3.73 Find Range I

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Write a function in assembly code that matches the behavior of the function find_range in Figure 3.51. Your code should contain only one floating-point comparison instruction. Test your code on all 2^32 possible argument written assembly code into C programs.

Code:

#include <stdio.h>
#include <assert.h>

typedef enum {NEG, ZERO, POS, OTHER} range_t;

range_t find_range(float x) {
  __asm__(
      "vxorps %xmm1, %xmm1, %xmm1\n\t"
      "vucomiss %xmm1, %xmm0\n\t"
      "jp .P\n\t"
      "ja .A\n\t"
      "jb .B\n\t"
      "je .E\n\t"
      ".A:\n\t"
      "movl $2, %eax\n\t"
      "jmp .Done\n\t"
      ".B:\n\t"
      "movl $0, %eax\n\t"
      "jmp .Done\n\t"
      ".E:\n\t"
      "movl $1, %eax\n\t"
      "jmp .Done\n\t"
      ".P:\n\t"
      "movl $3, %eax\n\t"
      ".Done:\n\t"
      );
}

int main(int argc, char* argv[]) {
    range_t n = NEG, z = ZERO, p = POS, o = OTHER;
    assert(o == find_range(0.0/0.0));
    assert(n == find_range(-2.3));
    assert(z == find_range(0.0));
    assert(p == find_range(3.33));
    return 0;
}