/*# proc: bres_line_alloc - same as bres_line except if nalloc == 0 allocates new# proc:                   memory, or reallocs if nalloc is too small.*/#include <stdio.h>#include <math.h>#include <defs.h>/***************************************************************************//* At call nalloc is how much memory is currently allocated for x_list and *//* y_list.  If nalloc == 0 routine will allocate needed memory based on:   *//*                                                                         *//*         asize = max(abs(x2-x1)+2,abs(y2-y1)+2))                         *//*                                                                         *//* If nalloc < asize will realloc memory for x_list and y_list to asize.   *//***************************************************************************/bres_line_alloc(x1,y1,x2,y2,x_list,y_list,num,nalloc)int x1,y1,x2,y2,**x_list,**y_list,*num,*nalloc;{   int x, y, i, sign;   int dx, dy, dy2, dx2, dymdx2;   int x_end, y_end;   int x_incr, y_incr;   int p;   int *xptr, *yptr;   int asize;   asize = max(abs(x2-x1)+2, abs(y2-y1)+2);   if(*nalloc == 0) {      *nalloc = asize;      malloc_int(x_list, *nalloc, "bres_line_alloc x_list");      malloc_int(y_list, *nalloc, "bres_line_alloc y_list");   }   else if(*nalloc < asize) {      *nalloc = asize;      realloc_int(x_list, *nalloc, "bres_line_alloc x_list");      realloc_int(y_list, *nalloc, "bres_line_alloc y_list");   }   i = 0;   dx = abs(x1 - x2);   dy = abs(y1 - y2);   dx2 = dx<<1;   dy2 = dy<<1;   dymdx2 = (dy - dx)<<1;   p = dy2 - dx;   xptr = *x_list;   yptr = *y_list;   if(dx == 0){      x = x1;      y = y1;      y_end = y2;      xptr[i] = x;      yptr[i++] = y;      if(y1 > y2){         while(y > y_end){            xptr[i] = x;            yptr[i++] = --y;         }      }      else{         while(y < y_end){            xptr[i] = x;            yptr[i++] = ++y;         }      }      *num = i;      return;   }   if(dy == 0){      x = x1;      y = y1;      x_end = x2;      xptr[i] = x;      yptr[i++] = y;      if(x1 > x2){         while(x > x_end){            xptr[i] = --x;            yptr[i++] = y;         }      }      else{         while(x < x_end){            xptr[i] = ++x;            yptr[i++] = y;         }      }      *num = i;      return;   }   if(dx > dy){      if(y1 < y2)         y_incr = 1;      else         y_incr = -1;      x = x1;      y = y1;      x_end = x2;      xptr[i] = x;      yptr[i++] = y;      if(x1 <= x2) {         while(x < x_end){            ++x;            if(p < 0)               p = p + dy2;            else{               y += y_incr;               p = p + dymdx2;            }            xptr[i] = x;            yptr[i++] = y;         }         if(x != x2 || y != y2) {            xptr[i] = x2;            yptr[i++] = y2;         }      }      else {         while(x > x_end){            --x;            if(p < 0)               p = p + dy2;            else{               y += y_incr;               p = p + dymdx2;            }            xptr[i] = x;            yptr[i++] = y;         }         if(x != x2 || y != y2) {            xptr[i] = x2;            yptr[i++] = y2;         }      }      *num = i;      return;   }   else {      if(x1 < x2)         x_incr = 1;      else         x_incr = -1;      x = x1;      y = y1;      y_end = y2;      xptr[i] = x;      yptr[i++] = y;      if(y1 <= y2) {         while(y < y_end){            ++y;            if(p > 0)               p = p - dx2;            else{               x += x_incr;               p = p + dymdx2;            }            xptr[i] = x;            yptr[i++] = y;         }         if(x != x2 || y != y2) {            xptr[i] = x2;            yptr[i++] = y2;         }      }      else {         while(y > y_end){            --y;            if(p > 0)               p = p - dx2;            else{               x += x_incr;               p = p + dymdx2;            }            xptr[i] = x;            yptr[i++] = y;         }         if(x != x2 || y != y2) {            xptr[i] = x2;            yptr[i++] = y2;         }      }      *num = i;      return;   }}