/*
 * jcphuff.c
 *
 * This file was part of the Independent JPEG Group's software:
 * Copyright (C) 1995-1997, Thomas G. Lane.
 * libjpeg-turbo Modifications:
 * Copyright (C) 2015, D. R. Commander.
 * For conditions of distribution and use, see the accompanying README.ijg
 * file.
 *
 * This file contains Huffman entropy encoding routines for progressive JPEG.
 *
 * We do not support output suspension in this module, since the library
 * currently does not allow multiple-scan files to be written with output
 * suspension.
 */

#define JPEG_INTERNALS

#include "jinclude.h"
#include "jpeglib.h"
#include "jchuff.h"             /* Declarations shared with jchuff.c */

#ifdef C_PROGRESSIVE_SUPPORTED

/* Expanded entropy encoder object for progressive Huffman encoding. */

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

	/* Mode flag: TRUE for optimization, FALSE for actual data output */
	boolean gather_statistics;

	/* Bit-level coding status.
	 * next_output_byte/free_in_buffer are local copies of cinfo->dest fields.
	 */
	JOCTET *next_output_byte;     /* => next byte to write in buffer */
	size_t free_in_buffer;        /* # of byte spaces remaining in buffer */
	size_t put_buffer;            /* current bit-accumulation buffer */
	int put_bits;                 /* # of bits now in it */
	j_compress_ptr cinfo;         /* link to cinfo (needed for dump_buffer) */

	/* Coding status for DC components */
	int last_dc_val[MAX_COMPS_IN_SCAN]; /* last DC coef for each component */

	/* Coding status for AC components */
	int ac_tbl_no;                /* the table number of the single component */
	unsigned int EOBRUN;          /* run length of EOBs */
	unsigned int BE;              /* # of buffered correction bits before MCU */
	char *bit_buffer;             /* buffer for correction bits (1 per char) */
	/* packing correction bits tightly would save some space but cost time... */

	unsigned int restarts_to_go;  /* MCUs left in this restart interval */
	int next_restart_num;         /* next restart number to write (0-7) */

	/* Pointers to derived tables (these workspaces have image lifespan).
	 * Since any one scan codes only DC or only AC, we only need one set
	 * of tables, not one for DC and one for AC.
	 */
	c_derived_tbl *derived_tbls[NUM_HUFF_TBLS];

	/* Statistics tables for optimization; again, one set is enough */
	long *count_ptrs[NUM_HUFF_TBLS];
} phuff_entropy_encoder;

typedef phuff_entropy_encoder *phuff_entropy_ptr;

/* MAX_CORR_BITS is the number of bits the AC refinement correction-bit
 * buffer can hold.  Larger sizes may slightly improve compression, but
 * 1000 is already well into the realm of overkill.
 * The minimum safe size is 64 bits.
 */

#define MAX_CORR_BITS  1000     /* Max # of correction bits I can buffer */

/* IRIGHT_SHIFT is like RIGHT_SHIFT, but works on int rather than JLONG.
 * We assume that int right shift is unsigned if JLONG 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

/* Forward declarations */
METHODDEF(boolean) encode_mcu_DC_first(j_compress_ptr cinfo,
                                       JBLOCKROW *MCU_data);

METHODDEF(boolean) encode_mcu_AC_first(j_compress_ptr cinfo,
                                       JBLOCKROW *MCU_data);

METHODDEF(boolean) encode_mcu_DC_refine(j_compress_ptr cinfo,
                                        JBLOCKROW *MCU_data);

METHODDEF(boolean) encode_mcu_AC_refine(j_compress_ptr cinfo,
                                        JBLOCKROW *MCU_data);

METHODDEF(void) finish_pass_phuff(j_compress_ptr cinfo);

METHODDEF(void) finish_pass_gather_phuff(j_compress_ptr cinfo);


