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| Rev | Author | Line No. | Line |
|---|---|---|---|
| 54 | pj | 1 | /* VGAlib version 1.2 - (c) 1993 Tommy Frandsen */ |
| 2 | /* */ |
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| 3 | /* This library is free software; you can redistribute it and/or */ |
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| 4 | /* modify it without any restrictions. This library is distributed */ |
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| 5 | /* in the hope that it will be useful, but without any warranty. */ |
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| 6 | |||
| 7 | /* Multi-chipset support Copyright 1993 Harm Hanemaayer */ |
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| 8 | /* partially copyrighted (C) 1993 by Hartmut Schirmer */ |
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| 9 | |||
| 10 | #include <stdio.h> |
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| 11 | #include "vga.h" |
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| 12 | #include "libvga.h" |
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| 13 | |||
| 14 | #define ABS(a) (((a)<0) ? -(a) : (a)) |
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| 15 | |||
| 16 | int vga_drawline(int x1, int y1, int x2, int y2) |
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| 17 | { |
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| 18 | int dx = x2 - x1; |
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| 19 | int dy = y2 - y1; |
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| 20 | int ax = ABS(dx) << 1; |
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| 21 | int ay = ABS(dy) << 1; |
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| 22 | int sx = (dx >= 0) ? 1 : -1; |
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| 23 | int sy = (dy >= 0) ? 1 : -1; |
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| 24 | |||
| 25 | int x = x1; |
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| 26 | int y = y1; |
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| 27 | |||
| 28 | if (ax > ay) { |
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| 29 | int d = ay - (ax >> 1); |
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| 30 | while (x != x2) { |
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| 31 | vga_drawpixel(x, y); |
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| 32 | |||
| 33 | if (d > 0 || (d == 0 && sx == 1)) { |
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| 34 | y += sy; |
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| 35 | d -= ax; |
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| 36 | } |
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| 37 | x += sx; |
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| 38 | d += ay; |
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| 39 | } |
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| 40 | } else { |
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| 41 | int d = ax - (ay >> 1); |
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| 42 | while (y != y2) { |
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| 43 | vga_drawpixel(x, y); |
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| 44 | |||
| 45 | if (d > 0 || (d == 0 && sy == 1)) { |
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| 46 | x += sx; |
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| 47 | d -= ay; |
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| 48 | } |
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| 49 | y += sy; |
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| 50 | d += ax; |
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| 51 | } |
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| 52 | } |
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| 53 | vga_drawpixel(x, y); |
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| 54 | |||
| 55 | return 0; |
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| 56 | } |
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| 57 |