LXR qemu/tests/tcg/mips/user/isa/r5900/test_r5900

   1/*
   2 * Test R5900-specific DIV1.
   3 */
   4
   5#include <stdio.h>
   6#include <inttypes.h>
   7#include <assert.h>
   8
   9struct quotient_remainder { int32_t quotient, remainder; };
  10
  11static struct quotient_remainder div1(int32_t rs, int32_t rt)
  12{
  13    int32_t lo, hi;
  14
  15    __asm__ __volatile__ (
  16            "    div1 $0, %2, %3\n"
  17            "    mflo1 %0\n"
  18            "    mfhi1 %1\n"
  19            : "=r" (lo), "=r" (hi)
  20            : "r" (rs), "r" (rt));
  21
  22    assert(rs / rt == lo);
  23    assert(rs % rt == hi);
  24
  25    return (struct quotient_remainder) { .quotient = lo, .remainder = hi };
  26}
  27
  28static void verify_div1(int32_t rs, int32_t rt,
  29                        int32_t expected_quotient,
  30                        int32_t expected_remainder)
  31{
  32    struct quotient_remainder qr = div1(rs, rt);
  33
  34    assert(qr.quotient == expected_quotient);
  35    assert(qr.remainder == expected_remainder);
  36}
  37
  38static void verify_div1_negations(int32_t rs, int32_t rt,
  39                                  int32_t expected_quotient,
  40                                  int32_t expected_remainder)
  41{
  42    verify_div1(rs, rt, expected_quotient, expected_remainder);
  43    verify_div1(rs, -rt, -expected_quotient, expected_remainder);
  44    verify_div1(-rs, rt, -expected_quotient, -expected_remainder);
  45    verify_div1(-rs, -rt, expected_quotient, -expected_remainder);
  46}
  47
  48int main()
  49{
  50    verify_div1_negations(0, 1, 0, 0);
  51    verify_div1_negations(1, 1, 1, 0);
  52    verify_div1_negations(1, 2, 0, 1);
  53    verify_div1_negations(17, 19, 0, 17);
  54    verify_div1_negations(19, 17, 1, 2);
  55    verify_div1_negations(77773, 101, 770, 3);
  56
  57    verify_div1(-0x80000000,  1, -0x80000000, 0);
  58
  59    /*
  60     * Supplementary explanation from the Toshiba TX System RISC TX79 Core
  61     * Architecture manual, A-38 and B-7, https://wiki.qemu.org/File:C790.pdf
  62     *
  63     * Normally, when 0x80000000 (-2147483648) the signed minimum value is
  64     * divided by 0xFFFFFFFF (-1), the operation will result in an overflow.
  65     * However, in this instruction an overflow exception doesn't occur and
  66     * the result will be as follows:
  67     *
  68     * Quotient is 0x80000000 (-2147483648), and remainder is 0x00000000 (0).
  69     */
  70    verify_div1(-0x80000000, -1, -0x80000000, 0);
  71
  72    return 0;
  73}
  74