• bitwriter.c
  • /* libFLAC - Free Lossless Audio Codec library
     * Copyright (C) 2000-2009  Josh Coalson
     * Copyright (C) 2011-2025  Xiph.Org Foundation
     *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     *
     * - Redistributions of source code must retain the above copyright
     * notice, this list of conditions and the following disclaimer.
     *
     * - Redistributions in binary form must reproduce the above copyright
     * notice, this list of conditions and the following disclaimer in the
     * documentation and/or other materials provided with the distribution.
     *
     * - Neither the name of the Xiph.org Foundation nor the names of its
     * contributors may be used to endorse or promote products derived from
     * this software without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     * A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR
     * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
     * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
     * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
     * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
     * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
     * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     */
    
    #ifdef HAVE_CONFIG_H
    #  include <config.h>
    #endif
    
    #include <stdlib.h>
    #include <string.h>
    #include "private/bitwriter.h"
    #include "private/crc.h"
    #include "private/format.h"
    #include "private/macros.h"
    #include "private/stream_encoder.h"
    #include "FLAC/assert.h"
    #include "share/alloc.h"
    #include "share/compat.h"
    #include "share/endswap.h"
    
    /* Things should be fastest when this matches the machine word size */
    /* WATCHOUT: if you change this you must also change the following #defines down to SWAP_BE_WORD_TO_HOST below to match */
    /* WATCHOUT: there are a few places where the code will not work unless bwword is >= 32 bits wide */
    
    #if (ENABLE_64_BIT_WORDS == 0)
    
    typedef FLAC__uint32 bwword;
    typedef FLAC__uint64 FLAC__bwtemp;
    #define FLAC__BYTES_PER_WORD 4		/* sizeof bwword */
    #define FLAC__BITS_PER_WORD 32
    #define FLAC__TEMP_BITS 64
    #define FLAC__HALF_TEMP_BITS 32
    /* SWAP_BE_WORD_TO_HOST swaps bytes in a bwword (which is always big-endian) if necessary to match host byte order */
    #if WORDS_BIGENDIAN
    #define SWAP_BE_WORD_TO_HOST(x) (x)
    #else
    #define SWAP_BE_WORD_TO_HOST(x) ENDSWAP_32(x)
    #endif
    
    #else
    
    typedef FLAC__uint64 bwword;
    typedef FLAC__uint64 FLAC__bwtemp;
    #define FLAC__BYTES_PER_WORD 8		/* sizeof bwword */
    #define FLAC__BITS_PER_WORD 64
    #define FLAC__TEMP_BITS 64
    #define FLAC__HALF_TEMP_BITS 32
    /* SWAP_BE_WORD_TO_HOST swaps bytes in a bwword (which is always big-endian) if necessary to match host byte order */
    #if WORDS_BIGENDIAN
    #define SWAP_BE_WORD_TO_HOST(x) (x)
    #else
    #define SWAP_BE_WORD_TO_HOST(x) ENDSWAP_64(x)
    #endif
    
    #endif
    
    /*
     * The default capacity here doesn't matter too much.  The buffer always grows
     * to hold whatever is written to it.  Usually the encoder will stop adding at
     * a frame or metadata block, then write that out and clear the buffer for the
     * next one.
     */
    static const uint32_t FLAC__BITWRITER_DEFAULT_CAPACITY = 32768u / sizeof(bwword); /* size in words */
    /* When growing, increment with 1/4th at a time */
    static const uint32_t FLAC__BITWRITER_DEFAULT_GROW_FRACTION = 2; /* means grow by >> 2 (1/4th) of current size */
    
    #define FLAC__WORDS_TO_BITS(words) ((words) * FLAC__BITS_PER_WORD)
    #define FLAC__TOTAL_BITS(bw) (FLAC__WORDS_TO_BITS((bw)->words) + (bw)->bits)
    
    struct FLAC__BitWriter {
    	bwword *buffer;
    	bwword accum; /* accumulator; bits are right-justified; when full, accum is appended to buffer */
    	uint32_t capacity; /* capacity of buffer in words */
    	uint32_t words; /* # of complete words in buffer */
    	uint32_t bits; /* # of used bits in accum */
    };
    
    /* * WATCHOUT: The current implementation only grows the buffer. */
    #ifndef __SUNPRO_C
    static
    #endif
    FLAC__bool bitwriter_grow_(FLAC__BitWriter *bw, uint32_t bits_to_add)
    {
    	uint32_t new_capacity;
    	bwword *new_buffer;
    
    	FLAC__ASSERT(0 != bw);
    	FLAC__ASSERT(0 != bw->buffer);
    
    	/* calculate total words needed to store 'bits_to_add' additional bits */
    	new_capacity = bw->words + ((bw->bits + bits_to_add + FLAC__BITS_PER_WORD - 1) / FLAC__BITS_PER_WORD);
    
    	/* it's possible (due to pessimism in the growth estimation that
    	 * leads to this call) that we don't actually need to grow
    	 */
    	if(bw->capacity >= new_capacity)
    		return true;
    
    	if(new_capacity * sizeof(bwword) > (1u << FLAC__STREAM_METADATA_LENGTH_LEN))
    		/* Requested new capacity is larger than the largest possible metadata block,
    		 * which is also larger than the largest sane framesize. That means something
    		 * went very wrong somewhere and previous checks failed.
    		 * To prevent chrashing, give up */
    		return false;
    
    	/* As reallocation can be quite expensive, grow exponentially */
    	if((new_capacity - bw->capacity) < (bw->capacity >> FLAC__BITWRITER_DEFAULT_GROW_FRACTION))
    		new_capacity = bw->capacity + (bw->capacity >> FLAC__BITWRITER_DEFAULT_GROW_FRACTION);
    
