117 lines
2.0 KiB
C
117 lines
2.0 KiB
C
#include <internals/display.h>
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#include <display.h>
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#define sgn(x) ((x) < 0 ? -1 : 1)
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#define abs(x) ((x) < 0 ? -(x) : (x))
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#define rnd(x) ((int)((x) + 0.5))
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/*
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dline()
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Draws a line on the screen. Automatically optimizes horizontal and
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vertical lines.
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*/
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static void dhline(int x1, int x2, int y, enum Color color)
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{
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uint32_t masks[4];
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int offset = y << 2;
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int i;
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// Swapping x1 and x2 if needed.
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if(x1 > x2) x1 ^= x2, x2 ^= x1, x1 ^= x2;
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getMasks(x1, x2, masks);
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switch(color)
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{
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case Color_White:
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for(i = 0; i < 4; i++) vram[offset + i] &= ~masks[i];
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break;
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case Color_Black:
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for(i = 0; i < 4; i++) vram[offset + i] |= masks[i];
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break;
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case Color_Invert:
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for(i = 0; i < 4; i++) vram[offset + i] ^= masks[i];
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break;
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default:
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break;
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}
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}
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static void dvline(int y1, int y2, int x, enum Color color)
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{
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int offset = (y1 << 2) + (x >> 5);
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int end = (y2 << 2) + (x >> 5);
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int mask = 0x80000000 >> (x & 31);
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switch(color)
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{
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case Color_White:
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while(offset <= end) vram[offset] &= ~mask, offset += 4;
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break;
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case Color_Black:
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while(offset <= end) vram[offset] |= mask, offset += 4;
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break;
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case Color_Invert:
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while(offset <= end) vram[offset] ^= mask, offset += 4;
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break;
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default:
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break;
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}
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}
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void dline(int x1, int y1, int x2, int y2, enum Color color)
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{
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adjustRectangle(&x1, &y1, &x2, &y2);
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// Possible optimizations.
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if(y1 == y2)
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{
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dhline(x1, x2, y1, color);
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return;
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}
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if(x1 == x2)
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{
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dvline(y1, y2, x1, color);
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return;
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}
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int i, x = x1, y = y1, cumul;
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int dx = x2 - x1, dy = y2 - y1;
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int sx = sgn(dx), sy = sgn(dy);
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dx = abs(dx), dy = abs(dy);
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dpixel(x1, y1, color);
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if(dx >= dy)
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{
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cumul = dx >> 1;
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for(i = 1; i < dx; i++)
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{
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x += sx;
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cumul += dy;
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if(cumul > dx) cumul -= dx, y += sy;
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dpixel(x, y, color);
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}
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}
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else
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{
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cumul = dy >> 1;
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for(i = 1; i < dy; i++)
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{
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y += sy;
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cumul += dx;
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if(cumul > dy) cumul -= dy, x += sx;
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dpixel(x, y, color);
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}
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}
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dpixel(x2, y2, color);
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}
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