/*
 * Initialize for a Huffman-compressed scan using progressive JPEG.
 */

METHODDEF(void)
start_pass_phuff(j_compress_ptr cinfo, boolean gather_statistics) {
	phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
	boolean is_DC_band;
	int ci, tbl;
	jpeg_component_info *compptr;

	entropy->cinfo = cinfo;
	entropy->gather_statistics = gather_statistics;

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

	/* We assume jcmaster.c already validated the scan parameters. */

	/* Select execution routines */
	if (cinfo->Ah == 0) {
		if (is_DC_band)
			entropy->pub.encode_mcu = encode_mcu_DC_first;
		else
			entropy->pub.encode_mcu = encode_mcu_AC_first;
	} else {
		if (is_DC_band)
			entropy->pub.encode_mcu = encode_mcu_DC_refine;
		else {
			entropy->pub.encode_mcu = encode_mcu_AC_refine;
			/* AC refinement needs a correction bit buffer */
			if (entropy->bit_buffer == NULL)
				entropy->bit_buffer = (char *)
						(*cinfo->mem->alloc_small)((j_common_ptr) cinfo, JPOOL_IMAGE,
						                           MAX_CORR_BITS * sizeof(char));
		}
	}
	if (gather_statistics)
		entropy->pub.finish_pass = finish_pass_gather_phuff;
	else
		entropy->pub.finish_pass = finish_pass_phuff;

	/* Only DC coefficients may be interleaved, so cinfo->comps_in_scan = 1
	 * for AC coefficients.
	 */
	for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
		compptr = cinfo->cur_comp_info[ci];
		/* Initialize DC predictions to 0 */
		entropy->last_dc_val[ci] = 0;
		/* Get table index */
		if (is_DC_band) {
			if (cinfo->Ah != 0)       /* DC refinement needs no table */
				continue;
			tbl = compptr->dc_tbl_no;
		} else {
			entropy->ac_tbl_no = tbl = compptr->ac_tbl_no;
		}
		if (gather_statistics) {
			/* Check for invalid table index */
			/* (make_c_derived_tbl does this in the other path) */
			if (tbl < 0 || tbl >= NUM_HUFF_TBLS)
				ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tbl);
			/* Allocate and zero the statistics tables */
			/* Note that jpeg_gen_optimal_table expects 257 entries in each table! */
			if (entropy->count_ptrs[tbl] == NULL)
				entropy->count_ptrs[tbl] = (long *)
						(*cinfo->mem->alloc_small)((j_common_ptr) cinfo, JPOOL_IMAGE,
						                           257 * sizeof(long));
			MEMZERO(entropy->count_ptrs[tbl], 257 * sizeof(long));
		} else {
			/* Compute derived values for Huffman table */
			/* We may do this more than once for a table, but it's not expensive */
			jpeg_make_c_derived_tbl(cinfo, is_DC_band, tbl,
			                        &entropy->derived_tbls[tbl]);
		}
	}

	/* Initialize AC stuff */
	entropy->EOBRUN = 0;
	entropy->BE = 0;

	/* Initialize bit buffer to empty */
	entropy->put_buffer = 0;
	entropy->put_bits = 0;

	/* Initialize restart stuff */
	entropy->restarts_to_go = cinfo->restart_interval;
	entropy->next_restart_num = 0;
}


/* Outputting bytes to the file.
 * NB: these must be called only when actually outputting,
 * that is, entropy->gather_statistics == FALSE.
 */

/* Emit a byte */
#define emit_byte(entropy, val)  \
        { *(entropy)->next_output_byte++ = (JOCTET) (val);  \
          if (--(entropy)->free_in_buffer == 0)  \
            dump_buffer(entropy); }


LOCAL(void)
dump_buffer(phuff_entropy_ptr entropy)
/* Empty the output buffer; we do not support suspension in this module. */
{
	struct jpeg_destination_mgr *dest = entropy->cinfo->dest;

	if (!(*dest->empty_output_buffer)(entropy->cinfo))
		ERREXIT(entropy->cinfo, JERR_CANT_SUSPEND);
	/* After a successful buffer dump, must reset buffer pointers */
	entropy->next_output_byte = dest->next_output_byte;
	entropy->free_in_buffer = dest->free_in_buffer;
}


