test_r5900_div1.c (2226B)
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 }