jpc_t1dec.c

用C语言实现的JPEG编码

			jpc_sigpass_step(fp, frowstep, dp, bitpos, oneplushalf,
			  orient, mqdec, 0);
		}
	}
	return 0;
}

#define	jpc_rawsigpass_step(fp, frowstep, dp, oneplushalf, in, vcausalflag) \
{ \
	jpc_fix_t f = *(fp); \
	jpc_fix_t v; \
	if ((f & JPC_OTHSIGMSK) && !(f & (JPC_SIG | JPC_VISIT))) { \
		JPC_T1D_RAWGETBIT(in, v, "SIG", "ZC"); \
		if (v < 0) { \
			return -1; \
		} \
		if (v) { \
			JPC_T1D_RAWGETBIT(in, v, "SIG", "SC"); \
			if (v < 0) { \
				return -1; \
			} \
			JPC_UPDATEFLAGS4((fp), (frowstep), v, (vcausalflag)); \
			*(fp) |= JPC_SIG; \
			*(dp) = v ? (-oneplushalf) : (oneplushalf); \
		} \
		*(fp) |= JPC_VISIT; \
	} \
}

static int dec_rawsigpass(jpc_dec_t *dec, jpc_bitstream_t *in, int bitpos, int vcausalflag,
  jas_matrix_t *flags, jas_matrix_t *data)
{
	int i;
	int j;
	int k;
	int one;
	int half;
	int oneplushalf;
	int vscanlen;
	int width;
	int height;
	jpc_fix_t *fp;
	int frowstep;
	int fstripestep;
	jpc_fix_t *fstripestart;
	jpc_fix_t *fvscanstart;
	jpc_fix_t *dp;
	int drowstep;
	int dstripestep;
	jpc_fix_t *dstripestart;
	jpc_fix_t *dvscanstart;

	/* Avoid compiler warning about unused parameters. */
	dec = 0;

	width = jas_matrix_numcols(data);
	height = jas_matrix_numrows(data);
	frowstep = jas_matrix_rowstep(flags);
	drowstep = jas_matrix_rowstep(data);
	fstripestep = frowstep << 2;
	dstripestep = drowstep << 2;

	one = 1 << bitpos;
	half = one >> 1;
	oneplushalf = one | half;

	fstripestart = jas_matrix_getref(flags, 1, 1);
	dstripestart = jas_matrix_getref(data, 0, 0);
	for (i = height; i > 0; i -= 4, fstripestart += fstripestep,
	  dstripestart += dstripestep) {
		fvscanstart = fstripestart;
		dvscanstart = dstripestart;
		vscanlen = JAS_MIN(i, 4);
		for (j = width; j > 0; --j, ++fvscanstart, ++dvscanstart) {
			fp = fvscanstart;
			dp = dvscanstart;
			k = vscanlen;

			/* Process first sample in vertical scan. */
			jpc_rawsigpass_step(fp, frowstep, dp, oneplushalf,
			  in, vcausalflag);
			if (--k <= 0) {
				continue;
			}
			fp += frowstep;
			dp += drowstep;

			/* Process second sample in vertical scan. */
			jpc_rawsigpass_step(fp, frowstep, dp, oneplushalf,
			  in, 0);
			if (--k <= 0) {
				continue;
			}
			fp += frowstep;
			dp += drowstep;

			/* Process third sample in vertical scan. */
			jpc_rawsigpass_step(fp, frowstep, dp, oneplushalf,
			  in, 0);
			if (--k <= 0) {
				continue;
			}
			fp += frowstep;
			dp += drowstep;

			/* Process fourth sample in vertical scan. */
			jpc_rawsigpass_step(fp, frowstep, dp, oneplushalf,
			  in, 0);

		}
	}
	return 0;
}

/******************************************************************************\
* Code for refinement pass.
\******************************************************************************/

