/* $Xorg: dtiffpb.c,v 1.3 2000/08/17 19:47:38 cpqbld Exp $ */ /* AGE Logic - Oct 15 1995 - Larry Hare */ /**** module fax/tiffpb.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. Except as contained in this notice, the name of The Open Group shall not be used in advertising or otherwise to promote the sale, use or other dealings in this Software without prior written authorization from The Open Group. NOTICE This software is being provided by AGE Logic, Inc. under the following license. By obtaining, using and/or copying this software, you agree that you have read, understood, and will comply with these terms and conditions: Permission to use, copy, modify, distribute and sell this software and its documentation for any purpose and without fee or royalty and to grant others any or all rights granted herein is hereby granted, provided that you agree to comply with the following copyright notice and statements, including the disclaimer, and that the same appears on all copies and derivative works of the software and documentation you make. "Copyright 1993, 1994 by AGE Logic, Inc." THIS SOFTWARE IS PROVIDED "AS IS". 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Title to this software shall at all times remain with AGE Logic, Inc. ***************************************************************************** fax/tiffpb.c -- DDXIE TIFF Packbits decode technique/element Packbits is output-type independent. The compression algorithm just compresses a stream. The 'strip_size' parameter should be how many bytes long the strip is... Coding assumption: it is always valid to do val = *byteptr++; But any code which does this is responsible for making sure the next access will also be valid. Otherwise, we should save state and return. Ben Fahy -- AGE Logic, Inc. Sept, 1993 *****************************************************************************/ /* the folling define causes extra stuff to be saved in state recorder */ #define _PBits #include "fax.h" #include "faxint.h" #include "bits.h" #include "xiemd.h" /* by decree of PackBits spec */ /**********************************************************************/ int decode_tiffpb(state) FaxState *state; { register int a0_color,a0_pos; register unsigned char *byteptr; register unsigned char *endptr; register int goal; register int width,rnd_width; register int rl; register int lines_found=0; int length_acc=0; /*** output line stuff ***/ register unsigned char *olp; register int i,a0_in_bytes; 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; /* record end of input strip */ state->bits.bitpos = 0; state->bits.started = 1; } if (state->magic_needs) { if (state->strip_state == StripStateNew) { state->strip_state = StripStateInUse; state->bits.byteptr = (unsigned char *)state->strip; state->bits.endptr = state->bits.byteptr + state->strip_size; /* record end of input strip */ state->bits.bitpos = 0; state->bits.started = 1; } else { /* no new strip?? But... I *need* more data! */ state->decoder_done = FAX_DECODE_DONE_ErrorBadMagic; return(lines_found); } state->magic_needs = 0; } localize_state(state); rnd_width = 8 * ((width+7)/8); olp = (unsigned char *) state->o_lines[lines_found]; /*** Main Decoding Loop ***/ while(1) { switch(goal) { case PB_GOAL_StartNewLine: if (lines_found >= state->nl_sought) { save_state_and_return(state); } a0_pos = 0; olp = (unsigned char *) state->o_lines[lines_found]; goal = PB_GOAL_GetRunLength; break; case PB_GOAL_GetRunLength: /*** Basic Packbits algorithm: code = *((signed char *)byteptr++); if (0 <= code && code <= 127) ===> length = code + 1; if (-127 <= code && code < 0) ===> length = 1 - code; else ===> length = 0 We can make things a little quicker (and avoid signed char compiler issues) if we simply look for whether the high bit is on or off, and then compute the result directly. Thus, if code && 0x80 => -128 <= code < 0 0x80 + foo = -128 + foo so length = 1 - code = 1 - (-128 + foo) = 129 - foo. note foo=0 is code for runlength 0 (fill) The positive case is even easier. ***/ if (byteptr >= endptr) { state->magic_needs = 1; state->strip_state = StripStateDone; save_state_and_return(state); } if (*byteptr & 0x80) { /* -128 <= code < 0 */ register int foo = 0x7f & *byteptr; if (foo) { length_acc = 129 - foo ; goal = PB_GOAL_GetRepeatByte; } else { length_acc = 0; /* -128 => code = 0 */ } } else { /* 0 <= code <= 127 */ length_acc = 1 + *byteptr; goal = PB_GOAL_GetLiteralBytes; } ++byteptr; /* make sure all the pixels fit on this output line */ if (8*length_acc + a0_pos > rnd_width ) { state->decoder_done = FAX_DECODE_DONE_ErrorPastWidth; save_state_and_return(state); } break; case PB_GOAL_GetLiteralBytes: /* Important Note!! we are guaranteed that output line has enough space to hold output pixels here. We checked in the GetRunLength state. However, it is possible we may run out of input bytes, in which case we may have to save state and return. */ a0_in_bytes = a0_pos / 8; while (length_acc > 0) { if (byteptr >= endptr) { a0_pos = a0_in_bytes << 3; state->magic_needs = 1; state->strip_state = StripStateDone; save_state_and_return(state); } a0_color = *byteptr++; length_acc--; #if (IMAGE_BYTE_ORDER == MSBFirst) olp[a0_in_bytes++] = a0_color; #else olp[a0_in_bytes++] = _ByteReverseTable[a0_color]; #endif } a0_pos = a0_in_bytes << 3; if (a0_pos >= width) { ++lines_found; goal = PB_GOAL_StartNewLine; } else goal = PB_GOAL_GetRunLength; break; case PB_GOAL_GetRepeatByte: if (byteptr >= endptr) { state->magic_needs = 1; state->strip_state = StripStateDone; save_state_and_return(state); } a0_color = *byteptr++; /* Important Note!! we are guaranteed that output line has enough space to hold output pixels here. We checked in the GetRunLength state */ a0_in_bytes = a0_pos / 8; for (i=0; i= width) { ++lines_found; goal = PB_GOAL_StartNewLine; } else goal = PB_GOAL_GetRunLength; break; default: state->decoder_done = FAX_DECODE_DONE_ErrorBadGoal; save_state_and_return(state); } /* end of switch */ } /* end of main decoding loop */ } /**** module fax/tiffpb.c ****/