/* Outputting bits to the file */

/* Only the right 24 bits of put_buffer are used; the valid bits are
 * left-justified in this part.  At most 16 bits can be passed to emit_bits
 * in one call, and we never retain more than 7 bits in put_buffer
 * between calls, so 24 bits are sufficient.
 */

LOCAL(void)
emit_bits(phuff_entropy_ptr entropy, unsigned int code, int size)
/* Emit some bits, unless we are in gather mode */
{
	/* This routine is heavily used, so it's worth coding tightly. */
	register size_t put_buffer = (size_t) code;
	register int put_bits = entropy->put_bits;

	/* if size is 0, caller used an invalid Huffman table entry */
	if (size == 0)
		ERREXIT(entropy->cinfo, JERR_HUFF_MISSING_CODE);

	if (entropy->gather_statistics)
		return;                     /* do nothing if we're only getting stats */

	put_buffer &= (((size_t) 1) << size) - 1; /* mask off any extra bits in code */

	put_bits += size;             /* new number of bits in buffer */

	put_buffer <<= 24 - put_bits; /* align incoming bits */

	put_buffer |= entropy->put_buffer; /* and merge with old buffer contents */

	while (put_bits >= 8) {
		int c = (int) ((put_buffer >> 16) & 0xFF);

		emit_byte(entropy, c);
		if (c == 0xFF) {            /* need to stuff a zero byte? */
			emit_byte(entropy, 0);
		}
		put_buffer <<= 8;
		put_bits -= 8;
	}

	entropy->put_buffer = put_buffer; /* update variables */
	entropy->put_bits = put_bits;
}


LOCAL(void)
flush_bits(phuff_entropy_ptr entropy) {
	emit_bits(entropy, 0x7F, 7); /* fill any partial byte with ones */
	entropy->put_buffer = 0;     /* and reset bit-buffer to empty */
	entropy->put_bits = 0;
}


/*
 * Emit (or just count) a Huffman symbol.
 */

LOCAL(void)
emit_symbol(phuff_entropy_ptr entropy, int tbl_no, int symbol) {
	if (entropy->gather_statistics)
		entropy->count_ptrs[tbl_no][symbol]++;
	else {
		c_derived_tbl *tbl = entropy->derived_tbls[tbl_no];
		emit_bits(entropy, tbl->ehufco[symbol], tbl->ehufsi[symbol]);
	}
}


/*
 * Emit bits from a correction bit buffer.
 */

LOCAL(void)
emit_buffered_bits(phuff_entropy_ptr entropy, char *bufstart,
                   unsigned int nbits) {
	if (entropy->gather_statistics)
		return;                     /* no real work */

	while (nbits > 0) {
		emit_bits(entropy, (unsigned int) (*bufstart), 1);
		bufstart++;
		nbits--;
	}
}


/*
 * Emit any pending EOBRUN symbol.
 */

LOCAL(void)
emit_eobrun(phuff_entropy_ptr entropy) {
	register int temp, nbits;

	if (entropy->EOBRUN > 0) {    /* if there is any pending EOBRUN */
		temp = entropy->EOBRUN;
		nbits = 0;
		while ((temp >>= 1))
			nbits++;
		/* safety check: shouldn't happen given limited correction-bit buffer */
		if (nbits > 14)
			ERREXIT(entropy->cinfo, JERR_HUFF_MISSING_CODE);

		emit_symbol(entropy, entropy->ac_tbl_no, nbits << 4);
		if (nbits)
			emit_bits(entropy, entropy->EOBRUN, nbits);

		entropy->EOBRUN = 0;

		/* Emit any buffered correction bits */
		emit_buffered_bits(entropy, entropy->bit_buffer, entropy->BE);
		entropy->BE = 0;
	}
}


