| 1 | /* |
| 2 | * Test R5900-specific DIV1. |
| 3 | */ |
| 4 | |
| 5 | #include <stdio.h> |
| 6 | #include <inttypes.h> |
| 7 | #include <assert.h> |
| 8 | |
| 9 | struct quotient_remainder { int32_t quotient, remainder; }; |
| 10 | |
| 11 | static 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 | |
| 28 | static 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 | |
| 38 | static 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 | |
| 48 | int 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 | } |