added amorphous pressure ~1/r^2

[physik/morpheus.git] / random.c

diff --git a/random.c b/random.c
index 73e69f5..51b310b 100644 (file)
--- a/random.c
+++ b/random.c
@@ -5,23 +5,38 @@
 
 #include <stdio.h>
 #include <stdlib.h>
+#include <unistd.h>
+
 #include "defines.h"
 
-extern int sum_z_segments;
+/* global and extern variables */
+extern u32 sum_z_cells;
+extern int random_fd;
 
-/* return random integer between 0 - max */
-int rand_get(int max) {
- return((int) (rand() * (max*1.0/RAND_MAX)) );
+/* return random integer between 0 - max-1 */
+u32 rand_get(u32 max) 
+{
+ u32 rand_int;
+ if(read(random_fd,&rand_int,4)!=4)
+ {
+  puts("failed reading 4 bytes of random data");
+  return -23;
+ }
+ /* cells numbered 0...max-1 */
+ return((u32)(rand_int*(max*1.0/URAND_MAX)));
 }
 
 /* get z value (linear growth of probability with depths) */
-int rand_get_lgp(int slope_cc,int start_cc) {
- int z,i;
- z=rand_get(sum_z_segments);
- for(i=0;;i++) {
-  z-=i*slope_cc;
+u32 rand_get_lgp(int slope_nel,int start_nel)
+{
+ int z;
+ u32 i;
+ z=rand_get(sum_z_cells)+1; /* +1 as rand_get returns values 0...max-1 */
+ for(i=1;;i++) {
+  z-=(start_nel+i*slope_nel);
   if(z<=0) break;
  }
- return i;
+ return(i-1); /* return values 0...z_cell-1 */
 }
 
+