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Diffstat (limited to 'compface.h')
| -rw-r--r-- | compface.h | 172 |
1 files changed, 172 insertions, 0 deletions
diff --git a/compface.h b/compface.h new file mode 100644 index 0000000..fc4f486 --- /dev/null +++ b/compface.h @@ -0,0 +1,172 @@ +/* + * Compface - 48x48x1 image compression and decompression + * + * Copyright (c) James Ashton - Sydney University - June 1990. + * + * Written 11th November 1989. + * + * Permission is given to distribute these sources, as long as the + * copyright messages are not removed, and no monies are exchanged. + * + * No responsibility is taken for any errors on inaccuracies inherent + * either to the comments or the code of this program, but if reported + * to me, then an attempt will be made to fix them. + */ + +#ifndef COMPFACE_H +#define COMPFACE_H + +#include <setjmp.h> + +/* For all function declarations, if ANSI then use a prototype. */ + +#if defined(__STDC__) +#define P(args) args +#else /* ! __STDC__ */ +#define P(args) () +#endif /* STDC */ + +/* need to know how many bits per hexadecimal digit for io */ +#define BITSPERDIG 4 +extern char HexDigits[]; + +/* define the face size - 48x48x1 */ +#define WIDTH 48 +#define HEIGHT WIDTH + +/* total number of pixels and digits */ +#define PIXELS (WIDTH * HEIGHT) +#define DIGITS (PIXELS / BITSPERDIG) + +/* internal face representation - 1 char per pixel is faster */ +extern char F[PIXELS]; + +extern int compface_xbitmap; + +/* output formatting word lengths and line lengths */ +#define DIGSPERWORD 4 +#define WORDSPERLINE (WIDTH / DIGSPERWORD / BITSPERDIG) + +/* compressed output uses the full range of printable characters. + * in ascii these are in a contiguous block so we just need to know + * the first and last. The total number of printables is needed too */ +#define FIRSTPRINT '!' +#define LASTPRINT '~' +#define NUMPRINTS (LASTPRINT - FIRSTPRINT + 1) + +/* output line length for compressed data */ +#define MAXLINELEN 78 + +/* Portable, very large unsigned integer arithmetic is needed. + * Implementation uses arrays of WORDs. COMPs must have at least + * twice as many bits as WORDs to handle intermediate results */ +#define WORD unsigned char +#define COMP unsigned long +#define BITSPERWORD 8 +#define WORDCARRY (1 << BITSPERWORD) +#define WORDMASK (WORDCARRY - 1) +#define MAXWORDS ((PIXELS * 2 + BITSPERWORD - 1) / BITSPERWORD) + +typedef struct bigint +{ + int b_words; + WORD b_word[MAXWORDS]; +} BigInt; + +extern BigInt B; + +/* This is the guess the next pixel table. Normally there are 12 neighbour + * pixels used to give 1<<12 cases but in the upper left corner lesser + * numbers of neighbours are available, leading to 6231 different guesses */ +typedef struct guesses +{ + char g_00[1<<12]; + char g_01[1<<7]; + char g_02[1<<2]; + char g_10[1<<9]; + char g_20[1<<6]; + char g_30[1<<8]; + char g_40[1<<10]; + char g_11[1<<5]; + char g_21[1<<3]; + char g_31[1<<5]; + char g_41[1<<6]; + char g_12[1<<1]; + char g_22[1<<0]; + char g_32[1<<2]; + char g_42[1<<2]; +} Guesses; + +/* data.h was established by sampling over 1000 faces and icons */ +extern Guesses G; + +/* Data of varying probabilities are encoded by a value in the range 0 - 255. + * The probability of the data determines the range of possible encodings. + * Offset gives the first possible encoding of the range */ +typedef struct prob +{ + WORD p_range; + WORD p_offset; +} Prob; + +/* A stack of probability values */ +extern Prob *ProbBuf[PIXELS * 2]; +extern int NumProbs; + +/* Each face is encoded using 9 octrees of 16x16 each. Each level of the + * trees has varying probabilities of being white, grey or black. + * The table below is based on sampling many faces */ + +#define BLACK 0 +#define GREY 1 +#define WHITE 2 + +extern Prob levels[4][3]; + +/* At the bottom of the octree 2x2 elements are considered black if any + * pixel is black. The probabilities below give the distribution of the + * 16 possible 2x2 patterns. All white is not really a possibility and + * has a probability range of zero. Again, experimentally derived data */ +extern Prob freqs[16]; + +#define ERR_OK 0 /* successful completion */ +#define ERR_EXCESS 1 /* completed OK but some input was ignored */ +#define ERR_INSUFF -1 /* insufficient input. Bad face format? */ +#define ERR_INTERNAL -2 /* Arithmetic overflow or buffer overflow */ + +extern int status; + + +extern jmp_buf comp_env; + +int AllBlack P((char *, int, int)) ; +int AllWhite P((char *, int, int)) ; +int BigPop P((Prob *)) ; +int compface P((char *)) ; +int main P((int, char *[])) ; +int ReadBuf P(()) ; +int Same P((char *, int, int)) ; +int uncompface P((char *)) ; +int WriteBuf P(()) ; + +void BigAdd P((unsigned char)) ; +void BigClear P(()) ; +void BigDiv P((unsigned char, unsigned char *)) ; +void BigMul P((unsigned char)) ; +void BigPrint P(()) ; +void BigPush P((Prob *)) ; +void BigRead P((char *)) ; +void BigSub P((unsigned int)) ; +void BigWrite P((char *)) ; +void CompAll P((char *)) ; +void Compress P((char *, int, int, int)) ; +void GenFace P(()) ; +void PopGreys P((char *, int, int)) ; +void PushGreys P((char *, int, int)) ; +void ReadFace P((char *)) ; +void RevPush P((Prob *)) ; +void UnCompAll P((char *)) ; +void UnCompress P((char *, int, int, int)) ; +void UnGenFace P(()) ; +void WriteFace P((char *)) ; +#endif /*COMPFACE_H*/ |