#define	jpc_refpass_step(fp, dp, poshalf, neghalf, mqdec, vcausalflag) \
{ \
	int v; \
	int t; \
	if (((*(fp)) & (JPC_SIG | JPC_VISIT)) == JPC_SIG) { \
		jpc_mqdec_setcurctx((mqdec), JPC_GETMAGCTXNO(*(fp))); \
		JPC_T1D_GETBITNOSKEW((mqdec), v, "REF", "MR"); \
		t = (v ? (poshalf) : (neghalf)); \
		*(dp) += (*(dp) < 0) ? (-t) : t; \
		*(fp) |= JPC_REFINE; \
	} \
}

static int dec_refpass(jpc_dec_t *dec, register jpc_mqdec_t *mqdec, int bitpos,
  int vcausalflag, jas_matrix_t *flags, jas_matrix_t *data)
{
	int i;
	int j;
	int vscanlen;
	int width;
	int height;
	int one;
	int poshalf;
	int neghalf;
	jpc_fix_t *fp;
	int frowstep;
	int fstripestep;
	jpc_fix_t *fstripestart;
	jpc_fix_t *fvscanstart;
	jpc_fix_t *dp;
	int drowstep;
	int dstripestep;
	jpc_fix_t *dstripestart;
	jpc_fix_t *dvscanstart;
	int k;

	/* Avoid compiler warning about unused parameters. */
	dec = 0;
	vcausalflag = 0;

	width = jas_matrix_numcols(data);
	height = jas_matrix_numrows(data);
	frowstep = jas_matrix_rowstep(flags);
	drowstep = jas_matrix_rowstep(data);
	fstripestep = frowstep << 2;
	dstripestep = drowstep << 2;

	one = 1 << bitpos;
	poshalf = one >> 1;
	neghalf = (bitpos > 0) ? (-poshalf) : (-1);

	fstripestart = jas_matrix_getref(flags, 1, 1);
	dstripestart = jas_matrix_getref(data, 0, 0);
	for (i = height; i > 0; i -= 4, fstripestart += fstripestep,
	  dstripestart += dstripestep) {
		fvscanstart = fstripestart;
		dvscanstart = dstripestart;
		vscanlen = JAS_MIN(i, 4);
		for (j = width; j > 0; --j, ++fvscanstart, ++dvscanstart) {
			fp = fvscanstart;
			dp = dvscanstart;
			k = vscanlen;

			/* Process first sample in vertical scan. */
			jpc_refpass_step(fp, dp, poshalf, neghalf, mqdec,
			  vcausalflag);
			if (--k <= 0) {
				continue;
			}
			fp += frowstep;
			dp += drowstep;

			/* Process second sample in vertical scan. */
			jpc_refpass_step(fp, dp, poshalf, neghalf, mqdec, 0);
			if (--k <= 0) {
				continue;
			}
			fp += frowstep;
			dp += drowstep;

			/* Process third sample in vertical scan. */
			jpc_refpass_step(fp, dp, poshalf, neghalf, mqdec, 0);
			if (--k <= 0) {
				continue;
			}
			fp += frowstep;
			dp += drowstep;

			/* Process fourth sample in vertical scan. */
			jpc_refpass_step(fp, dp, poshalf, neghalf, mqdec, 0);
		}
	}

	return 0;
}

#define	jpc_rawrefpass_step(fp, dp, poshalf, neghalf, in, vcausalflag) \
{ \
	jpc_fix_t v; \
	jpc_fix_t t; \
	if (((*(fp)) & (JPC_SIG | JPC_VISIT)) == JPC_SIG) { \
		JPC_T1D_RAWGETBIT(in, v, "REF", "MAGREF"); \
		if (v < 0) { \
			return -1; \
		} \
		t = (v ? poshalf : neghalf); \
		*(dp) += (*(dp) < 0) ? (-t) : t; \
		*(fp) |= JPC_REFINE; \
	} \
}

static int dec_rawrefpass(jpc_dec_t *dec, jpc_bitstream_t *in, int bitpos, int vcausalflag,
  jas_matrix_t *flags, jas_matrix_t *data)
{
	int i;
	int j;
	int k;
	int vscanlen;
	int width;
	int height;
	int one;
	int poshalf;
	int neghalf;
	jpc_fix_t *fp;
	int frowstep;
	int fstripestep;
	jpc_fix_t *fstripestart;
	jpc_fix_t *fvscanstart;
	jpc_fix_t *dp;
	int drowstep;
	int dstripestep;
	jpc_fix_t *dstripestart;
	jpc_fix_t *dvscanstart;

