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#include "hexdecode.h"
static int hexdigit(char x) {
if (x >= '0' && x <= '9') return x - '0';
if (x >= 'a' && x <= 'f') return 10 + (x - 'a');
if (x >= 'A' && x <= 'F') return 10 + (x - 'A');
return -1;
}
int hexdecode(unsigned char *y, long long len, const unsigned char *x, long long xlen) {
int digit0;
int digit1;
if (!x) return 0;
while (len > 0 && xlen >= 2) {
digit0 = hexdigit(x[0]); if (digit0 == -1) return 0;
digit1 = hexdigit(x[1]); if (digit1 == -1) return 0;
*y++ = digit1 + 16 * digit0;
--len;
x += 2;
xlen -= 2;
}
if (xlen != 0) return 0;
return 1;
}
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