[PULL 11/23] qemu/int128: add int128_urshift

[Daniel Henrique Barboza]

From: Matheus Ferst <matheus.ferst@eldorado.org.br>

Implement an unsigned right shift for Int128 values and add the same
tests cases of int128_rshift in the unit test.

Signed-off-by: Matheus Ferst <matheus.ferst@eldorado.org.br>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20220330175932.6995-3-matheus.ferst@eldorado.org.br>
[danielhb: fixed long lines in test_urshift()]
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
---
 include/qemu/int128.h    | 19 +++++++++++++++
 tests/unit/test-int128.c | 50 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 69 insertions(+)

diff --git a/include/qemu/int128.h b/include/qemu/int128.h
index 37e07fd6dd..1f82918c73 100644
--- a/include/qemu/int128.h
+++ b/include/qemu/int128.h
@@ -83,6 +83,11 @@ static inline Int128 int128_rshift(Int128 a, int n)
     return a >> n;
 }
 
+static inline Int128 int128_urshift(Int128 a, int n)
+{
+    return (__uint128_t)a >> n;
+}
+
 static inline Int128 int128_lshift(Int128 a, int n)
 {
     return a << n;
@@ -299,6 +304,20 @@ static inline Int128 int128_rshift(Int128 a, int n)
     }
 }
 
+static inline Int128 int128_urshift(Int128 a, int n)
+{
+    uint64_t h = a.hi;
+    if (!n) {
+        return a;
+    }
+    h = h >> (n & 63);
+    if (n >= 64) {
+        return int128_make64(h);
+    } else {
+        return int128_make128((a.lo >> n) | ((uint64_t)a.hi << (64 - n)), h);
+    }
+}
+
 static inline Int128 int128_lshift(Int128 a, int n)
 {
     uint64_t l = a.lo << (n & 63);
diff --git a/tests/unit/test-int128.c b/tests/unit/test-int128.c
index b86a3c76e6..25db2455e8 100644
--- a/tests/unit/test-int128.c
+++ b/tests/unit/test-int128.c
@@ -206,6 +206,55 @@ static void test_rshift(void)
     test_rshift_one(0xFFFE8000U,  0, 0xFFFFFFFFFFFFFFFEULL, 
0x8000000000000000ULL);
 }
 
+static void __attribute__((__noinline__)) ATTRIBUTE_NOCLONE
+test_urshift_one(uint32_t x, int n, uint64_t h, uint64_t l)
+{
+    Int128 a = expand(x);
+    Int128 r = int128_urshift(a, n);
+    g_assert_cmpuint(int128_getlo(r), ==, l);
+    g_assert_cmpuint(int128_gethi(r), ==, h);
+}
+
+static void test_urshift(void)
+{
+    test_urshift_one(0x00010000U, 64, 0x0000000000000000ULL,
+                     0x0000000000000001ULL);
+    test_urshift_one(0x80010000U, 64, 0x0000000000000000ULL,
+                     0x8000000000000001ULL);
+    test_urshift_one(0x7FFE0000U, 64, 0x0000000000000000ULL,
+                     0x7FFFFFFFFFFFFFFEULL);
+    test_urshift_one(0xFFFE0000U, 64, 0x0000000000000000ULL,
+                     0xFFFFFFFFFFFFFFFEULL);
+    test_urshift_one(0x00010000U, 60, 0x0000000000000000ULL,
+                     0x0000000000000010ULL);
+    test_urshift_one(0x80010000U, 60, 0x0000000000000008ULL,
+                     0x0000000000000010ULL);
+    test_urshift_one(0x00018000U, 60, 0x0000000000000000ULL,
+                     0x0000000000000018ULL);
+    test_urshift_one(0x80018000U, 60, 0x0000000000000008ULL,
+                     0x0000000000000018ULL);
+    test_urshift_one(0x7FFE0000U, 60, 0x0000000000000007ULL,
+                     0xFFFFFFFFFFFFFFE0ULL);
+    test_urshift_one(0xFFFE0000U, 60, 0x000000000000000FULL,
+                     0xFFFFFFFFFFFFFFE0ULL);
+    test_urshift_one(0x7FFE8000U, 60, 0x0000000000000007ULL,
+                     0xFFFFFFFFFFFFFFE8ULL);
+    test_urshift_one(0xFFFE8000U, 60, 0x000000000000000FULL,
+                     0xFFFFFFFFFFFFFFE8ULL);
+    test_urshift_one(0x00018000U,  0, 0x0000000000000001ULL,
+                     0x8000000000000000ULL);
+    test_urshift_one(0x80018000U,  0, 0x8000000000000001ULL,
+                     0x8000000000000000ULL);
+    test_urshift_one(0x7FFE0000U,  0, 0x7FFFFFFFFFFFFFFEULL,
+                     0x0000000000000000ULL);
+    test_urshift_one(0xFFFE0000U,  0, 0xFFFFFFFFFFFFFFFEULL,
+                     0x0000000000000000ULL);
+    test_urshift_one(0x7FFE8000U,  0, 0x7FFFFFFFFFFFFFFEULL,
+                     0x8000000000000000ULL);
+    test_urshift_one(0xFFFE8000U,  0, 0xFFFFFFFFFFFFFFFEULL,
+                     0x8000000000000000ULL);
+}
+
 int main(int argc, char **argv)
 {
     g_test_init(&argc, &argv, NULL);
@@ -219,5 +268,6 @@ int main(int argc, char **argv)
     g_test_add_func("/int128/int128_ge", test_ge);
     g_test_add_func("/int128/int128_gt", test_gt);
     g_test_add_func("/int128/int128_rshift", test_rshift);
+    g_test_add_func("/int128/int128_urshift", test_urshift);
     return g_test_run();
 }
-- 
2.35.1