/************************************************************************** * * codeoffsets.c -- Functions which code the mark offsets * Copyright (C) 1994 Stuart Inglis * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program 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 General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. * * $Id$ * **************************************************************************/ #include "sysfuncs.h" #include "marklist.h" #include "arithcode.h" #include "utils.h" #define TOP_INC 2 #define MID_INC 1 #define BOT_INC 1 void EncodeOffsets (marklistptr symbol_list, int nsyms) { int xpos = 1, xneg = 1, ypos = 1, yneg = 1; marklistptr step; int found; int dox = 0, leveltop = 1, levelmid = 1, levelbot = 1; elemlist xlist, ylist; /* all previous offsets */ int p, f, t, xoff, yoff, symnum, count; elemlist *xcond, *ycond; /* previous offsets conditioned on symbol num */ xcond = (elemlist *) malloc (nsyms * sizeof (elemlist)); if (!xcond) error_msg ("EncodeOffsets", "Out of memory...", ""); ycond = (elemlist *) malloc (nsyms * sizeof (elemlist)); if (!ycond) error_msg ("EncodeOffsets", "Out of memory...", ""); for (t = 0; t < nsyms; t++) { xcond[t].head = ycond[t].head = NULL; xcond[t].tot = ycond[t].tot = 0; } xlist.head = NULL; xlist.tot = 0; ylist.head = NULL; ylist.tot = 0; for (step = symbol_list, count = 0; step; step = step->next, count++) { xoff = step->data.xoffset; yoff = step->data.yoffset; symnum = step->data.symnum; for (dox = 1; dox >= 0; dox--) { /* encode the offsets, x first then y */ if (dox) found = elem_find (&xcond[symnum], xoff, &p, &f, &t); else found = elem_find (&ycond[symnum], yoff, &p, &f, &t); if (found) { arithmetic_encode (0, leveltop, leveltop + levelmid + levelbot); leveltop += TOP_INC; arithmetic_encode (p, f, t); } else { if (dox) found = elem_find (&xlist, xoff, &p, &f, &t); else found = elem_find (&ylist, yoff, &p, &f, &t); if (found) { arithmetic_encode (leveltop, leveltop + levelmid, leveltop + levelmid + levelbot); levelmid += MID_INC; arithmetic_encode (p, f, t); } else { arithmetic_encode (leveltop + levelmid, leveltop + levelmid + levelbot, leveltop + levelmid + levelbot); levelbot += BOT_INC; if (dox) EncodeGammaSigned (xoff, &xpos, &xneg); else EncodeGammaSigned (yoff, &ypos, &yneg); } } if (dox) { elem_add (&xlist, xoff); elem_add (&xcond[symnum], xoff); } else { elem_add (&ylist, yoff); elem_add (&ycond[symnum], yoff); } if (leveltop + levelmid >= maxfrequency) { leveltop = (leveltop + 1) / 2; levelmid = (levelmid + 1) / 2; levelbot = (levelbot + 1) / 2; } } } for (t = 0; t < nsyms; t++) { elem_free (&xcond[t]); elem_free (&ycond[t]); } elem_free (&xlist); elem_free (&ylist); if (V) fprintf (stderr, "offset models: top %d, mid %d, bot %d\n", (leveltop - 1) / TOP_INC, (levelmid - 1) / MID_INC, (levelbot - 1) / BOT_INC); } void DecodeOffsets (marklistptr symbol_list, int nsyms) { int xpos = 1, xneg = 1, ypos = 1, yneg = 1; marklistptr step; int i, target, dox; int leveltop = 1, levelmid = 1, levelbot = 1; elemlist xlist, ylist; int p, f, t, xoff = 0, yoff = 0, symnum, count = 0; elemlist *xcond, *ycond; xcond = (elemlist *) malloc (nsyms * sizeof (elemlist)); if (!xcond) error_msg ("EncodeOffsets", "Out of memory...", ""); ycond = (elemlist *) malloc (nsyms * sizeof (elemlist)); if (!ycond) error_msg ("EncodeOffsets", "Out of memory...", ""); for (i = 0; i < nsyms; i++) { xcond[i].head = ycond[i].head = NULL; xcond[i].tot = ycond[i].tot = 0; } xlist.head = NULL; xlist.tot = 0; ylist.head = NULL; ylist.tot = 0; for (step = symbol_list, count = 0; step; step = step->next, count++) { symnum = step->data.symnum; for (dox = 1; dox >= 0; dox--) { /* decode x offset first, then y */ target = arithmetic_decode_target (leveltop + levelmid + levelbot); if (target < leveltop) { arithmetic_decode (0, leveltop, leveltop + levelmid + levelbot); leveltop += TOP_INC; if (dox) i = arithmetic_decode_target (xcond[symnum].tot); else i = arithmetic_decode_target (ycond[symnum].tot); if (dox) { elem_getrange (&xcond[symnum], i, &xoff); elem_find (&xcond[symnum], xoff, &p, &f, &t); } else { elem_getrange (&ycond[symnum], i, &yoff); elem_find (&ycond[symnum], yoff, &p, &f, &t); } arithmetic_decode (p, f, t); } else if (target < leveltop + levelmid) { arithmetic_decode (leveltop, leveltop + levelmid, leveltop + levelmid + levelbot); levelmid += MID_INC; if (dox) i = arithmetic_decode_target (xlist.tot); else i = arithmetic_decode_target (ylist.tot); if (dox) { elem_getrange (&xlist, i, &xoff); elem_find (&xlist, xoff, &p, &f, &t); } else { elem_getrange (&ylist, i, &yoff); elem_find (&ylist, yoff, &p, &f, &t); } arithmetic_decode (p, f, t); } else { arithmetic_decode (leveltop + levelmid, leveltop + levelmid + levelbot, leveltop + levelmid + levelbot); levelbot += BOT_INC; if (dox) xoff = DecodeGammaSigned (&xpos, &xneg); else yoff = DecodeGammaSigned (&ypos, &yneg); } if (dox) { step->data.xoffset = xoff; elem_add (&xlist, xoff); elem_add (&xcond[symnum], xoff); } else { step->data.yoffset = yoff; elem_add (&ylist, yoff); elem_add (&ycond[symnum], yoff); } if (leveltop + levelmid >= maxfrequency) { leveltop = (leveltop + 1) / 2; levelmid = (levelmid + 1) / 2; levelbot = (levelbot + 1) / 2; } } } for (t = 0; t < nsyms; t++) { elem_free (&xcond[t]); elem_free (&ycond[t]); } elem_free (&xlist); elem_free (&ylist); }