--

[physik/morpheus.git] / random.c

diff --git a/random.c b/random.c
index 73e69f5..81a0667 100644 (file)
--- a/random.c
+++ b/random.c
@@ -5,23 +5,56 @@
 
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <unistd.h>
+
 #include "defines.h"
 
-extern int sum_z_segments;
+/* global and extern variables */
+extern u32 gr;
+extern int random_fd;
+extern u32 *rand_buf,*rand_current;
+extern char random_file[MAX_CHARS_RANDOM_FILE];
 
-/* 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) 
+{
+ if(rand_current>=rand_buf+(RAND_BUF_SIZE/sizeof(u32)))
+ {
+  printfd("debug: reading new random bytes\n");
+  if(read(random_fd,rand_buf,RAND_BUF_SIZE)!=RAND_BUF_SIZE)
+  {
+   if(strcmp(random_file,""))
+   {
+    puts("random file end, starting over ...");
+    lseek(random_fd,0,SEEK_SET);
+   } else
+   {
+    puts("failed reading 1 mega bytes of random data");
+    return -23;
+   }
+  }
+  printfd("debug: finished reading random bytes\n");
+  rand_current=rand_buf;
+ }
+ /* cells numbered 0...max-1 */
+ return((u32)(*(rand_current++)*(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,int start,u32 z_max)
+{
+ int z;
+ u32 i,weighted_sum_z;
+ weighted_sum_z=z_max*start+slope*gr;
+ z=rand_get(weighted_sum_z)+1; /* +1 as rand_get returns values 0...max-1 */
+ for(i=1;;i++)
+ {
+  z-=(start+i*slope);
   if(z<=0) break;
  }
- return i;
+ return(i-1); /* return values 0...z_cell-1 */
 }