    	/* make sure we got everything right */
    	FLAC__ASSERT(new_capacity > bw->capacity);
    	FLAC__ASSERT(new_capacity >= bw->words + ((bw->bits + bits_to_add + FLAC__BITS_PER_WORD - 1) / FLAC__BITS_PER_WORD));
    
    	new_buffer = safe_realloc_nofree_mul_2op_(bw->buffer, sizeof(bwword), /*times*/new_capacity);
    	if(new_buffer == 0)
    		return false;
    	bw->buffer = new_buffer;
    	bw->capacity = new_capacity;
    	return true;
    }
    
    
    /***********************************************************************
     *
     * Class constructor/destructor
     *
     ***********************************************************************/
    
    FLAC__BitWriter *FLAC__bitwriter_new(void)
    {
    	FLAC__BitWriter *bw = calloc(1, sizeof(FLAC__BitWriter));
    	/* note that calloc() sets all members to 0 for us */
    	return bw;
    }
    
    void FLAC__bitwriter_delete(FLAC__BitWriter *bw)
    {
    	FLAC__ASSERT(0 != bw);
    
    	FLAC__bitwriter_free(bw);
    	free(bw);
    }
    
    /***********************************************************************
     *
     * Public class methods
     *
     ***********************************************************************/
    
    FLAC__bool FLAC__bitwriter_init(FLAC__BitWriter *bw)
    {
    	FLAC__ASSERT(0 != bw);
    
    	bw->words = bw->bits = 0;
    	bw->capacity = FLAC__BITWRITER_DEFAULT_CAPACITY;
    	bw->buffer = malloc(sizeof(bwword) * bw->capacity);
    	if(bw->buffer == 0)
    		return false;
    
    	return true;
    }
    
    void FLAC__bitwriter_free(FLAC__BitWriter *bw)
    {
    	FLAC__ASSERT(0 != bw);
    
    	if(0 != bw->buffer)
    		free(bw->buffer);
    	bw->buffer = 0;
    	bw->capacity = 0;
    	bw->words = bw->bits = 0;
    }
    
    void FLAC__bitwriter_clear(FLAC__BitWriter *bw)
    {
    	bw->words = bw->bits = 0;
    }
    
    FLAC__bool FLAC__bitwriter_get_write_crc16(FLAC__BitWriter *bw, FLAC__uint16 *crc)
    {
    	const FLAC__byte *buffer;
    	size_t bytes;
    
    	FLAC__ASSERT((bw->bits & 7) == 0); /* assert that we're byte-aligned */
    
    	if(!FLAC__bitwriter_get_buffer(bw, &buffer, &bytes))
    		return false;
    
    	*crc = (FLAC__uint16)FLAC__crc16(buffer, bytes);
    	FLAC__bitwriter_release_buffer(bw);
    	return true;
    }
    
    FLAC__bool FLAC__bitwriter_get_write_crc8(FLAC__BitWriter *bw, FLAC__byte *crc)
    {
    	const FLAC__byte *buffer;
    	size_t bytes;
    
    	FLAC__ASSERT((bw->bits & 7) == 0); /* assert that we're byte-aligned */
    
    	if(!FLAC__bitwriter_get_buffer(bw, &buffer, &bytes))
    		return false;
    
    	*crc = FLAC__crc8(buffer, bytes);
    	FLAC__bitwriter_release_buffer(bw);
    	return true;
    }
    
    FLAC__bool FLAC__bitwriter_is_byte_aligned(const FLAC__BitWriter *bw)
    {
    	return ((bw->bits & 7) == 0);
    }
    
    uint32_t FLAC__bitwriter_get_input_bits_unconsumed(const FLAC__BitWriter *bw)
    {
    	return FLAC__TOTAL_BITS(bw);
    }
    
    FLAC__bool FLAC__bitwriter_get_buffer(FLAC__BitWriter *bw, const FLAC__byte **buffer, size_t *bytes)
    {
    	FLAC__ASSERT((bw->bits & 7) == 0);
    	/* double protection */
    	if(bw->bits & 7)
    		return false;
    	/* if we have bits in the accumulator we have to flush those to the buffer first */
    	if(bw->bits) {
    		FLAC__ASSERT(bw->words <= bw->capacity);
    		if(bw->words == bw->capacity && !bitwriter_grow_(bw, FLAC__BITS_PER_WORD))
    			return false;
    		/* append bits as complete word to buffer, but don't change bw->accum or bw->bits */
    		bw->buffer[bw->words] = SWAP_BE_WORD_TO_HOST(bw->accum << (FLAC__BITS_PER_WORD-bw->bits));
    	}
    	/* now we can just return what we have */
    	*buffer = (FLAC__byte*)bw->buffer;
    	*bytes = (FLAC__BYTES_PER_WORD * bw->words) + (bw->bits >> 3);
    	return true;
    }
    
    void FLAC__bitwriter_release_buffer(FLAC__BitWriter *bw)
    {
    	/* nothing to do.  in the future, strict checking of a 'writer-is-in-
    	 * get-mode' flag could be added everywhere and then cleared here
    	 */
    	(void)bw;
    }
    
    inline FLAC__bool FLAC__bitwriter_write_zeroes(FLAC__BitWriter *bw, uint32_t bits)
    {
    	uint32_t n;
    
