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/* Derived from CPython 3.7's operator.c::_tscmp
*/
#include <stdlib.h>
#include <wchar.h>
#include "src/precommondefs.h"
#include "tscmp.h"
int
pypy_tscmp(const char *a, const char *b, Signed len_a, Signed len_b)
{
/* The volatile type declarations make sure that the compiler has no
* chance to optimize and fold the code in any way that may change
* the timing.
*/
volatile Signed length;
volatile const char *left;
volatile const char *right;
Signed i;
volatile char result;
/* loop count depends on length of b */
length = len_b;
left = NULL;
right = b;
/* don't use else here to keep the amount of CPU instructions constant,
* volatile forces re-evaluation
* */
if (len_a == length) {
left = *((volatile const char**)&a);
result = 0;
}
if (len_a != length) {
left = b;
result = 1;
}
for (i=0; i < length; i++) {
result |= *left++ ^ *right++;
}
return (result == 0);
}
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