	/* Avoid compiler warning about unused parameters. */
	dec = 0;
	vcausalflag = 0;

	width = jas_matrix_numcols(data);
	height = jas_matrix_numrows(data);
	frowstep = jas_matrix_rowstep(flags);
	drowstep = jas_matrix_rowstep(data);
	fstripestep = frowstep << 2;
	dstripestep = drowstep << 2;

	one = 1 << bitpos;
	poshalf = one >> 1;
	neghalf = (bitpos > 0) ? (-poshalf) : (-1);

	fstripestart = jas_matrix_getref(flags, 1, 1);
	dstripestart = jas_matrix_getref(data, 0, 0);
	for (i = height; i > 0; i -= 4, fstripestart += fstripestep,
	  dstripestart += dstripestep) {
		fvscanstart = fstripestart;
		dvscanstart = dstripestart;
		vscanlen = JAS_MIN(i, 4);
		for (j = width; j > 0; --j, ++fvscanstart, ++dvscanstart) {
			fp = fvscanstart;
			dp = dvscanstart;
			k = vscanlen;

			/* Process first sample in vertical scan. */
			jpc_rawrefpass_step(fp, dp, poshalf, neghalf, in,
			  vcausalflag);
			if (--k <= 0) {
				continue;
			}
			fp += frowstep;
			dp += drowstep;

			/* Process second sample in vertical scan. */
			jpc_rawrefpass_step(fp, dp, poshalf, neghalf, in, 0);
			if (--k <= 0) {
				continue;
			}
			fp += frowstep;
			dp += drowstep;

			/* Process third sample in vertical scan. */
			jpc_rawrefpass_step(fp, dp, poshalf, neghalf, in, 0);
			if (--k <= 0) {
				continue;
			}
			fp += frowstep;
			dp += drowstep;

			/* Process fourth sample in vertical scan. */
			jpc_rawrefpass_step(fp, dp, poshalf, neghalf, in, 0);
		}
	}
	return 0;
}

/******************************************************************************\
* Code for cleanup pass.
\******************************************************************************/

#define	jpc_clnpass_step(f, fp, frowstep, dp, oneplushalf, orient, mqdec, flabel, plabel, vcausalflag) \
{ \
	int v; \
flabel \
	if (!((f) & (JPC_SIG | JPC_VISIT))) { \
		jpc_mqdec_setcurctx((mqdec), JPC_GETZCCTXNO((f), (orient))); \
		JPC_T1D_GETBIT((mqdec), v, "CLN", "ZC"); \
		if (v) { \
plabel \
			/* Coefficient is significant. */ \
			jpc_mqdec_setcurctx((mqdec), JPC_GETSCCTXNO(f)); \
			JPC_T1D_GETBIT((mqdec), v, "CLN", "SC"); \
			v ^= JPC_GETSPB(f); \
			*(dp) = (v) ? (-(oneplushalf)) : (oneplushalf); \
			JPC_UPDATEFLAGS4((fp), (frowstep), v, (vcausalflag)); \
			*(fp) |= JPC_SIG; \
		} \
	} \
	/* XXX - Is this correct?  Can aggregation cause some VISIT bits not to be reset?  Check. */ \
	*(fp) &= ~JPC_VISIT; \
}

static int dec_clnpass(jpc_dec_t *dec, register jpc_mqdec_t *mqdec, int bitpos, int orient,
  int vcausalflag, int segsymflag, jas_matrix_t *flags, jas_matrix_t *data)
{
	int i;
	int j;
	int k;
	int vscanlen;
	int v;
	int half;
	int runlen;
	int f;
	int width;
	int height;
	int one;
	int oneplushalf;

	jpc_fix_t *fp;
	int frowstep;
	int fstripestep;
	jpc_fix_t *fstripestart;
	jpc_fix_t *fvscanstart;

	jpc_fix_t *dp;
	int drowstep;
	int dstripestep;
	jpc_fix_t *dstripestart;
	jpc_fix_t *dvscanstart;