    	FLAC__ASSERT(0 != bw);
    	FLAC__ASSERT(0 != bw->buffer);
    
    	if(bits == 0)
    		return true;
    	/* slightly pessimistic size check but faster than "<= bw->words + (bw->bits+bits+FLAC__BITS_PER_WORD-1)/FLAC__BITS_PER_WORD" */
    	if(bw->capacity <= bw->words + bits && !bitwriter_grow_(bw, bits))
    		return false;
    	/* first part gets to word alignment */
    	if(bw->bits) {
    		n = flac_min(FLAC__BITS_PER_WORD - bw->bits, bits);
    		bw->accum <<= n;
    		bits -= n;
    		bw->bits += n;
    		if(bw->bits == FLAC__BITS_PER_WORD) {
    			bw->buffer[bw->words++] = SWAP_BE_WORD_TO_HOST(bw->accum);
    			bw->bits = 0;
    		}
    		else
    			return true;
    	}
    	/* do whole words */
    	while(bits >= FLAC__BITS_PER_WORD) {
    		bw->buffer[bw->words++] = 0;
    		bits -= FLAC__BITS_PER_WORD;
    	}
    	/* do any leftovers */
    	if(bits > 0) {
    		bw->accum = 0;
    		bw->bits = bits;
    	}
    	return true;
    }
    
    static inline FLAC__bool FLAC__bitwriter_write_raw_uint32_nocheck(FLAC__BitWriter *bw, FLAC__uint32 val, uint32_t bits)
    {
    	register uint32_t left;
    
    	/* WATCHOUT: code does not work with <32bit words; we can make things much faster with this assertion */
    	FLAC__ASSERT(FLAC__BITS_PER_WORD >= 32);
    
    	if(bw == 0 || bw->buffer == 0)
    		return false;
    
    	if (bits > 32)
    		return false;
    
    	if(bits == 0)
    		return true;
    
    	FLAC__ASSERT((bits == 32) || (val>>bits == 0));
    
    	/* slightly pessimistic size check but faster than "<= bw->words + (bw->bits+bits+FLAC__BITS_PER_WORD-1)/FLAC__BITS_PER_WORD" */
    	if(bw->capacity <= bw->words + bits && !bitwriter_grow_(bw, bits))
    		return false;
    
    	left = FLAC__BITS_PER_WORD - bw->bits;
    	if(bits < left) {
    		bw->accum <<= bits;
    		bw->accum |= val;
    		bw->bits += bits;
    	}
    	else if(bw->bits) { /* WATCHOUT: if bw->bits == 0, left==FLAC__BITS_PER_WORD and bw->accum<<=left is a NOP instead of setting to 0 */
    		bw->accum <<= left;
    		bw->accum |= val >> (bw->bits = bits - left);
    		bw->buffer[bw->words++] = SWAP_BE_WORD_TO_HOST(bw->accum);
    		bw->accum = val; /* unused top bits can contain garbage */
    	}
    	else { /* at this point bits == FLAC__BITS_PER_WORD == 32  and  bw->bits == 0 */
    		bw->buffer[bw->words++] = SWAP_BE_WORD_TO_HOST((bwword)val);
    	}
    
    	return true;
    }
    
    inline FLAC__bool FLAC__bitwriter_write_raw_uint32(FLAC__BitWriter *bw, FLAC__uint32 val, uint32_t bits)
    {
    	/* check that unused bits are unset */
    	if((bits < 32) && (val>>bits != 0))
    		return false;
    
    	return FLAC__bitwriter_write_raw_uint32_nocheck(bw, val, bits);
    }
    
    inline FLAC__bool FLAC__bitwriter_write_raw_int32(FLAC__BitWriter *bw, FLAC__int32 val, uint32_t bits)
    {
    	/* zero-out unused bits */
    	if(bits < 32)
    		val &= (~(0xffffffff << bits));
    
    	return FLAC__bitwriter_write_raw_uint32_nocheck(bw, (FLAC__uint32)val, bits);
    }
    
    inline FLAC__bool FLAC__bitwriter_write_raw_uint64(FLAC__BitWriter *bw, FLAC__uint64 val, uint32_t bits)
    {
    	/* this could be a little faster but it's not used for much */
    	if(bits > 32) {
    		return
    			FLAC__bitwriter_write_raw_uint32(bw, (FLAC__uint32)(val>>32), bits-32) &&
    			FLAC__bitwriter_write_raw_uint32_nocheck(bw, (FLAC__uint32)val, 32);
    	}
    	else
    		return FLAC__bitwriter_write_raw_uint32(bw, (FLAC__uint32)val, bits);
    }
    
    inline FLAC__bool FLAC__bitwriter_write_raw_int64(FLAC__BitWriter *bw, FLAC__int64 val, uint32_t bits)
    {
    	FLAC__uint64 uval = val;
    	/* zero-out unused bits */
    	if(bits < 64)
    		uval &= (~(UINT64_MAX << bits));
    	return FLAC__bitwriter_write_raw_uint64(bw, uval, bits);
    }
    
    inline FLAC__bool FLAC__bitwriter_write_raw_uint32_little_endian(FLAC__BitWriter *bw, FLAC__uint32 val)
    {
    	/* this doesn't need to be that fast as currently it is only used for vorbis comments */
    
    	if(!FLAC__bitwriter_write_raw_uint32_nocheck(bw, val & 0xff, 8))
    		return false;
    	if(!FLAC__bitwriter_write_raw_uint32_nocheck(bw, (val>>8) & 0xff, 8))
    		return false;
    	if(!FLAC__bitwriter_write_raw_uint32_nocheck(bw, (val>>16) & 0xff, 8))
    		return false;
    	if(!FLAC__bitwriter_write_raw_uint32_nocheck(bw, val>>24, 8))
    		return false;
    
    	return true;
    }
    
    inline FLAC__bool FLAC__bitwriter_write_byte_block(FLAC__BitWriter *bw, const FLAC__byte vals[], uint32_t nvals)
    {
    	uint32_t i;
    