/*
 * Emit a restart marker & resynchronize predictions.
 */

LOCAL(void)
emit_restart(phuff_entropy_ptr entropy, int restart_num) {
	int ci;

	emit_eobrun(entropy);

	if (!entropy->gather_statistics) {
		flush_bits(entropy);
		emit_byte(entropy, 0xFF);
		emit_byte(entropy, JPEG_RST0 + restart_num);
	}

	if (entropy->cinfo->Ss == 0) {
		/* Re-initialize DC predictions to 0 */
		for (ci = 0; ci < entropy->cinfo->comps_in_scan; ci++)
			entropy->last_dc_val[ci] = 0;
	} else {
		/* Re-initialize all AC-related fields to 0 */
		entropy->EOBRUN = 0;
		entropy->BE = 0;
	}
}


/*
 * 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) {
	phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
	register int temp, temp2;
	register int nbits;
	int blkn, ci;
	int Al = cinfo->Al;
	JBLOCKROW block;
	jpeg_component_info *compptr;
	ISHIFT_TEMPS

	entropy->next_output_byte = cinfo->dest->next_output_byte;
	entropy->free_in_buffer = cinfo->dest->free_in_buffer;

	/* Emit restart marker if needed */
	if (cinfo->restart_interval)
		if (entropy->restarts_to_go == 0)
			emit_restart(entropy, entropy->next_restart_num);

	/* 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];

		/* Compute the DC value after the required point transform by Al.
		 * This is simply an arithmetic right shift.
		 */
		temp2 = IRIGHT_SHIFT((int) ((*block)[0]), Al);

		/* DC differences are figured on the point-transformed values. */
		temp = temp2 - entropy->last_dc_val[ci];
		entropy->last_dc_val[ci] = temp2;

		/* Encode the DC coefficient difference per section G.1.2.1 */
		temp2 = temp;
		if (temp < 0) {
			temp = -temp;             /* temp is abs value of input */
			/* For a negative input, want temp2 = bitwise complement of abs(input) */
			/* This code assumes we are on a two's complement machine */
			temp2--;
		}

		/* Find the number of bits needed for the magnitude of the coefficient */
		nbits = 0;
		while (temp) {
			nbits++;
			temp >>= 1;
		}
		/* Check for out-of-range coefficient values.
		 * Since we're encoding a difference, the range limit is twice as much.
		 */
		if (nbits > MAX_COEF_BITS + 1)
			ERREXIT(cinfo, JERR_BAD_DCT_COEF);

		/* Count/emit the Huffman-coded symbol for the number of bits */
		emit_symbol(entropy, compptr->dc_tbl_no, nbits);

		/* Emit that number of bits of the value, if positive, */
		/* or the complement of its magnitude, if negative. */
		if (nbits)                  /* emit_bits rejects calls with size 0 */
			emit_bits(entropy, (unsigned int) temp2, nbits);
	}

	cinfo->dest->next_output_byte = entropy->next_output_byte;
	cinfo->dest->free_in_buffer = entropy->free_in_buffer;

	/* Update restart-interval state too */
	if (cinfo->restart_interval) {
		if (entropy->restarts_to_go == 0) {
			entropy->restarts_to_go = cinfo->restart_interval;
			entropy->next_restart_num++;
			entropy->next_restart_num &= 7;
		}
		entropy->restarts_to_go--;
	}

	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) {
	phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
	register int temp, temp2;
	register int nbits;
	register int r, k;
	int Se = cinfo->Se;
	int Al = cinfo->Al;
	JBLOCKROW block;

	entropy->next_output_byte = cinfo->dest->next_output_byte;
	entropy->free_in_buffer = cinfo->dest->free_in_buffer;

	/* Emit restart marker if needed */
	if (cinfo->restart_interval)
		if (entropy->restarts_to_go == 0)
			emit_restart(entropy, entropy->next_restart_num);

	/* Encode the MCU data block */
	block = MCU_data[0];

