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  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.
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      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
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#ifndef BITBUF2_H
#define BITBUF2_H

#include "igzip_lib.h"

/* bit buffer types
 * BITBUF8: (e) Always write 8 bytes of data
 * BITBUFB: (b) Always write data
 */
#if !(defined(USE_BITBUFB) || defined(USE_BITBUF8) || defined(USE_BITBUF_ELSE))
# define USE_BITBUFB
#endif

#if defined (__unix__) || (__APPLE__) || (__MINGW32__)
#define _mm_stream_si64x(dst, src) *((uint64_t*)dst) = src
#else
#include <intrin.h>
#endif

#ifdef _WIN64
#pragma warning(disable: 4996)
#endif

#ifdef _MSC_VER
#define inline __inline
#endif


/* MAX_BITBUF_BIT WRITE is the maximum number of bits than can be safely written
 * by consecutive calls of write_bits. Note this assumes the bitbuf is in a
 * state that is possible at the exit of write_bits */
#ifdef USE_BITBUF8 /*Write bits safe */
# define MAX_BITBUF_BIT_WRITE 63
#elif defined(USE_BITBUFB) /* Write bits always */
# define MAX_BITBUF_BIT_WRITE 56
#else /* USE_BITBUF_ELSE */
# define MAX_BITBUF_BIT_WRITE 56
#endif


static
 inline void construct(struct BitBuf2 *me)
{
	me->m_bits = 0;
	me->m_bit_count = 0;
	me->m_out_buf = me->m_out_start = me->m_out_end = NULL;
}

static inline void init(struct BitBuf2 *me)
{
	me->m_bits = 0;
	me->m_bit_count = 0;
}

static inline void set_buf(struct BitBuf2 *me, unsigned char *buf, unsigned int len)
{
	unsigned int slop = 8;
	me->m_out_buf = me->m_out_start = buf;
	me->m_out_end = buf + len - slop;
}

static inline int is_full(struct BitBuf2 *me)
{
	return (me->m_out_buf > me->m_out_end);
}

static inline uint8_t * buffer_ptr(struct BitBuf2 *me)
{
	return me->m_out_buf;
}

static inline uint32_t buffer_used(struct BitBuf2 *me)
{
	return (uint32_t)(me->m_out_buf - me->m_out_start);
}

static inline uint32_t buffer_bits_used(struct BitBuf2 *me)
{
	return (8 * (uint32_t)(me->m_out_buf - me->m_out_start) + me->m_bit_count);
}

static inline void flush_bits(struct BitBuf2 *me)
{
	uint32_t bits;
	_mm_stream_si64x((int64_t *) me->m_out_buf, me->m_bits);
	bits = me->m_bit_count & ~7;
	me->m_bit_count -= bits;
	me->m_out_buf += bits/8;
	me->m_bits >>= bits;

}

static inline void check_space(struct BitBuf2 *me, uint32_t num_bits)
{
	/* Checks if bitbuf has num_bits extra space and flushes the bytes in
	 * the bitbuf if it doesn't. */
	if (63 - me->m_bit_count < num_bits)
		flush_bits(me);
}

static inline void write_bits_unsafe(struct BitBuf2 *me, uint64_t code, uint32_t count)
{
	me->m_bits |= code << me->m_bit_count;
	me->m_bit_count += count;
}

static inline void write_bits(struct BitBuf2 *me, uint64_t code, uint32_t count)
{
#ifdef USE_BITBUF8 /*Write bits safe */
	me->m_bits |= code << me->m_bit_count;
	me->m_bit_count += count;
	if (me->m_bit_count >= 64) {
		_mm_stream_si64x((int64_t *) me->m_out_buf, me->m_bits);
		me->m_out_buf += 8;
		me->m_bit_count -= 64;
		me->m_bits = code >> (count - me->m_bit_count);
	}
#elif defined(USE_BITBUFB) /* Write bits always */
	/* Assumes there is space to fit code into m_bits. */
	me->m_bits |= code << me->m_bit_count;
	me->m_bit_count += count;
	if (me->m_bit_count >= 8)
		flush_bits(me);
#else /* USE_BITBUF_ELSE */
	check_space(me, count);
	write_bits_unsafe(me, code, count);
#endif

}

/* Can write up to 8 bytes to output buffer */
static inline void flush(struct BitBuf2 *me)
{
	uint32_t bytes;
	if (me->m_bit_count) {
		_mm_stream_si64x((int64_t *) me->m_out_buf, me->m_bits);
		bytes = (me->m_bit_count + 7) / 8;
		me->m_out_buf += bytes;
	}
	me->m_bits = 0;
	me->m_bit_count = 0;
}

#endif //BITBUF2_H