    	/* grow capacity upfront to prevent constant reallocation during writes */
    	if(bw->capacity <= bw->words + nvals / (FLAC__BITS_PER_WORD / 8) + 1 && !bitwriter_grow_(bw, nvals * 8))
    		return false;
    
    	/* this could be faster but currently we don't need it to be since it's only used for writing metadata */
    	for(i = 0; i < nvals; i++) {
    		if(!FLAC__bitwriter_write_raw_uint32_nocheck(bw, (FLAC__uint32)(vals[i]), 8))
    			return false;
    	}
    
    	return true;
    }
    
    FLAC__bool FLAC__bitwriter_write_unary_unsigned(FLAC__BitWriter *bw, uint32_t val)
    {
    	if(val < 32)
    		return FLAC__bitwriter_write_raw_uint32_nocheck(bw, 1, ++val);
    	else
    		return
    			FLAC__bitwriter_write_zeroes(bw, val) &&
    			FLAC__bitwriter_write_raw_uint32_nocheck(bw, 1, 1);
    }
    
    #if 0 /* UNUSED */
    uint32_t FLAC__bitwriter_rice_bits(FLAC__int32 val, uint32_t parameter)
    {
    	FLAC__uint32 uval;
    
    	FLAC__ASSERT(parameter < 32);
    
    	/* fold signed to uint32_t; actual formula is: negative(v)? -2v-1 : 2v */
    	uval = val;
    	uval <<= 1;
    	uval ^= (val>>31);
    
    	return 1 + parameter + (uval >> parameter);
    }
    
    uint32_t FLAC__bitwriter_golomb_bits_signed(int val, uint32_t parameter)
    {
    	uint32_t bits, msbs, uval;
    	uint32_t k;
    
    	FLAC__ASSERT(parameter > 0);
    
    	/* fold signed to uint32_t */
    	if(val < 0)
    		uval = (uint32_t)(((-(++val)) << 1) + 1);
    	else
    		uval = (uint32_t)(val << 1);
    
    	k = FLAC__bitmath_ilog2(parameter);
    	if(parameter == 1u<<k) {
    		FLAC__ASSERT(k <= 30);
    
    		msbs = uval >> k;
    		bits = 1 + k + msbs;
    	}
    	else {
    		uint32_t q, r, d;
    
    		d = (1 << (k+1)) - parameter;
    		q = uval / parameter;
    		r = uval - (q * parameter);
    
    		bits = 1 + q + k;
    		if(r >= d)
    			bits++;
    	}
    	return bits;
    }
    
    uint32_t FLAC__bitwriter_golomb_bits_unsigned(uint32_t uval, uint32_t parameter)
    {
    	uint32_t bits, msbs;
    	uint32_t k;
    
    	FLAC__ASSERT(parameter > 0);
    
    	k = FLAC__bitmath_ilog2(parameter);
    	if(parameter == 1u<<k) {
    		FLAC__ASSERT(k <= 30);
    
    		msbs = uval >> k;
    		bits = 1 + k + msbs;
    	}
    	else {
    		uint32_t q, r, d;
    
    		d = (1 << (k+1)) - parameter;
    		q = uval / parameter;
    		r = uval - (q * parameter);
    
    		bits = 1 + q + k;
    		if(r >= d)
    			bits++;
    	}
    	return bits;
    }
    
    FLAC__bool FLAC__bitwriter_write_rice_signed(FLAC__BitWriter *bw, FLAC__int32 val, uint32_t parameter)
    {
    	uint32_t total_bits, interesting_bits, msbs;
    	FLAC__uint32 uval, pattern;
    
    	FLAC__ASSERT(0 != bw);
    	FLAC__ASSERT(0 != bw->buffer);
    	FLAC__ASSERT(parameter < 32);
    
    	/* fold signed to uint32_t; actual formula is: negative(v)? -2v-1 : 2v */
    	uval = val;
    	uval <<= 1;
    	uval ^= (val>>31);
    
    	msbs = uval >> parameter;
    	interesting_bits = 1 + parameter;
    	total_bits = interesting_bits + msbs;
    	pattern = 1 << parameter; /* the unary end bit */
    	pattern |= (uval & ((1<<parameter)-1)); /* the binary LSBs */
    
    	if(total_bits <= 32)
    		return FLAC__bitwriter_write_raw_uint32(bw, pattern, total_bits);
    	else
    		return
    			FLAC__bitwriter_write_zeroes(bw, msbs) && /* write the unary MSBs */
    			FLAC__bitwriter_write_raw_uint32(bw, pattern, interesting_bits); /* write the unary end bit and binary LSBs */
    }
    #endif /* UNUSED */
    
    #if (ENABLE_64_BIT_WORDS == 0)
    
    #define WIDE_ACCUM_TO_BW {  \
    	bw->accum = wide_accum >> FLAC__HALF_TEMP_BITS;  \
    	bw->buffer[bw->words++] = SWAP_BE_WORD_TO_HOST(bw->accum); \
    	wide_accum <<= FLAC__HALF_TEMP_BITS;  \
    	bitpointer += FLAC__HALF_TEMP_BITS;  \
    }
    
