mqc_dec_inl.h

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/*
 *    Copyright (C) 2016-2020 Grok Image Compression Inc.
 *
 *    This source code is free software: you can redistribute it and/or  modify
 *    it under the terms of the GNU Affero General Public License, version 3,
 *    as published by the Free Software Foundation.
 *
 *    This source code is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU Affero General Public License for more details.
 *
 *    You should have received a copy of the GNU Affero General Public License
 *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 *
 *    This source code incorporates work covered by the BSD 2-clause license.
 *    Please see the LICENSE file in the root directory for details.
 *
 */
 
#pragma once
 
/* For internal use of decode_macro() */
#define mpsexchange_dec_macro(d, curctx, a) \
{ \
    if (a < (*curctx)->qeval) { \
        d = (*curctx)->mps ^ 1; \
        *curctx = (*curctx)->nlps; \
    } else { \
        d = (*curctx)->mps; \
        *curctx = (*curctx)->nmps; \
    } \
}
 
/* For internal use of decode_macro() */
#define lpsexchange_dec_macro(d, curctx, a) \
{ \
    if (a < (*curctx)->qeval) { \
        a = (*curctx)->qeval; \
        d = (*curctx)->mps; \
        *curctx = (*curctx)->nmps; \
    } else { \
        a = (*curctx)->qeval; \
        d = (*curctx)->mps ^ 1; \
        *curctx = (*curctx)->nlps; \
    } \
}
 
static INLINE uint32_t mqc_raw_decode(mqcoder *mqc){
    if (mqc->ct == 0) {
        /* Given mqc_raw_init_dec() we know that at some point we will */
        /* have a 0xFF 0xFF artificial marker */
        if (mqc->c == 0xff) {
            if (*mqc->bp  > 0x8f) {
                mqc->c = 0xff;
                mqc->ct = 8;
            } else {
                mqc->c = *mqc->bp;
                mqc->bp ++;
                mqc->ct = 7;
            }
        } else {
            mqc->c = *mqc->bp;
            mqc->bp ++;
            mqc->ct = 8;
        }
    }
    mqc->ct--;
 
    return ((uint32_t)mqc->c >> mqc->ct) & 0x01U;
}
 
#define bytein_dec_macro(mqc, c, ct) \
{ \
        /* Given mqc_init_dec() we know that at some point we will */ \
        /* have a 0xFF 0xFF artificial marker */ \
        uint32_t l_c = *(mqc->bp + 1); \
        if (*mqc->bp == 0xff) { \
                if (l_c > 0x8f) { \
                        c += 0xff00; \
                        ct = 8; \
                        mqc->end_of_byte_stream_counter ++; \
                } else { \
                        mqc->bp++; \
                        c += l_c << 9; \
                        ct = 7; \
                } \
        } else { \
                mqc->bp++; \
                c += l_c << 8; \
                ct = 8; \
        } \
}
 
/* For internal use of decode_macro() */
#define renorm_dec_macro(mqc, a, c, ct) \
{ \
    do { \
        if (ct == 0) \
            bytein_dec_macro(mqc, c, ct); \
        a <<= 1; \
        c <<= 1; \
        ct--; \
    } while (a < A_MIN); \
}
 
#define decode_macro(d, mqc, curctx, a, c, ct) \
{ \
    /* Implements ISO 15444-1 C.3.2 Decoding a decision (DECODE) */ \
    a -= (*curctx)->qeval;  \
    uint32_t qeval_shift = (*curctx)->qeval << 16; \
    if (c < qeval_shift) {  \
        lpsexchange_dec_macro(d, curctx, a);  \
        renorm_dec_macro(mqc, a, c, ct);  \
    } else {  \
        c -= qeval_shift;  \
        if (a < A_MIN) { \
            mpsexchange_dec_macro(d, curctx, a); \
            renorm_dec_macro(mqc, a, c, ct); \
        } else { \
            d = (*curctx)->mps; \
        } \
    } \
}
 
static INLINE void mqc_bytein(mqcoder *const mqc){
    bytein_dec_macro(mqc, mqc->c, mqc->ct);
}
 
#define mqc_renormd(mqc) \
    renorm_dec_macro(mqc, mqc->a, mqc->c, mqc->ct)
 
#define mqc_decode(d, mqc) \
    decode_macro(d, mqc, mqc->curctx, mqc->a, mqc->c, mqc->ct)