bitwise.h

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/* Copyright (C) 1998 Oregon Graduate Institute of Science & Technology
 * 
 * See the file COPYRIGHT, which should have been supplied with this
 * package, for licensing details.  We may be contacted through email
 * at <quasar-help@cse.ogi.edu>.
 */

#include <sys/types.h>
#include <netinet/in.h>

#define SPEG_BW_START_RD(ptr) \
    int _BWleft_##ptr = 32 - (((int)ptr & 3) << 3); \
    u_int32_t _BWcur_##ptr = ntohl(*(u_int32_t*)(ptr -= (int)ptr & 3)) << (32 - _BWleft_##ptr)

#define SPEG_BW_END_RD(ptr) \
    (ptr += (39 - _BWleft_##ptr) >> 3)

#define SPEG_BW_GETN(ptr, dest, n) \
    do { \
        dest = _BWcur_##ptr >> (32 - n); \
        if ((_BWleft_##ptr -= n) <= 0) { \
            ptr += 4; \
            _BWcur_##ptr = ntohl(*(u_int32_t*)ptr); \
            if (_BWleft_##ptr != 0) { \
                dest |= _BWcur_##ptr >> (32 + _BWleft_##ptr); \
                _BWcur_##ptr <<= -_BWleft_##ptr; \
            } \
            _BWleft_##ptr += 32; \
        } \
        else _BWcur_##ptr <<= n; \
    } while (0)

#define SPEG_BW_FLUSHN(ptr, n) \
    do { \
        if ((_BWleft_##ptr -= n) <= 0) { \
            ptr += 4; \
            _BWcur_##ptr = ntohl(*(u_int32_t*)ptr); \
            _BWcur_##ptr <<= -_BWleft_##ptr; \
            _BWleft_##ptr += 32; \
        } \
        else _BWcur_##ptr <<= n; \
    } while (0)

#define SPEG_BW_GETHUFFN(ptr, dest, sztab, szext, n) \
    do { \
        int _BWtmp_##ptr; \
        dest = _BWcur_##ptr >> (32 - n); \
        _BWtmp_##ptr = _BWleft_##ptr - sztab[dest]szext; \
        if (_BWtmp_##ptr <= 0) { \
            ptr += 4; \
            _BWcur_##ptr = ntohl(*(u_int32_t*)ptr); \
            if (_BWtmp_##ptr != 0) { \
                dest |= _BWcur_##ptr >> (32 + _BWleft_##ptr - n); \
                _BWleft_##ptr -= sztab[dest]szext; \
                _BWcur_##ptr <<= -_BWleft_##ptr; \
                _BWleft_##ptr += 32; \
            } \
            else _BWleft_##ptr = 32; \
        } \
        else { \
            _BWleft_##ptr = _BWtmp_##ptr; \
            _BWcur_##ptr <<= sztab[dest]szext; \
        } \
    } while (0)


#define SPEG_BW_START_WR(ptr) \
    int _BWleft_##ptr = 32 - (((int)ptr & 3) << 3); \
    u_int32_t _BWcur_##ptr = ntohl(*(u_int32_t*)(ptr -= (int)ptr & 3)) >> _BWleft_##ptr

#define SPEG_BW_END_WR(ptr) \
    do { \
        if (_BWleft_##ptr != 32) { \
            _BWcur_##ptr <<= _BWleft_##ptr; \
            _BWcur_##ptr |= (ntohl(*(u_int32_t*)ptr) & (((u_int32_t)1 << _BWleft_##ptr) - 1)); \
            *(u_int32_t*)ptr = htonl(_BWcur_##ptr); \
            (ptr += (39 - _BWleft_##ptr) >> 3); \
        } \
    } while (0)

#define SPEG_BW_END_WR_CLEAN(ptr) \
    do { \
        if (_BWleft_##ptr != 32) { \
            _BWcur_##ptr <<= _BWleft_##ptr; \
            *(u_int32_t*)ptr = htonl(_BWcur_##ptr); \
            (ptr += (39 - _BWleft_##ptr) >> 3); \
        } \
    } while (0)

#define SPEG_BW_PUTN(ptr, src, n) \
    do { \
        int _BWtmp_##ptr = _BWleft_##ptr; \
        u_int32_t _BWsav_##ptr; \
        if ((_BWleft_##ptr -= n) < 0) { \
            _BWsav_##ptr = (_BWcur_##ptr << _BWtmp_##ptr) | \
                (src >> -_BWleft_##ptr); \
        } \
        else if (n == 32) \
            _BWsav_##ptr = src; \
        else \
            _BWsav_##ptr = (_BWcur_##ptr << n) | src; \
        if (_BWleft_##ptr <= 0) { \
            _BWcur_##ptr = src; \
            *(u_int32_t*)ptr = htonl(_BWsav_##ptr); \
            ptr += 4; \
            _BWleft_##ptr += 32; \
        } \
        else _BWcur_##ptr = _BWsav_##ptr; \
    } while (0)

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