur_comp_info[ci];
			tbl = entropy->derived_tbls[compptr->dc_tbl_no];

			/* Decode a single block's worth of coefficients */

			/* Section F.2.2.1: decode the DC coefficient difference */
			HUFF_DECODE(s, br_state, tbl, return FALSE, label1);
			if (s)
			{
				CHECK_BIT_BUFFER(br_state, s, return FALSE);
				r = GET_BITS(s);
				s = HUFF_EXTEND(r, s);
			}

			/* Convert DC difference to actual value, update last_dc_val */
			s += state.last_dc_val[ci];
			state.last_dc_val[ci] = s;
			/* Scale and output the coefficient (assumes jpeg_natural_order[0]=0) */
			(*block)[0] = (JCOEF) (s << Al);
		}

		/* Completed MCU, so update state */
		BITREAD_SAVE_STATE(cinfo, entropy->bitstate);
		ASSIGN_STATE(entropy->saved, state);
	}

	/* Account for restart interval (no-op if not using restarts) */
	entropy->restarts_to_go--;