    #else
    
    #define WIDE_ACCUM_TO_BW {  \
    	FLAC__ASSERT(bw->bits % FLAC__HALF_TEMP_BITS == 0);  \
    	if(bw->bits == 0) {  \
    		bw->accum = wide_accum >> FLAC__HALF_TEMP_BITS;  \
    		wide_accum <<= FLAC__HALF_TEMP_BITS;  \
    		bw->bits = FLAC__HALF_TEMP_BITS;  \
    	}  \
    	else {  \
    		bw->accum <<= FLAC__HALF_TEMP_BITS;  \
    		bw->accum += wide_accum >> FLAC__HALF_TEMP_BITS;  \
    		bw->buffer[bw->words++] = SWAP_BE_WORD_TO_HOST(bw->accum);  \
    		wide_accum <<= FLAC__HALF_TEMP_BITS;  \
    		bw->bits = 0;  \
    	}  \
    	bitpointer += FLAC__HALF_TEMP_BITS;  \
    }
    
    #endif
    
    FLAC__bool FLAC__bitwriter_write_rice_signed_block(FLAC__BitWriter *bw, const FLAC__int32 *vals, uint32_t nvals, uint32_t parameter)
    {
    	const FLAC__uint32 mask1 = (FLAC__uint32)0xffffffff << parameter; /* we val|=mask1 to set the stop bit above it... */
    	const FLAC__uint32 mask2 = (FLAC__uint32)0xffffffff >> (31-parameter); /* ...then mask off the bits above the stop bit with val&=mask2 */
    	FLAC__uint32 uval;
    	const uint32_t lsbits = 1 + parameter;
    	uint32_t msbits, total_bits;
    	FLAC__bwtemp wide_accum = 0;
    	FLAC__uint32 bitpointer = FLAC__TEMP_BITS;
    
    	FLAC__ASSERT(0 != bw);
    	FLAC__ASSERT(0 != bw->buffer);
    	FLAC__ASSERT(parameter < 31);
    	/* WATCHOUT: code does not work with <32bit words; we can make things much faster with this assertion */
    	FLAC__ASSERT(FLAC__BITS_PER_WORD >= 32);
    #if (ENABLE_64_BIT_WORDS == 0)
    	if(bw->bits > 0) {
    		bitpointer -= bw->bits;
    		wide_accum = (FLAC__bwtemp)(bw->accum) << bitpointer;
    		bw->bits = 0;
    	}
    #else
    	if(bw->bits > 0 && bw->bits < FLAC__HALF_TEMP_BITS) {
    		bitpointer -= bw->bits;
    		wide_accum = bw->accum << bitpointer;
    		bw->bits = 0;
    	}
    	else if(bw->bits > FLAC__HALF_TEMP_BITS) {
    		bitpointer -= (bw->bits - FLAC__HALF_TEMP_BITS);
    		wide_accum = bw->accum << bitpointer;
    		bw->accum >>= (bw->bits - FLAC__HALF_TEMP_BITS);
    		bw->bits = FLAC__HALF_TEMP_BITS;
    	}
    #endif
    
    	/* Reserve one FLAC__TEMP_BITS per symbol, so checks for space are only necessary when very large symbols are encountered
    	 * this might be considered wasteful, but is only at most 8kB more than necessary for a blocksize of 4096 */
    	if(bw->capacity * FLAC__BITS_PER_WORD <= bw->words * FLAC__BITS_PER_WORD + nvals * FLAC__TEMP_BITS + bw->bits && !bitwriter_grow_(bw, nvals * FLAC__TEMP_BITS))
    		return false;
    
    	while(nvals) {
    		/* fold signed to uint32_t; actual formula is: negative(v)? -2v-1 : 2v */
    		uval = *vals;
    		uval <<= 1;
    		uval ^= (*vals>>31);
    
    		msbits = uval >> parameter;
    		total_bits = lsbits + msbits;
    
    		uval |= mask1; /* set stop bit */
    		uval &= mask2; /* mask off unused top bits */
    