	/* Encode the AC coefficients per section G.1.2.2, fig. G.3 */

	r = 0;                        /* r = run length of zeros */

	for (k = cinfo->Ss; k <= Se; k++) {
		if ((temp = (*block)[jpeg_natural_order[k]]) == 0) {
			r++;
			continue;
		}
		/* 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; so the code is
		 * interwoven with finding the abs value (temp) and output bits (temp2).
		 */
		if (temp < 0) {
			temp = -temp;             /* temp is abs value of input */
			temp >>= Al;              /* apply the point transform */
			/* For a negative coef, want temp2 = bitwise complement of abs(coef) */
			temp2 = ~temp;
		} else {
			temp >>= Al;              /* apply the point transform */
			temp2 = temp;
		}
		/* Watch out for case that nonzero coef is zero after point transform */
		if (temp == 0) {
			r++;
			continue;
		}

		/* Emit any pending EOBRUN */
		if (entropy->EOBRUN > 0)
			emit_eobrun(entropy);
		/* if run length > 15, must emit special run-length-16 codes (0xF0) */
		while (r > 15) {
			emit_symbol(entropy, entropy->ac_tbl_no, 0xF0);
			r -= 16;
		}

		/* Find the number of bits needed for the magnitude of the coefficient */
		nbits = 1;                  /* there must be at least one 1 bit */
		while ((temp >>= 1))
			nbits++;
		/* Check for out-of-range coefficient values */
		if (nbits > MAX_COEF_BITS)
			ERREXIT(cinfo, JERR_BAD_DCT_COEF);

		/* Count/emit Huffman symbol for run length / number of bits */
		emit_symbol(entropy, entropy->ac_tbl_no, (r << 4) + nbits);

		/* Emit that number of bits of the value, if positive, */
		/* or the complement of its magnitude, if negative. */
		emit_bits(entropy, (unsigned int) temp2, nbits);

		r = 0;                      /* reset zero run length */
	}

	if (r > 0) {                  /* If there are trailing zeroes, */
		entropy->EOBRUN++;          /* count an EOB */
		if (entropy->EOBRUN == 0x7FFF)
			emit_eobrun(entropy);     /* force it out to avoid overflow */
	}

	cinfo->dest->next_output_byte = entropy->next_output_byte;
	cinfo->dest->free_in_buffer = entropy->free_in_buffer;

	/* Update restart-interval state too */
	if (cinfo->restart_interval) {
		if (entropy->restarts_to_go == 0) {
			entropy->restarts_to_go = cinfo->restart_interval;
			entropy->next_restart_num++;
			entropy->next_restart_num &= 7;
		}
		entropy->restarts_to_go--;
	}

	return TRUE;
}


/*
 * MCU encoding for DC successive approximation refinement scan.
 * Note: we assume such scans can be multi-component, although the spec
 * is not very clear on the point.
 */

METHODDEF(boolean)
encode_mcu_DC_refine(j_compress_ptr cinfo, JBLOCKROW *MCU_data) {
	phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
	register int temp;
	int blkn;
	int Al = cinfo->Al;
	JBLOCKROW block;

	entropy->next_output_byte = cinfo->dest->next_output_byte;
	entropy->free_in_buffer = cinfo->dest->free_in_buffer;

	/* Emit restart marker if needed */
	if (cinfo->restart_interval)
		if (entropy->restarts_to_go == 0)
			emit_restart(entropy, entropy->next_restart_num);

	/* Encode the MCU data blocks */
	for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
		block = MCU_data[blkn];

		/* We simply emit the Al'th bit of the DC coefficient value. */
		temp = (*block)[0];
		emit_bits(entropy, (unsigned int) (temp >> Al), 1);
	}

	cinfo->dest->next_output_byte = entropy->next_output_byte;
	cinfo->dest->free_in_buffer = entropy->free_in_buffer;

