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Make trasher use a well defined random number generator and allow the seed to be specified on the cmd line.

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Originally committed as revision 22228 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Michael Niedermayer 2010-03-06 01:31:17 +00:00
parent 814c56413d
commit 47cf98efcb
1 changed files with 11 additions and 7 deletions
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18
tools/trasher.c
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@ -24,13 +24,18 @@
#include <time.h> #include <time.h>
#include <inttypes.h> #include <inttypes.h>
static uint32_t state;
static uint32_t ran(void){
return state= state*1664525+1013904223;
}
int main(int argc, char** argv) int main(int argc, char** argv)
{ {
FILE *f; FILE *f;
int count, maxburst, length; int count, maxburst, length;
if (argc < 4){ if (argc < 5){
printf("USAGE: trasher <filename> <count> <maxburst>\n"); printf("USAGE: trasher <filename> <count> <maxburst> <seed>\n");
return 1; return 1;
} }
@ -41,16 +46,15 @@ int main(int argc, char** argv)
} }
count= atoi(argv[2]); count= atoi(argv[2]);
maxburst= atoi(argv[3]); maxburst= atoi(argv[3]);
state= atoi(argv[4]);
srandom (time (0));
fseek(f, 0, SEEK_END); fseek(f, 0, SEEK_END);
length= ftell(f); length= ftell(f);
fseek(f, 0, SEEK_SET); fseek(f, 0, SEEK_SET);
while(count--){ while(count--){
int burst= 1 + random() * (uint64_t) (abs(maxburst)-1) / RAND_MAX; int burst= 1 + ran() * (uint64_t) (abs(maxburst)-1) / UINT32_MAX;
int pos= random() * (uint64_t) length / RAND_MAX; int pos= ran() * (uint64_t) length / UINT32_MAX;
fseek(f, pos, SEEK_SET); fseek(f, pos, SEEK_SET);
if(maxburst<0) burst= -maxburst; if(maxburst<0) burst= -maxburst;
@ -59,7 +63,7 @@ int main(int argc, char** argv)
continue; continue;
while(burst--){ while(burst--){
int val= random() * 256ULL / RAND_MAX; int val= ran() * 256ULL / UINT32_MAX;
if(maxburst<0) val=0; if(maxburst<0) val=0;