femtolisp/llt/int2str.c

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#include <stdlib.h>
#include "dtypes.h"
char *int2str(char *dest, size_t len, int64_t num, uint32_t base)
{
int i = len-1, neg = 0;
int64_t b = (int64_t)base;
char ch;
if (num < 0) {
num = -num;
neg = 1;
}
dest[i--] = '\0';
while (i >= 0) {
ch = (char)(num % b);
if (ch < 10)
ch += '0';
else
ch = ch-10+'a';
dest[i--] = ch;
num /= b;
if (num == 0)
break;
}
if (i >= 0 && neg)
dest[i--] = '-';
return &dest[i+1];
}
int isdigit_base(char c, int base)
{
if (base < 11)
return (c >= '0' && c < '0'+base);
return ((c >= '0' && c <= '9') ||
(c >= 'a' && c < 'a'+base-10) ||
(c >= 'A' && c < 'A'+base-10));
}
/* assumes valid base, returns 1 on error, 0 if OK */
int str2int(char *str, size_t len, int64_t *res, uint32_t base)
{
int64_t result, place;
char digit;
int i;
place = 1; result = 0;
for(i=len-1; i>=0; i--) {
digit = str[i];
if (!isdigit_base(digit, base))
return 1;
if (digit <= '9')
digit -= '0';
else if (digit >= 'a')
digit = digit-'a'+10;
else if (digit >= 'A')
digit = digit-'A'+10;
result += digit * place;
place *= base;
}
*res = result;
return 0;
}