	/* Update restart-interval state too */
	if (cinfo->restart_interval) {
		if (entropy->restarts_to_go == 0) {
			entropy->restarts_to_go = cinfo->restart_interval;
			entropy->next_restart_num++;
			entropy->next_restart_num &= 7;
		}
		entropy->restarts_to_go--;
	}

	return TRUE;
}


/*
 * MCU encoding for AC successive approximation refinement scan.
 */

METHODDEF(boolean)
encode_mcu_AC_refine(j_compress_ptr cinfo, JBLOCKROW *MCU_data) {
	phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
	register int temp;
	register int r, k;
	int EOB;
	char *BR_buffer;
	unsigned int BR;
	int Se = cinfo->Se;
	int Al = cinfo->Al;
	JBLOCKROW block;
	int absvalues[DCTSIZE2];

	entropy->next_output_byte = cinfo->dest->next_output_byte;
	entropy->free_in_buffer = cinfo->dest->free_in_buffer;

	/* Emit restart marker if needed */
	if (cinfo->restart_interval)
		if (entropy->restarts_to_go == 0)
			emit_restart(entropy, entropy->next_restart_num);

	/* Encode the MCU data block */
	block = MCU_data[0];

	/* It is convenient to make a pre-pass to determine the transformed
	 * coefficients' absolute values and the EOB position.
	 */
	EOB = 0;
	for (k = cinfo->Ss; k <= Se; k++) {
		temp = (*block)[jpeg_natural_order[k]];
		/* 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 (temp < 0)
			temp = -temp;             /* temp is abs value of input */
		temp >>= Al;                /* apply the point transform */
		absvalues[k] = temp;        /* save abs value for main pass */
		if (temp == 1)
			EOB = k;                  /* EOB = index of last newly-nonzero coef */
	}

	/* Encode the AC coefficients per section G.1.2.3, fig. G.7 */

	r = 0;                        /* r = run length of zeros */
	BR = 0;                       /* BR = count of buffered bits added now */
	BR_buffer = entropy->bit_buffer + entropy->BE; /* Append bits to buffer */

	for (k = cinfo->Ss; k <= Se; k++) {
		if ((temp = absvalues[k]) == 0) {
			r++;
			continue;
		}

		/* Emit any required ZRLs, but not if they can be folded into EOB */
		while (r > 15 && k <= EOB) {
			/* emit any pending EOBRUN and the BE correction bits */
			emit_eobrun(entropy);
			/* Emit ZRL */
			emit_symbol(entropy, entropy->ac_tbl_no, 0xF0);
			r -= 16;
			/* Emit buffered correction bits that must be associated with ZRL */
			emit_buffered_bits(entropy, BR_buffer, BR);
			BR_buffer = entropy->bit_buffer; /* BE bits are gone now */
			BR = 0;
		}

		/* If the coef was previously nonzero, it only needs a correction bit.
		 * NOTE: a straight translation of the spec's figure G.7 would suggest
		 * that we also need to test r > 15.  But if r > 15, we can only get here
		 * if k > EOB, which implies that this coefficient is not 1.
		 */
		if (temp > 1) {
			/* The correction bit is the next bit of the absolute value. */
			BR_buffer[BR++] = (char) (temp & 1);
			continue;
		}

		/* Emit any pending EOBRUN and the BE correction bits */
		emit_eobrun(entropy);

		/* Count/emit Huffman symbol for run length / number of bits */
		emit_symbol(entropy, entropy->ac_tbl_no, (r << 4) + 1);

		/* Emit output bit for newly-nonzero coef */
		temp = ((*block)[jpeg_natural_order[k]] < 0) ? 0 : 1;
		emit_bits(entropy, (unsigned int) temp, 1);

