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#include <stdarg.h>
#include <stddef.h>
#include <stdint.h>
#include <stdlib.h>
/* adapted from <http://www.strudel.org.uk/itoa/> */
char* itoa(int val, int base)
{
static char buf[32] = {0};
int neg = 0;
if(val < 0)
{
val = -val;
neg = 1;
}
int i = 30;
do
{
buf[i] = "0123456789abcdef"[val % base];
--i;
val /= base;
}
while(val && i);
if(neg)
{
buf[i] = '-';
}
return &buf[i+(neg?0:1)];
}
static unsigned long rand_s1 = 18, rand_s2 = 5, rand_s3 = 43;
#define M 1103515245UL
#define A 12345UL
/* this is a very fast tausworthe RNG */
unsigned int rand(void)
{
rand_s1 = (((rand_s1&4294967294)<<12)^(((rand_s1<<13)^rand_s1)>>19));
rand_s2 = (((rand_s2&4294967288)<< 4)^(((rand_s2<< 2)^rand_s2)>>25));
rand_s3 = (((rand_s3&4294967280)<<17)^(((rand_s3<< 3)^rand_s3)>>11));
return (rand_s1 ^ rand_s2 ^ rand_s3);
}
void srand(unsigned int seed)
{
if(!seed)
seed = 42;
rand_s1 = seed++;
rand_s2 = seed++;
rand_s3 = seed++;
/* "warm it up" */
for(int i=0;i<10;++i)
rand();
}
int abs(int val)
{
return (val<0?-val:val);
}
void *malloc(size_t sz)
{
static uint8_t mallocbuf[1024*1024*16];
static uint8_t *next_ptr = mallocbuf;
static int bytes_left = sizeof(mallocbuf);
bytes_left -= sz;
if(bytes_left < 0)
return NULL;
else
{
void *ret = next_ptr;
next_ptr += sz;
return ret;
}
}
static inline int snputs(char *buf, int idx, int sz, const char *str)
{
while(idx < sz && *str)
{
buf[idx++] = *str++;
}
return idx;
}
static char hex_table[16] = { '0', '1', '2', '3', '4', '5', '6', '7',
'8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };
static inline int snprint_hex(char *buf, int idx, int sz, unsigned int n)
{
unsigned mask = 0xF0000000;
unsigned shift = 28;
while(mask && idx < sz)
{
buf[idx++] = hex_table[(n & mask) >> shift];
mask >>= 4;
shift -= 4;
}
return idx;
}
int snprintf(char *buf, int sz, const char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
int i = 0;
/* leave room for the null! */
sz--;
while(*fmt && i < sz)
{
char ch = *fmt++;
switch(ch)
{
case '%':
{
switch(*fmt++)
{
case 'c':
buf[i++] = va_arg(ap, int);
break;
case 's':
i = snputs(buf, i, sz, va_arg(ap, const char*));
break;
case 'x':
i = snprint_hex(buf, i, sz, va_arg(ap, unsigned));
break;
case 'd':
i = snputs(buf, i, sz, itoa(va_arg(ap, unsigned), 10));
break;
default:
i = snputs(buf, i, sz, "snprintf: unknown format\n");
break;
}
break;
}
default:
buf[i++] = ch;
break;
}
}
buf[i] = '\0';
va_end(ap);
return 0;
}
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