这是一个本人学习 csapp 的 learning 库
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118 regels
1.7 KiB

/* Testing Code */
#include <limits.h>
#include <math.h>
/* Routines used by floation point test code */
/* Convert from bit level representation to floating point number */
float u2f(unsigned u) {
union {
unsigned u;
float f;
} a;
a.u = u;
return a.f;
}
/* Convert from floating point number to bit-level representation */
unsigned f2u(float f) {
union {
unsigned u;
float f;
} a;
a.f = f;
return a.u;
}
//1
int test_bitXor(int x, int y)
{
return x^y;
}
int test_tmin(void) {
return 0x80000000;
}
//2
int test_isTmax(int x) {
return x == 0x7FFFFFFF;
}
int test_allOddBits(int x) {
int i;
for (i = 1; i < 32; i+=2)
if ((x & (1<<i)) == 0)
return 0;
return 1;
}
int test_negate(int x) {
return -x;
}
//3
int test_isAsciiDigit(int x) {
return (0x30 <= x) && (x <= 0x39);
}
int test_conditional(int x, int y, int z)
{
return x?y:z;
}
int test_isLessOrEqual(int x, int y)
{
return x <= y;
}
//4
int test_logicalNeg(int x)
{
return !x;
}
int test_howManyBits(int x) {
unsigned int a, cnt;
x = x<0 ? -x-1 : x;
a = (unsigned int)x;
for (cnt=0; a; a>>=1, cnt++)
;
return (int)(cnt + 1);
}
//float
unsigned test_floatScale2(unsigned uf) {
float f = u2f(uf);
float tf = 2*f;
if (isnan(f))
return uf;
else
return f2u(tf);
}
int test_floatFloat2Int(unsigned uf) {
float f = u2f(uf);
int x = (int) f;
return x;
}
unsigned test_floatPower2(int x) {
float result = 1.0;
float p2 = 2.0;
int recip = (x < 0);
/* treat tmin specially */
if ((unsigned)x == 0x80000000) {
return 0;
}
if (recip) {
x = -x;
p2 = 0.5;
}
while (x > 0) {
if (x & 0x1)
result = result * p2;
p2 = p2 * p2;
x >>= 1;
}
return f2u(result);
}