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#include #include #include #include #define VIDEO_INT 0x10 /* the BIOS video interrupt. */ #define WRITE_DOT 0x0C /* BIOS func to plot a pixel. */ #define SET_MODE 0x00 /* BIOS func to set the video mode. */ #define VGA_256_COLOR_MODE 0x13 /* use to set 256-color mode. */ #define TEXT_MODE 0x03 /* use to set 80x25 text mode. */ #define SCREEN_WIDTH 320 /* width in pixels of mode 0x13 */ #define SCREEN_HEIGHT 200 /* height in pixels of mode 0x13 */ #define NUM_COLORS 256 /* number of colors in mode 0x13 */ typedef unsigned char byte; typedef unsigned short word; byte *VGA = (byte *)0xA0000; /* this points to video memory. */ word *my_clock = (word *)0x046C; /* this points to the 18.2hz system clock. */ /************************************************************************** * set_mode * * Sets the video mode. * **************************************************************************/ void set_mode(byte mode) { union REGS regs; regs.h.ah = SET_MODE; regs.h.al = mode; int86(VIDEO_INT, ®s, ®s); } /************************************************************************** * plot_pixel_slow * * Plot a pixel by using BIOS function 0x0C (Write Dot). * **************************************************************************/ void plot_pixel_slow(int x,int y,byte color) { union REGS regs; regs.h.ah = WRITE_DOT; regs.h.al = color; regs.x.cx = x; regs.x.dx = y; int86(VIDEO_INT, ®s, ®s); } /************************************************************************** * plot_pixel_fast * * Plot a pixel by directly writing to video memory. * **************************************************************************/ void plot_pixel_fast(int x,int y,byte color) { VGA[y*SCREEN_WIDTH+x]=color; } /************************************************************************** * Main * * Plots 50000 pixels two different ways: using the BIOS and by * * directly writing to video memory. * **************************************************************************/ void main() { int x,y,color; float t1,t2; word i,start; if (__djgpp_nearptr_enable() == 0) { printf("Could get access to first 640K of memory.\n"); exit(-1); } VGA+=__djgpp_conventional_base; my_clock = (void *)my_clock + __djgpp_conventional_base; srand(*my_clock); /* seed the number generator. */ set_mode(VGA_256_COLOR_MODE); /* set the video mode. */ start=*my_clock; /* record the starting time. */ for(i=0;i