xref: /isa-l/igzip/bitbuf2.h (revision 55fbfabfc60f1002bc8133b730a59f6abd22cfce)

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  modification, are permitted provided that the following conditions
  are met:
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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
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#ifndef BITBUF2_H
#define BITBUF2_H

#include "igzip_lib.h"
#include "unaligned.h"

#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 */
#define MAX_BITBUF_BIT_WRITE 56

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;
        store_le_u64(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;
}

/* Can write up to 8 bytes to output buffer */
static inline void
flush(struct BitBuf2 *me)
{
        uint32_t bytes;
        if (me->m_bit_count) {
                store_le_u64(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;
}

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)
{ /* Assumes there is space to fit code into m_bits. */
        me->m_bits |= code << me->m_bit_count;
        me->m_bit_count += count;
        flush_bits(me);
}

static inline void
write_bits_flush(struct BitBuf2 *me, uint64_t code, uint32_t count)
{ /* Assumes there is space to fit code into m_bits. */
        me->m_bits |= code << me->m_bit_count;
        me->m_bit_count += count;
        flush(me);
}

#endif // BITBUF2_H