src/zlib-ng/inflate_p.h

/* inflate_p.h -- Private inline functions and macros shared with more than one deflate method
 *
 */

#ifndef INFLATE_P_H
#define INFLATE_P_H

/*
 *   Macros shared by inflate() and inflateBack()
 */

/* check function to use adler32() for zlib or crc32() for gzip */
#ifdef GUNZIP
#  define UPDATE(check, buf, len) \
    (state->flags ? PREFIX(crc32)(check, buf, len) : functable.adler32(check, buf, len))
#else
#  define UPDATE(check, buf, len) functable.adler32(check, buf, len)
#endif

/* check macros for header crc */
#ifdef GUNZIP
#  define CRC2(check, word) \
    do { \
        hbuf[0] = (unsigned char)(word); \
        hbuf[1] = (unsigned char)((word) >> 8); \
        check = PREFIX(crc32)(check, hbuf, 2); \
    } while (0)

#  define CRC4(check, word) \
    do { \
        hbuf[0] = (unsigned char)(word); \
        hbuf[1] = (unsigned char)((word) >> 8); \
        hbuf[2] = (unsigned char)((word) >> 16); \
        hbuf[3] = (unsigned char)((word) >> 24); \
        check = PREFIX(crc32)(check, hbuf, 4); \
    } while (0)
#endif

/* Load registers with state in inflate() for speed */
#define LOAD() \
    do { \
        put = strm->next_out; \
        left = strm->avail_out; \
        next = strm->next_in; \
        have = strm->avail_in; \
        hold = state->hold; \
        bits = state->bits; \
    } while (0)

/* Restore state from registers in inflate() */
#define RESTORE() \
    do { \
        strm->next_out = put; \
        strm->avail_out = left; \
        strm->next_in = (z_const unsigned char *)next; \
        strm->avail_in = have; \
        state->hold = hold; \
        state->bits = bits; \
    } while (0)

/* Clear the input bit accumulator */
#define INITBITS() \
    do { \
        hold = 0; \
        bits = 0; \
    } while (0)

/* Ensure that there is at least n bits in the bit accumulator.  If there is
   not enough available input to do that, then return from inflate()/inflateBack(). */
#define NEEDBITS(n) \
    do { \
        while (bits < (unsigned)(n)) \
            PULLBYTE(); \
    } while (0)

/* Return the low n bits of the bit accumulator (n < 16) */
#define BITS(n) \
    (hold & ((1U << (unsigned)(n)) - 1))

/* Remove n bits from the bit accumulator */
#define DROPBITS(n) \
    do { \
        hold >>= (n); \
        bits -= (unsigned)(n); \
    } while (0)

/* Remove zero to seven bits as needed to go to a byte boundary */
#define BYTEBITS() \
    do { \
        hold >>= bits & 7; \
        bits -= bits & 7; \
    } while (0)

#endif