	/* Avoid compiler warning about unused parameters. */
	dec = 0;

	one = 1 << bitpos;
	half = one >> 1;
	oneplushalf = one | half;

	width = jas_matrix_numcols(data);
	height = jas_matrix_numrows(data);

	frowstep = jas_matrix_rowstep(flags);
	drowstep = jas_matrix_rowstep(data);
	fstripestep = frowstep << 2;
	dstripestep = drowstep << 2;

	fstripestart = jas_matrix_getref(flags, 1, 1);
	dstripestart = jas_matrix_getref(data, 0, 0);
	for (i = 0; i < height; i += 4, fstripestart += fstripestep,
	  dstripestart += dstripestep) {
		fvscanstart = fstripestart;
		dvscanstart = dstripestart;
		vscanlen = JAS_MIN(4, height - i);
		for (j = width; j > 0; --j, ++fvscanstart, ++dvscanstart) {
			fp = fvscanstart;
			if (vscanlen >= 4 && (!((*fp) & (JPC_SIG | JPC_VISIT |
			  JPC_OTHSIGMSK))) && (fp += frowstep, !((*fp) & (JPC_SIG |
			  JPC_VISIT | JPC_OTHSIGMSK))) && (fp += frowstep, !((*fp) &
			  (JPC_SIG | JPC_VISIT | JPC_OTHSIGMSK))) && (fp += frowstep,
			  !((*fp) & (JPC_SIG | JPC_VISIT | JPC_OTHSIGMSK)))) {

				jpc_mqdec_setcurctx(mqdec, JPC_AGGCTXNO);
				JPC_T1D_GETBIT(mqdec, v, "CLN", "AGG");
				if (!v) {
					continue;
				}
				jpc_mqdec_setcurctx(mqdec, JPC_UCTXNO);
				JPC_T1D_GETBITNOSKEW(mqdec, v, "CLN", "RL");
				runlen = v;
				JPC_T1D_GETBITNOSKEW(mqdec, v, "CLN", "RL");
				runlen = (runlen << 1) | v;
				f = *(fp = fvscanstart + frowstep * runlen);
				dp = dvscanstart + drowstep * runlen;
				k = vscanlen - runlen;
				switch (runlen) {
				case 0:
					goto clnpass_partial0;
					break;
				case 1:
					goto clnpass_partial1;
					break;
				case 2:
					goto clnpass_partial2;
					break;
				case 3:
					goto clnpass_partial3;
					break;
				}
			} else {
				f = *(fp = fvscanstart);
				dp = dvscanstart;
				k = vscanlen;
				goto clnpass_full0;
			}

			/* Process first sample in vertical scan. */
			jpc_clnpass_step(f, fp, frowstep, dp, oneplushalf, orient,
			  mqdec, clnpass_full0:, clnpass_partial0:,
			  vcausalflag);
			if (--k <= 0) {
				continue;
			}
			fp += frowstep;
			dp += drowstep;

			/* Process second sample in vertical scan. */
			f = *fp;
			jpc_clnpass_step(f, fp, frowstep, dp, oneplushalf, orient,
				mqdec, ;, clnpass_partial1:, 0);
			if (--k <= 0) {
				continue;
			}
			fp += frowstep;
			dp += drowstep;

			/* Process third sample in vertical scan. */
			f = *fp;
			jpc_clnpass_step(f, fp, frowstep, dp, oneplushalf, orient,
				mqdec, ;, clnpass_partial2:, 0);
			if (--k <= 0) {
				continue;
			}
			fp += frowstep;
			dp += drowstep;

			/* Process fourth sample in vertical scan. */
			f = *fp;
			jpc_clnpass_step(f, fp, frowstep, dp, oneplushalf, orient,
				mqdec, ;, clnpass_partial3:, 0);
		}
	}

	if (segsymflag) {
		int segsymval;
		segsymval = 0;
		jpc_mqdec_setcurctx(mqdec, JPC_UCTXNO);
		JPC_T1D_GETBITNOSKEW(mqdec, v, "CLN", "SEGSYM");
		segsymval = (segsymval << 1) | (v & 1);
		JPC_T1D_GETBITNOSKEW(mqdec, v, "CLN", "SEGSYM");
		segsymval = (segsymval << 1) | (v & 1);
		JPC_T1D_GETBITNOSKEW(mqdec, v, "CLN", "SEGSYM");
		segsymval = (segsymval << 1) | (v & 1);
		JPC_T1D_GETBITNOSKEW(mqdec, v, "CLN", "SEGSYM");
		segsymval = (segsymval << 1) | (v & 1);
		if (segsymval != 0xa) {
			fprintf(stderr, "warning: bad segmentation symbol\n");
		}
	}

	return 0;
}