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/*
!!DESCRIPTION!! equality problem
!!ORIGIN!! Testsuite
!!LICENCE!! Public Domain
*/
/*
Different results, depending on whether constant is on left or right side.
The optimizer sometimes makes code that executes the right-side expression
as eight bits; but then, tests it against the left-side zero as 16 bits.
The high-byte is garbage; therefore, that test might, or might not, work.
It depends on the platform and the amount of optimization.
http://www.cc65.org/mailarchive/2014-10/11680.html
http://www.cc65.org/mailarchive/2014-10/11682.html
http://www.cc65.org/mailarchive/2014-10/11683.html
*/
#include <stdio.h>
static unsigned char fails = 4;
static unsigned char bad[3], good[3];
int main(void)
{
unsigned char joy_state = 0x7e;
unsigned a, b;
/* NOTE: It fails in only the printf() statements, the other stuff
below works! */
printf("bad: %u, ", 0 == (joy_state & 1) );
printf("good: %u\n", (joy_state & 1) == 0 );
sprintf(bad, "%u", 0 == (joy_state & 1) );
sprintf(good, "%u", (joy_state & 1) == 0 );
printf("bad: %u, ", bad[0] - '0' );
printf("good: %u\n", good[0] - '0' );
fails -= bad[0] - '0';
fails -= good[0] - '0';
if (0 == (joy_state & 1)) fails--;
if ((joy_state & 1) == 0) fails--;
printf("failures: %u\n", fails );
/* The above printf() returns a value with a zero high-byte.
** Therefore, the next (broken) statement works (by accident).
*/
a = 0 == (joy_state & 1);
b = (joy_state & 1) == 0;
printf("a: %u, ", a );
printf("b: %u\n", b );
return fails;
}
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