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[/] [openmsp430/] [trunk/] [fpga/] [actel_m1a3pl_dev_kit/] [software/] [spacewar/] [cline.c] - Rev 158
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#include <stdlib.h> #include "spacewar.h" //************************************************************ // externals // extern volatile int xinit, yinit; extern void set_xy(int, int); // ************************************************************ // // cline // // continue line draw // /* Description: Draws short lines based on fixed size increments so longer lines have more points. First calculates the delta x and delta y. Finds the larger. Scales the larger by dividing by 2 until delta is less that fixed_inc. Scales the other increment at the same time. Also generates the loop counter for # of increments to draw the line. Finally the function draws the line with points. */ void cline(int xfin, int yfin) { int delta_x, delta_y, delta_adj; int i = 1; delta_x = (xfin - xinit); delta_y = (yfin - yinit); // find larger delta_x or delta_y - use the larger to scale delta_adj = (abs(delta_y) <= abs(delta_x)) ? abs(delta_x) : abs(delta_y); // calc the delta inc while(fixed_inc < delta_adj) { i += i; ; // double loop counter delta_x = delta_x >> 1; // 1/2 inc size x delta_y = delta_y >> 1; // 1/2 inc size y delta_adj = delta_adj >> 1; } // draw the line with dots while(i--) { set_xy(xinit, yinit); // move dot xinit += delta_x; yinit += delta_y; } }
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