    
    		if(total_bits <= bitpointer) {
    			/* There is room enough to store the symbol whole at once */
    			wide_accum |= (FLAC__bwtemp)(uval) << (bitpointer - total_bits);
    			bitpointer -= total_bits;
    			if(bitpointer <= FLAC__HALF_TEMP_BITS) {
    				/* A word is finished, copy the upper 32 bits of the wide_accum */
    				WIDE_ACCUM_TO_BW
    			}
    		}
    		else {
    			/* The symbol needs to be split. This code isn't used often */
    			/* First check for space in the bitwriter */
    			if(total_bits > FLAC__TEMP_BITS) {
    				FLAC__uint32 oversize_in_bits = total_bits - FLAC__TEMP_BITS;
    				FLAC__uint32 capacity_needed = bw->words * FLAC__BITS_PER_WORD + bw->bits + nvals * FLAC__TEMP_BITS + oversize_in_bits;
    				if(bw->capacity * FLAC__BITS_PER_WORD <= capacity_needed && !bitwriter_grow_(bw, nvals * FLAC__TEMP_BITS + oversize_in_bits))
    					return false;
    			}
    			if(msbits > bitpointer) {
    				/* We have a lot of 0 bits to write, first align with bitwriter word */
    				msbits -= bitpointer - FLAC__HALF_TEMP_BITS;
    				bitpointer = FLAC__HALF_TEMP_BITS;
    				WIDE_ACCUM_TO_BW
    				while(msbits > bitpointer) {
    					/* As the accumulator is already zero, we only need to
    					 * assign zeroes to the bitbuffer */
    					WIDE_ACCUM_TO_BW
    					bitpointer -= FLAC__HALF_TEMP_BITS;
    					msbits -= FLAC__HALF_TEMP_BITS;
    				}
    				/* The remaining bits are zero, and the accumulator already is zero,
    				 * so just subtract the number of bits from bitpointer. When storing,
    				 * we can also just store 0 */
    				bitpointer -= msbits;
    				if(bitpointer <= FLAC__HALF_TEMP_BITS)
    					WIDE_ACCUM_TO_BW
    			}
    			else {
    				bitpointer -= msbits;
    				if(bitpointer <= FLAC__HALF_TEMP_BITS)
    					WIDE_ACCUM_TO_BW
    			}
    			/* The lsbs + stop bit always fit 32 bit, so this code mirrors the code above */
                            wide_accum |= (FLAC__bwtemp)(uval) << (bitpointer - lsbits);
                            bitpointer -= lsbits;
                            if(bitpointer <= FLAC__HALF_TEMP_BITS) {
                                    /* A word is finished, copy the upper 32 bits of the wide_accum */
                                    WIDE_ACCUM_TO_BW
                            }
    		}
    		vals++;
    		nvals--;
    	}
    	/* Now fixup remainder of wide_accum */
    #if (ENABLE_64_BIT_WORDS == 0)
    	if(bitpointer < FLAC__TEMP_BITS) {
    		bw->accum = wide_accum >> bitpointer;
    		bw->bits = FLAC__TEMP_BITS - bitpointer;
    	}
    #else
    	if(bitpointer < FLAC__TEMP_BITS) {
    		if(bw->bits == 0) {
    			bw->accum = wide_accum >> bitpointer;
    			bw->bits = FLAC__TEMP_BITS - bitpointer;
    		}
    		else if (bw->bits == FLAC__HALF_TEMP_BITS) {
    			bw->accum <<= FLAC__TEMP_BITS - bitpointer;
    			bw->accum |= (wide_accum >> bitpointer);
    			bw->bits = FLAC__HALF_TEMP_BITS + FLAC__TEMP_BITS - bitpointer;
    		}
    		else {
    			FLAC__ASSERT(0);
    		}
    	}
    #endif
    
    
    	return true;
    }
    
    #if 0 /* UNUSED */
    FLAC__bool FLAC__bitwriter_write_golomb_signed(FLAC__BitWriter *bw, int val, uint32_t parameter)
    {
    	uint32_t total_bits, msbs, uval;
    	uint32_t k;
    
    	FLAC__ASSERT(0 != bw);
    	FLAC__ASSERT(0 != bw->buffer);
    	FLAC__ASSERT(parameter > 0);
    
    	/* fold signed to uint32_t */
    	if(val < 0)
    		uval = (uint32_t)(((-(++val)) << 1) + 1);
    	else
    		uval = (uint32_t)(val << 1);
    
    	k = FLAC__bitmath_ilog2(parameter);
    	if(parameter == 1u<<k) {
    		uint32_t pattern;
    
    		FLAC__ASSERT(k <= 30);
    
    		msbs = uval >> k;
    		total_bits = 1 + k + msbs;
    		pattern = 1 << k; /* the unary end bit */
    		pattern |= (uval & ((1u<<k)-1)); /* the binary LSBs */
    
    		if(total_bits <= 32) {
    			if(!FLAC__bitwriter_write_raw_uint32(bw, pattern, total_bits))
    				return false;
    		}
    		else {
    			/* write the unary MSBs */
    			if(!FLAC__bitwriter_write_zeroes(bw, msbs))
    				return false;
    			/* write the unary end bit and binary LSBs */
    			if(!FLAC__bitwriter_write_raw_uint32(bw, pattern, k+1))
    				return false;
    		}
    	}
    	else {
    		uint32_t q, r, d;
    
    		d = (1 << (k+1)) - parameter;
    		q = uval / parameter;
    		r = uval - (q * parameter);
    		/* write the unary MSBs */
    		if(!FLAC__bitwriter_write_zeroes(bw, q))
    			return false;
    		/* write the unary end bit */
    		if(!FLAC__bitwriter_write_raw_uint32(bw, 1, 1))
    			return false;
    		/* write the binary LSBs */
    		if(r >= d) {
    			if(!FLAC__bitwriter_write_raw_uint32(bw, r+d, k+1))
    				return false;
    		}
    		else {
    			if(!FLAC__bitwriter_write_raw_uint32(bw, r, k))
    				return false;
    		}
    	}
    	return true;
    }
    
    FLAC__bool FLAC__bitwriter_write_golomb_unsigned(FLAC__BitWriter *bw, uint32_t uval, uint32_t parameter)
    {
    	uint32_t total_bits, msbs;
    	uint32_t k;
    
    	FLAC__ASSERT(0 != bw);
    	FLAC__ASSERT(0 != bw->buffer);
    	FLAC__ASSERT(parameter > 0);
    
    	k = FLAC__bitmath_ilog2(parameter);
    	if(parameter == 1u<<k) {
    		uint32_t pattern;
    
    		FLAC__ASSERT(k <= 30);
    
    		msbs = uval >> k;
    		total_bits = 1 + k + msbs;
    		pattern = 1 << k; /* the unary end bit */
    		pattern |= (uval & ((1u<<k)-1)); /* the binary LSBs */
    
    		if(total_bits <= 32) {
    			if(!FLAC__bitwriter_write_raw_uint32(bw, pattern, total_bits))
    				return false;
    		}
    		else {
    			/* write the unary MSBs */
    			if(!FLAC__bitwriter_write_zeroes(bw, msbs))
    				return false;
    			/* write the unary end bit and binary LSBs */
    			if(!FLAC__bitwriter_write_raw_uint32(bw, pattern, k+1))
    				return false;
    		}
    	}
    	else {
    		uint32_t q, r, d;
    
    		d = (1 << (k+1)) - parameter;
    		q = uval / parameter;
    		r = uval - (q * parameter);
    		/* write the unary MSBs */
    		if(!FLAC__bitwriter_write_zeroes(bw, q))
    			return false;
    		/* write the unary end bit */
    		if(!FLAC__bitwriter_write_raw_uint32(bw, 1, 1))
    			return false;
    		/* write the binary LSBs */
    		if(r >= d) {
    			if(!FLAC__bitwriter_write_raw_uint32(bw, r+d, k+1))
    				return false;
    		}
    		else {
    			if(!FLAC__bitwriter_write_raw_uint32(bw, r, k))
    				return false;
    		}
    	}
    	return true;
    }
    #endif /* UNUSED */
    
