tests/tcg/mips: Add tests for R5900 DIV1

Add a test for DIV1.

Reviewed-by: Aleksandar Markovic <amarkovic@wavecomp.com>
Signed-off-by: Fredrik Noring <noring@nocrew.org>
Signed-off-by: Aleksandar Markovic <amarkovic@wavecomp.com>

tests/tcg/mips/mipsr5900/Makefile

@@ -8,7 +8,8 @@ SIM_FLAGS=-cpu R5900
 CC      = $(CROSS)gcc
 CFLAGS  = -Wall -mabi=32 -march=r5900 -static
 
-TESTCASES = mflohi1.tst
+TESTCASES = div1.tst
+TESTCASES += mflohi1.tst
 TESTCASES += mtlohi1.tst
 TESTCASES += mult.tst
 TESTCASES += multu.tst

tests/tcg/mips/mipsr5900/div1.c

@@ -0,0 +1,73 @@
+/*
+ * 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;
+}