/* $Xorg: dg4.c,v 1.3 2000/08/17 19:47:38 cpqbld Exp $ */ /* AGE Logic - Oct 15 1995 - Larry Hare */ /**** module fax/g4.c ****/ /****************************************************************************** Copyright 1993, 1994,1998 The Open Group All Rights Reserved. The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE OPEN GROUP BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. 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Title to this software shall at all times remain with AGE Logic, Inc. ***************************************************************************** fax/g4.c -- DDXIE G4 fax decode technique/element Ben Fahy -- AGE Logic, Inc. May, 1993 *****************************************************************************/ #define _G4 #include "fax.h" #include "faxint.h" #include "bits.h" #include /* pick up the BITMAP_BIT_ORDER from Core X*/ /**********************************************************************/ int decode_g4(state) FaxState *state; { register int bitpos; register unsigned char *byteptr; register unsigned char *endptr; register int a0_color; register int a0_pos; register int goal; register int mode; /* could overload goal, but will resist */ register int length; register int width; int lines_found=0; int n_old_trans; int n_new_trans; int *old_trans; int *new_trans; int a0a1,a1a2; int length_acc=0; int last_b1_idx=0; int b1_pos,b2_pos; int rl; if (state == (FaxState *)NULL) return(-1); /* set up initial bitstream for the very first strip */ if (!state->bits.started) { if (state->strip_state != StripStateNew) { state->decoder_done = FAX_DECODE_DONE_ErrorBadStripper; return(-1); } state->bits.byteptr = (unsigned char *)state->strip; state->bits.endptr = state->bits.byteptr + state->strip_size-4; /* we will panic with four bytes to go */ state->bits.bitpos = 0; state->bits.started = 1; } localize_state(state); if (state->magic_needs) finish_magic(state->final); /* a magic strip was waiting for 1st word of next strip */ /*** Main Decoding Loop ***/ while(1) { switch(goal) { case FAX_GOAL_StartNewLine: /* if any data produced by previous states, write it out */ if (lines_found >= state->nl_sought) save_state_and_return(state); /* normal line initialization stuff */ a0_pos = -1; a0_color = WHITE; goal = FAX_GOAL_DetermineMode; reset_transitions(); break; case FAX_GOAL_DetermineMode: get_mode_and_length(mode,length,byteptr,bitpos,endptr); goal = mode; /* our goal is now to handle whatever mode we're in! */ if (mode != FAX_MODE_Unknown) adjust_bitstream_8(length,byteptr,bitpos,endptr); break; case FAX_GOAL_HandleHoriz: length_acc=0; goal = FAX_GOAL_AccumulateA0A1; /* in case I run out of data while getting a0-a1 distance */ case FAX_GOAL_AccumulateA0A1: get_a0a1(FAX_GOAL_RecordA0A1); /* If we have to return for data before getting the */ /* whole a0a1 distance, we want to return to the a0a1 */ /* accumulate state when we reenter the decoder. If */ /* adjusting the bitstream forces us to return after */ /* getting the last part of the a0a1 distance, then */ /* we want to jump to state FAX_GOAL_RecordA0A1 when */ /* we reenter the decoder. */ case FAX_GOAL_RecordA0A1: a0a1 = length_acc; length_acc=0; goal = FAX_GOAL_AccumulateA1A2; /* in case I run out of data while getting a1-a2 distance */ case FAX_GOAL_AccumulateA1A2: get_a1a2(FAX_GOAL_FinishHoriz); /* If we have to return for data before getting the */ /* whole a1a2 distance, we want to return to the a1a2 */ /* accumulate state when we reenter the decoder. If */ /* adjusting the bitstream forces us to return after */ /* getting the last part of the a1a2 distance, then */ /* we want to jump to state FAX_GOAL_FinishHoriz when */ /* we reenter the decoder. */ case FAX_GOAL_FinishHoriz: a1a2 = length_acc; if (a0_pos < 0) { /* at start of line, a0a1 is the number of white pixels, */ /* which is also the index on the line where white->black */ new_trans[n_new_trans++] = a0a1; new_trans[n_new_trans] = a0_pos = a0a1 + a1a2; ++n_new_trans; } else { /* in middle of the line, a0a1 is run-length, so * a1_pos = a0_pos + a0a1, a2_pos = a1_pos + a1a2 * * 0 1 2 3 4 5 6 7 8 9 A B C D * |w |w |w |b |b |b |b |b |w | | | | | * a0 a1 a2 */ new_trans[n_new_trans++] = a0_pos + a0a1; new_trans[n_new_trans] = a0_pos = a0_pos + a0a1 + a1a2; ++n_new_trans; } if (a0_pos >= width) { if (a0_pos > width) { state->decoder_done = FAX_DECODE_DONE_ErrorPastWidth; save_state_and_return(state); } goal = FAX_GOAL_StartNewLine; FlushLineData(); break; } else goal = FAX_GOAL_DetermineMode; break; case FAX_MODE_Pass: if (!n_old_trans) { /* line above all white */ state->decoder_done = FAX_DECODE_DONE_ErrorPassAboveAllWhite; save_state_and_return(state); } find_b2pos(a0_pos,a0_color,n_old_trans,old_trans); a0_pos = b2_pos; if (a0_pos < 0) { FlushLineData(); goal = FAX_GOAL_StartNewLine; break; } if (a0_pos >= width) { state->decoder_done = FAX_DECODE_DONE_ErrorBadA0pos; save_state_and_return(state); } goal = FAX_GOAL_DetermineMode; break; case FAX_GOAL_HandleVertL3: case FAX_GOAL_HandleVertL2: case FAX_GOAL_HandleVertL1: case FAX_GOAL_HandleVert0: case FAX_GOAL_HandleVertR1: case FAX_GOAL_HandleVertR2: case FAX_GOAL_HandleVertR3: if (n_old_trans) { /* line above not all white */ find_b1pos(a0_pos,a0_color,n_old_trans,old_trans); if (b1_pos < 0) { if (goal > FAX_GOAL_HandleVert0) { state->decoder_done = FAX_DECODE_DONE_ErrorBadGoal; save_state_and_return(state); } b1_pos = width; } } else { /* line above was all white. Since b1 was first non-white */ /* b1 is imaginary transition off right edge. */ b1_pos = width; } /* ok, we are guaranteed that 0 <= b1_pos <= width */ /* set a0_pos = a1_pos, which is relative to b1_pos */ a0_pos = b1_pos + (goal-FAX_GOAL_HandleVert0); a0_color = 1-a0_color; new_trans[n_new_trans++] = a0_pos > 0 ? a0_pos : 0; if (a0_pos >= width) { FlushLineData(); goal = FAX_GOAL_StartNewLine; } else { /* not at eol yet */ goal = FAX_GOAL_DetermineMode; } break; default: state->decoder_done = FAX_DECODE_DONE_ErrorBadGoal; save_state_and_return(state); break; } /* end of switch */ } /*** End, Main Decoding Loop ***/ } /**** module fax/g4.c ****/