bitext()

static int fl::third_party::bitext ( JDEC * jd, unsigned int nbit )

static

Definition at line 432 of file tjpgd.cpp.hpp.

{
    size_t dc = jd->dctr;
    uint8_t *dp = jd->dptr;
    unsigned int d, flg = 0;
 
#if JD_FASTDECODE == 0
    uint8_t mbit = jd->dbit;
 
    d = 0;
    do {
        if (!mbit) {            /* Next byte? */
            if (!dc) {          /* No input data is available, re-fill input buffer */
                dp = jd->inbuf;    /* Top of input buffer */
                dc = jd->infunc(jd, dp, JD_SZBUF);
                if (!dc) return 0 - (int)JDR_INP;    /* Err: read error or wrong stream termination */
            } else {
                dp++;           /* Next data ptr */
            }
            dc--;               /* Decrement number of available bytes */
            if (flg) {          /* In flag sequence? */
                flg = 0;        /* Exit flag sequence */
                if (*dp != 0) return 0 - (int)JDR_FMT1; /* Err: unexpected flag is detected (may be collapted data) */
                *dp = 0xFF;     /* The flag is a data 0xFF */
            } else {
                if (*dp == 0xFF) {      /* Is start of flag sequence? */
                    flg = 1; continue;  /* Enter flag sequence */
                }
            }
            mbit = 0x80;        /* Read from MSB */
        }
        d <<= 1;    /* Get a bit */
        if (*dp & mbit) d |= 1;
        mbit >>= 1;
        nbit--;
    } while (nbit);
 
    jd->dbit = mbit; jd->dctr = dc; jd->dptr = dp;
    return (int)d;
 
#else
    unsigned int wbit = jd->dbit % 32;
    uint32_t w = jd->wreg & ((1UL << wbit) - 1);
 
 
    while (wbit < nbit) {   /* Prepare nbit bits into the working register */
        if (jd->marker) {
            d = 0xFF;   /* Input stream stalled, generate stuff bits */
        } else {
            if (!dc) {  /* Buffer empty, re-fill input buffer */
                dp = jd->inbuf;    /* Top of input buffer */
                dc = jd->infunc(jd, dp, JD_SZBUF);
                if (!dc) return 0 - (int)JDR_INP;    /* Err: read error or wrong stream termination */
            }
            d = *dp++; dc--;
            if (flg) {      /* In flag sequence? */
                flg = 0;    /* Exit flag sequence */
                if (d != 0) jd->marker = d; /* Not an escape of 0xFF but a marker */
                d = 0xFF;
            } else {
                if (d == 0xFF) {        /* Is start of flag sequence? */
                    flg = 1; continue;  /* Enter flag sequence, get trailing byte */
                }
            }
        }
        w = w << 8 | d; /* Get 8 bits into the working register */
        wbit += 8;
    }
    jd->wreg = w; jd->dbit = wbit - nbit;
    jd->dctr = dc; jd->dptr = dp;
 
    return (int)(w >> ((wbit - nbit) % 32));
#endif
}

References FL_NOEXCEPT, JD_SZBUF, JDR_FMT1, and JDR_INP.

Referenced by mcu_load().

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