Problem - Kevin Tafuro

init_rand(a, b);
return 0;
}
12.8 Disguising Boolean Values
Problem
Variables representing boolean values are difficult to disguise because they usually
compile to comparisons with 0 or 1.
Solution
Disguising boolean values can be tackled effectively at the assembly-language level
by replacing simple test-and-branch code with more complex branching (see Recipe
12.3). Alternatively, the default boolean test can be replaced with an addition.
Discussion
By replacing the default boolean test—usually a sub or an and instruction—with an
addition, the purpose of the variable becomes unclear. Rather than implying a yes or
no decision, the variable appears to represent two related values:
typedef struct {
char x;
char y;
} spc_bool_t;
#define SPC_TEST_BOOL(b) ((b).x + (b).y)
#define SPC_SET_BOOL_TRUE(b) do { (b).x = 1; (b).y = 0; } while (0)
#define SPC_SET_BOOL_FALSE(b) do { (b).x = -10; (b).y = 10; } while (0)
The SPC_TEST_BOOL macro can be used in conditional expressions:
spc_bool_t b;
SPC_SET_BOOL_TRUE(b);
if (SPC_TEST_BOOL(b)) printf("true!\n");
else printf("false!\n");
See Also
Recipe 12.3
670 | Chapter 12: Anti-Tampering
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