    FLAC__bool FLAC__bitwriter_write_utf8_uint32(FLAC__BitWriter *bw, FLAC__uint32 val)
    {
    	FLAC__bool ok = 1;
    
    	FLAC__ASSERT(0 != bw);
    	FLAC__ASSERT(0 != bw->buffer);
    
    	if((val & 0x80000000) != 0) /* this version only handles 31 bits */
    		return false;
    
    	if(val < 0x80) {
    		return FLAC__bitwriter_write_raw_uint32_nocheck(bw, val, 8);
    	}
    	else if(val < 0x800) {
    		ok &= FLAC__bitwriter_write_raw_uint32_nocheck(bw, 0xC0 | (val>>6), 8);
    		ok &= FLAC__bitwriter_write_raw_uint32_nocheck(bw, 0x80 | (val&0x3F), 8);
    	}
    	else if(val < 0x10000) {
    		ok &= FLAC__bitwriter_write_raw_uint32_nocheck(bw, 0xE0 | (val>>12), 8);
    		ok &= FLAC__bitwriter_write_raw_uint32_nocheck(bw, 0x80 | ((val>>6)&0x3F), 8);
    		ok &= FLAC__bitwriter_write_raw_uint32_nocheck(bw, 0x80 | (val&0x3F), 8);
    	}
    	else if(val < 0x200000) {
    		ok &= FLAC__bitwriter_write_raw_uint32_nocheck(bw, 0xF0 | (val>>18), 8);
    		ok &= FLAC__bitwriter_write_raw_uint32_nocheck(bw, 0x80 | ((val>>12)&0x3F), 8);
    		ok &= FLAC__bitwriter_write_raw_uint32_nocheck(bw, 0x80 | ((val>>6)&0x3F), 8);
    		ok &= FLAC__bitwriter_write_raw_uint32_nocheck(bw, 0x80 | (val&0x3F), 8);
    	}
    	else if(val < 0x4000000) {
    		ok &= FLAC__bitwriter_write_raw_uint32_nocheck(bw, 0xF8 | (val>>24), 8);
    		ok &= FLAC__bitwriter_write_raw_uint32_nocheck(bw, 0x80 | ((val>>18)&0x3F), 8);
    		ok &= FLAC__bitwriter_write_raw_uint32_nocheck(bw, 0x80 | ((val>>12)&0x3F), 8);
    		ok &= FLAC__bitwriter_write_raw_uint32_nocheck(bw, 0x80 | ((val>>6)&0x3F), 8);
    		ok &= FLAC__bitwriter_write_raw_uint32_nocheck(bw, 0x80 | (val&0x3F), 8);
    	}
    	else {
    		ok &= FLAC__bitwriter_write_raw_uint32_nocheck(bw, 0xFC | (val>>30), 8);
    		ok &= FLAC__bitwriter_write_raw_uint32_nocheck(bw, 0x80 | ((val>>24)&0x3F), 8);
    		ok &= FLAC__bitwriter_write_raw_uint32_nocheck(bw, 0x80 | ((val>>18)&0x3F), 8);
    		ok &= FLAC__bitwriter_write_raw_uint32_nocheck(bw, 0x80 | ((val>>12)&0x3F), 8);
    		ok &= FLAC__bitwriter_write_raw_uint32_nocheck(bw, 0x80 | ((val>>6)&0x3F), 8);
    		ok &= FLAC__bitwriter_write_raw_uint32_nocheck(bw, 0x80 | (val&0x3F), 8);
    	}
    
    	return ok;
    }
    
    FLAC__bool FLAC__bitwriter_write_utf8_uint64(FLAC__BitWriter *bw, FLAC__uint64 val)
    {
    	FLAC__bool ok = 1;
    
    	FLAC__ASSERT(0 != bw);
    	FLAC__ASSERT(0 != bw->buffer);
    
    	if((val & FLAC__U64L(0xFFFFFFF000000000)) != 0) /* this version only handles 36 bits */
    		return false;
    
