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