		/* Emit buffered correction bits that must be associated with this code */
		emit_buffered_bits(entropy, BR_buffer, BR);
		BR_buffer = entropy->bit_buffer; /* BE bits are gone now */
		BR = 0;
		r = 0;                      /* reset zero run length */
	}

	if (r > 0 || BR > 0) {        /* If there are trailing zeroes, */
		entropy->EOBRUN++;          /* count an EOB */
		entropy->BE += BR;          /* concat my correction bits to older ones */
		/* We force out the EOB if we risk either:
		 * 1. overflow of the EOB counter;
		 * 2. overflow of the correction bit buffer during the next MCU.
		 */
		if (entropy->EOBRUN == 0x7FFF || entropy->BE > (MAX_CORR_BITS - DCTSIZE2 + 1))
			emit_eobrun(entropy);
	}

	cinfo->dest->next_output_byte = entropy->next_output_byte;
	cinfo->dest->free_in_buffer = entropy->free_in_buffer;

	/* Update restart-interval state too */
	if (cinfo->restart_interval) {
		if (entropy->restarts_to_go == 0) {
			entropy->restarts_to_go = cinfo->restart_interval;
			entropy->next_restart_num++;
			entropy->next_restart_num &= 7;
		}
		entropy->restarts_to_go--;
	}

	return TRUE;
}


/*
 * Finish up at the end of a Huffman-compressed progressive scan.
 */

METHODDEF(void)
finish_pass_phuff(j_compress_ptr cinfo) {
	phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;

	entropy->next_output_byte = cinfo->dest->next_output_byte;
	entropy->free_in_buffer = cinfo->dest->free_in_buffer;

	/* Flush out any buffered data */
	emit_eobrun(entropy);
	flush_bits(entropy);

	cinfo->dest->next_output_byte = entropy->next_output_byte;
	cinfo->dest->free_in_buffer = entropy->free_in_buffer;
}


/*
 * Finish up a statistics-gathering pass and create the new Huffman tables.
 */

METHODDEF(void)
finish_pass_gather_phuff(j_compress_ptr cinfo) {
	phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
	boolean is_DC_band;
	int ci, tbl;
	jpeg_component_info *compptr;
	JHUFF_TBL **htblptr;
	boolean did[NUM_HUFF_TBLS];

	/* Flush out buffered data (all we care about is counting the EOB symbol) */
	emit_eobrun(entropy);

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

	/* It's important not to apply jpeg_gen_optimal_table more than once
	 * per table, because it clobbers the input frequency counts!
	 */
	MEMZERO(did, sizeof(did));

	for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
		compptr = cinfo->cur_comp_info[ci];
		if (is_DC_band) {
			if (cinfo->Ah != 0)       /* DC refinement needs no table */
				continue;
			tbl = compptr->dc_tbl_no;
		} else {
			tbl = compptr->ac_tbl_no;
		}
		if (!did[tbl]) {
			if (is_DC_band)
				htblptr = &cinfo->dc_huff_tbl_ptrs[tbl];
			else
				htblptr = &cinfo->ac_huff_tbl_ptrs[tbl];
			if (*htblptr == NULL)
				*htblptr = jpeg_alloc_huff_table((j_common_ptr) cinfo);
			jpeg_gen_optimal_table(cinfo, *htblptr, entropy->count_ptrs[tbl]);
			did[tbl] = TRUE;
		}
	}
}


/*
 * Module initialization routine for progressive Huffman entropy encoding.
 */

GLOBAL(void)
jinit_phuff_encoder(j_compress_ptr cinfo) {
	phuff_entropy_ptr entropy;
	int i;

	entropy = (phuff_entropy_ptr)
			(*cinfo->mem->alloc_small)((j_common_ptr) cinfo, JPOOL_IMAGE,
			                           sizeof(phuff_entropy_encoder));
	cinfo->entropy = (struct jpeg_entropy_encoder *) entropy;
	entropy->pub.start_pass = start_pass_phuff;

	/* Mark tables unallocated */
	for (i = 0; i < NUM_HUFF_TBLS; i++) {
		entropy->derived_tbls[i] = NULL;
		entropy->count_ptrs[i] = NULL;
	}
	entropy->bit_buffer = NULL;   /* needed only in AC refinement scan */
}

#endif /* C_PROGRESSIVE_SUPPORTED */
