| 1 | /* (c) GPL 2007 Karel 'Clock' Kulhavy, Twibright Labs */ |
| 2 | |
| 3 | #define MIN(x,y) ((x)<(y)?(x):(y)) |
| 4 | #define MAX(x,y) ((x)>(y)?(x):(y)) |
| 5 | |
| 6 | #define BORDER 2 /* In pixels. Thickness of the border */ |
| 7 | #define CHALF 3 /* Size of the cross half. Size of the cross is CHALF*2 x CHALF*2. |
| 8 | */ |
| 9 | #define CPITCH 24 /* Distance between cross centers */ |
| 10 | |
| 11 | /* XCROSSES A4 65, US Letter 67. */ |
| 12 | #define XCROSSES 32 /* Number of crosses horizontally */ |
| 13 | /* YCROSSES A4 93, US Letter 87. */ |
| 14 | #define YCROSSES 46 /* Number of crosses vertically */ |
| 15 | |
| 16 | #define DATA_WIDTH (CPITCH*(XCROSSES-1)+2*CHALF) /* The rectangle occupied by |
| 17 | the data and crosses */ |
| 18 | #define DATA_HEIGHT (CPITCH*(YCROSSES-1)+2*CHALF) |
| 19 | #define WIDTH (2*BORDER+DATA_WIDTH) /* In pixels, including the border */ |
| 20 | /* In pixels, including the border and the label */ |
| 21 | |
| 22 | #define TEXT_WIDTH 13 /* Width of a single letter */ |
| 23 | |
| 24 | /* Definitions for seq2xy */ |
| 25 | |
| 26 | /* Properties of the narrow horizontal strip, with crosses */ |
| 27 | #define NARROWHEIGHT (2*CHALF) |
| 28 | #define GAPWIDTH (CPITCH-2*CHALF) |
| 29 | #define NARROWWIDTH (GAPWIDTH*(XCROSSES-1)) /* Useful width */ |
| 30 | #define NARROWPIXELS (NARROWHEIGHT*NARROWWIDTH) /* Useful pixels */ |
| 31 | |
| 32 | /* Properties of the wide horizontal strip, without crosses */ |
| 33 | #define WIDEHEIGHT GAPWIDTH |
| 34 | #define WIDEWIDTH (WIDTH-2*BORDER) |
| 35 | #define WIDEPIXELS (WIDEHEIGHT*WIDEWIDTH) |
| 36 | |
| 37 | /* Amount of raw payload pixels in one narrow-wide strip pair */ |
| 38 | #define REPHEIGHT (NARROWHEIGHT+WIDEHEIGHT) |
| 39 | #define REPPIXELS (WIDEPIXELS+NARROWPIXELS) |
| 40 | |
| 41 | /* Total bits before hamming including the unused */ |
| 42 | #define TOTALBITS ((long)REPPIXELS*(YCROSSES-1)+NARROWPIXELS) |
| 43 | |
| 44 | /* Hamming codes with parity */ |
| 45 | #define FEC_ORDER 1 /* Can be 2 to 5 inclusive. |
| 46 | 5 is 26/32, |
| 47 | 4 is 11/16, |
| 48 | 3 is 4/8, |
| 49 | 2 is 4/1 |
| 50 | 1 is golay codes */ |
| 51 | #if FEC_ORDER==1 |
| 52 | /* Golay */ |
| 53 | #define FEC_LARGEBITS 24 |
| 54 | #define FEC_SMALLBITS 12 |
| 55 | #else |
| 56 | /* Hamming */ |
| 57 | #define FEC_LARGEBITS (1<<FEC_ORDER) |
| 58 | #define FEC_SMALLBITS (FEC_LARGEBITS-1-FEC_ORDER) |
| 59 | #endif |
| 60 | |
| 61 | /* Hamming net channel capacity */ |
| 62 | #define FEC_SYMS (TOTALBITS/FEC_LARGEBITS) |
| 63 | #define NETBITS (FEC_SYMS*FEC_SMALLBITS) /* Net payload bits */ |
| 64 | #define USEDBITS (FEC_SYMS*FEC_LARGEBITS) /* Used raw bits to store |
| 65 | Hamming symbols */ |
| 66 | |
| 67 | /* Functions from common.c */ |
| 68 | extern unsigned long parity(unsigned long in); |
| 69 | extern int is_cross(unsigned x, unsigned y); |
| 70 | extern void seq2xy(int *x, int *y, unsigned seq); |
| 71 | |
| 72 | /* Counts number of '1' bits */ |
| 73 | unsigned ones(unsigned long in); |
| 74 | |
| 75 | /* Golay codes */ |
| 76 | unsigned long golay(unsigned long in); |
| 77 | extern unsigned long golay_codes[4096]; |