    	if(val < 0x80) {
    		return FLAC__bitwriter_write_raw_uint32_nocheck(bw, (FLAC__uint32)val, 8);
    	}
    	else if(val < 0x800) {
    		ok &= FLAC__bitwriter_write_raw_uint32_nocheck(bw, 0xC0 | (FLAC__uint32)(val>>6), 8);
    		ok &= FLAC__bitwriter_write_raw_uint32_nocheck(bw, 0x80 | (FLAC__uint32)(val&0x3F), 8);
    	}
    	else if(val < 0x10000) {
    		ok &= FLAC__bitwriter_write_raw_uint32_nocheck(bw, 0xE0 | (FLAC__uint32)(val>>12), 8);
    		ok &= FLAC__bitwriter_write_raw_uint32_nocheck(bw, 0x80 | (FLAC__uint32)((val>>6)&0x3F), 8);
    		ok &= FLAC__bitwriter_write_raw_uint32_nocheck(bw, 0x80 | (FLAC__uint32)(val&0x3F), 8);
    	}
    	else if(val < 0x200000) {
    		ok &= FLAC__bitwriter_write_raw_uint32_nocheck(bw, 0xF0 | (FLAC__uint32)(val>>18), 8);
    		ok &= FLAC__bitwriter_write_raw_uint32_nocheck(bw, 0x80 | (FLAC__uint32)((val>>12)&0x3F), 8);
    		ok &= FLAC__bitwriter_write_raw_uint32_nocheck(bw, 0x80 | (FLAC__uint32)((val>>6)&0x3F), 8);
    		ok &= FLAC__bitwriter_write_raw_uint32_nocheck(bw, 0x80 | (FLAC__uint32)(val&0x3F), 8);
    	}
    	else if(val < 0x4000000) {
    		ok &= FLAC__bitwriter_write_raw_uint32_nocheck(bw, 0xF8 | (FLAC__uint32)(val>>24), 8);
    		ok &= FLAC__bitwriter_write_raw_uint32_nocheck(bw, 0x80 | (FLAC__uint32)((val>>18)&0x3F), 8);
    		ok &= FLAC__bitwriter_write_raw_uint32_nocheck(bw, 0x80 | (FLAC__uint32)((val>>12)&0x3F), 8);
    		ok &= FLAC__bitwriter_write_raw_uint32_nocheck(bw, 0x80 | (FLAC__uint32)((val>>6)&0x3F), 8);
    		ok &= FLAC__bitwriter_write_raw_uint32_nocheck(bw, 0x80 | (FLAC__uint32)(val&0x3F), 8);
    	}
    	else if(val < 0x80000000) {
    		ok &= FLAC__bitwriter_write_raw_uint32_nocheck(bw, 0xFC | (FLAC__uint32)(val>>30), 8);
    		ok &= FLAC__bitwriter_write_raw_uint32_nocheck(bw, 0x80 | (FLAC__uint32)((val>>24)&0x3F), 8);
    		ok &= FLAC__bitwriter_write_raw_uint32_nocheck(bw, 0x80 | (FLAC__uint32)((val>>18)&0x3F), 8);
    		ok &= FLAC__bitwriter_write_raw_uint32_nocheck(bw, 0x80 | (FLAC__uint32)((val>>12)&0x3F), 8);
    		ok &= FLAC__bitwriter_write_raw_uint32_nocheck(bw, 0x80 | (FLAC__uint32)((val>>6)&0x3F), 8);
    		ok &= FLAC__bitwriter_write_raw_uint32_nocheck(bw, 0x80 | (FLAC__uint32)(val&0x3F), 8);
    	}
    	else {
    		ok &= FLAC__bitwriter_write_raw_uint32_nocheck(bw, 0xFE, 8);
    		ok &= FLAC__bitwriter_write_raw_uint32_nocheck(bw, 0x80 | (FLAC__uint32)((val>>30)&0x3F), 8);
    		ok &= FLAC__bitwriter_write_raw_uint32_nocheck(bw, 0x80 | (FLAC__uint32)((val>>24)&0x3F), 8);
    		ok &= FLAC__bitwriter_write_raw_uint32_nocheck(bw, 0x80 | (FLAC__uint32)((val>>18)&0x3F), 8);
    		ok &= FLAC__bitwriter_write_raw_uint32_nocheck(bw, 0x80 | (FLAC__uint32)((val>>12)&0x3F), 8);
    		ok &= FLAC__bitwriter_write_raw_uint32_nocheck(bw, 0x80 | (FLAC__uint32)((val>>6)&0x3F), 8);
    		ok &= FLAC__bitwriter_write_raw_uint32_nocheck(bw, 0x80 | (FLAC__uint32)(val&0x3F), 8);
    	}
    
    	return ok;
    }
    
    FLAC__bool FLAC__bitwriter_zero_pad_to_byte_boundary(FLAC__BitWriter *bw)
    {
    	/* 0-pad to byte boundary */
    	if(bw->bits & 7u)
    		return FLAC__bitwriter_write_zeroes(bw, 8 - (bw->bits & 7u));
    	else
    		return true;
    }
    
    /* These functions are declared inline in this file but are also callable as
     * externs from elsewhere.
     * According to the C99 spec, section 6.7.4, simply providing a function
     * prototype in a header file without 'inline' and making the function inline
     * in this file should be sufficient.
     * Unfortunately, the Microsoft VS compiler doesn't pick them up externally. To
     * fix that we add extern declarations here.
     */
    extern FLAC__bool FLAC__bitwriter_write_zeroes(FLAC__BitWriter *bw, uint32_t bits);
    extern FLAC__bool FLAC__bitwriter_write_raw_uint32(FLAC__BitWriter *bw, FLAC__uint32 val, uint32_t bits);
    extern FLAC__bool FLAC__bitwriter_write_raw_int32(FLAC__BitWriter *bw, FLAC__int32 val, uint32_t bits);
    extern FLAC__bool FLAC__bitwriter_write_raw_uint64(FLAC__BitWriter *bw, FLAC__uint64 val, uint32_t bits);
    extern FLAC__bool FLAC__bitwriter_write_raw_int64(FLAC__BitWriter *bw, FLAC__int64 val, uint32_t bits);
    extern FLAC__bool FLAC__bitwriter_write_raw_uint32_little_endian(FLAC__BitWriter *bw, FLAC__uint32 val);
    extern FLAC__bool FLAC__bitwriter_write_byte_block(FLAC__BitWriter *bw, const FLAC__byte vals[], uint32_t nvals);