diff --git a/include/qemu/int128.h b/include/qemu/int128.h index bfe7678a04..9ed47aafd3 100644 --- a/include/qemu/int128.h +++ b/include/qemu/int128.h @@ -1,6 +1,10 @@ #ifndef INT128_H #define INT128_H +#include +#include +#include + typedef struct Int128 Int128; struct Int128 { @@ -55,21 +59,26 @@ static inline Int128 int128_rshift(Int128 a, int n) static inline Int128 int128_add(Int128 a, Int128 b) { - Int128 r = { a.lo + b.lo, a.hi + b.hi }; - r.hi += (r.lo < a.lo) || (r.lo < b.lo); - return r; + uint64_t lo = a.lo + b.lo; + + /* a.lo <= a.lo + b.lo < a.lo + k (k is the base, 2^64). Hence, + * a.lo + b.lo >= k implies 0 <= lo = a.lo + b.lo - k < a.lo. + * Similarly, a.lo + b.lo < k implies a.lo <= lo = a.lo + b.lo < k. + * + * So the carry is lo < a.lo. + */ + return (Int128) { lo, (uint64_t)a.hi + b.hi + (lo < a.lo) }; } static inline Int128 int128_neg(Int128 a) { - a.lo = ~a.lo; - a.hi = ~a.hi; - return int128_add(a, int128_one()); + uint64_t lo = -a.lo; + return (Int128) { lo, ~(uint64_t)a.hi + !lo }; } static inline Int128 int128_sub(Int128 a, Int128 b) { - return int128_add(a, int128_neg(b)); + return (Int128){ a.lo - b.lo, a.hi - b.hi - (a.lo < b.lo) }; } static inline bool int128_nonneg(Int128 a) @@ -89,7 +98,7 @@ static inline bool int128_ne(Int128 a, Int128 b) static inline bool int128_ge(Int128 a, Int128 b) { - return int128_nonneg(int128_sub(a, b)); + return a.hi > b.hi || (a.hi == b.hi && a.lo >= b.lo); } static inline bool int128_lt(Int128 a, Int128 b) diff --git a/tests/Makefile b/tests/Makefile index c107489f44..279d5f8307 100644 --- a/tests/Makefile +++ b/tests/Makefile @@ -44,6 +44,9 @@ check-unit-y += tests/test-cutils$(EXESUF) gcov-files-test-cutils-y += util/cutils.c check-unit-y += tests/test-mul64$(EXESUF) gcov-files-test-mul64-y = util/host-utils.c +check-unit-y += tests/test-int128$(EXESUF) +# all code tested by test-int128 is inside int128.h +gcov-files-test-int128-y = check-block-$(CONFIG_POSIX) += tests/qemu-iotests-quick.sh @@ -75,7 +78,7 @@ test-obj-y = tests/check-qint.o tests/check-qstring.o tests/check-qdict.o \ tests/test-string-input-visitor.o tests/test-qmp-output-visitor.o \ tests/test-qmp-input-visitor.o tests/test-qmp-input-strict.o \ tests/test-qmp-commands.o tests/test-visitor-serialization.o \ - tests/test-x86-cpuid.o tests/test-mul64.o + tests/test-x86-cpuid.o tests/test-mul64.o tests/test-int128.o test-qapi-obj-y = tests/test-qapi-visit.o tests/test-qapi-types.o @@ -98,6 +101,7 @@ tests/test-hbitmap$(EXESUF): tests/test-hbitmap.o libqemuutil.a libqemustub.a tests/test-x86-cpuid$(EXESUF): tests/test-x86-cpuid.o tests/test-xbzrle$(EXESUF): tests/test-xbzrle.o xbzrle.o page_cache.o libqemuutil.a tests/test-cutils$(EXESUF): tests/test-cutils.o util/cutils.o +tests/test-int128$(EXESUF): tests/test-int128.o tests/test-qapi-types.c tests/test-qapi-types.h :\ $(SRC_PATH)/qapi-schema-test.json $(SRC_PATH)/scripts/qapi-types.py diff --git a/tests/test-int128.c b/tests/test-int128.c new file mode 100644 index 0000000000..5aca032e0c --- /dev/null +++ b/tests/test-int128.c @@ -0,0 +1,212 @@ +/* + * Test Int128 arithmetic + * + * This work is licensed under the terms of the GNU LGPL, version 2 or later. + * See the COPYING.LIB file in the top-level directory. + * + */ + +#include +#include +#include "qemu/int128.h" +#include "qemu/osdep.h" + +static uint32_t tests[8] = { + 0x00000000, 0x00000001, 0x7FFFFFFE, 0x7FFFFFFF, + 0x80000000, 0x80000001, 0xFFFFFFFE, 0xFFFFFFFF, +}; + +#define LOW 3ULL +#define HIGH (1ULL << 63) +#define MIDDLE (-1ULL & ~LOW & ~HIGH) + +static uint64_t expand16(unsigned x) +{ + return (x & LOW) | ((x & 4) ? MIDDLE : 0) | (x & 0x8000 ? HIGH : 0); +} + +static Int128 expand(uint32_t x) +{ + uint64_t l, h; + l = expand16(x & 65535); + h = expand16(x >> 16); + return (Int128) {l, h}; +}; + +static void test_and(void) +{ + int i, j; + + for (i = 0; i < ARRAY_SIZE(tests); ++i) { + for (j = 0; j < ARRAY_SIZE(tests); ++j) { + Int128 a = expand(tests[i]); + Int128 b = expand(tests[j]); + Int128 r = expand(tests[i] & tests[j]); + Int128 s = int128_and(a, b); + g_assert_cmpuint(r.lo, ==, s.lo); + g_assert_cmpuint(r.hi, ==, s.hi); + } + } +} + +static void test_add(void) +{ + int i, j; + + for (i = 0; i < ARRAY_SIZE(tests); ++i) { + for (j = 0; j < ARRAY_SIZE(tests); ++j) { + Int128 a = expand(tests[i]); + Int128 b = expand(tests[j]); + Int128 r = expand(tests[i] + tests[j]); + Int128 s = int128_add(a, b); + g_assert_cmpuint(r.lo, ==, s.lo); + g_assert_cmpuint(r.hi, ==, s.hi); + } + } +} + +static void test_sub(void) +{ + int i, j; + + for (i = 0; i < ARRAY_SIZE(tests); ++i) { + for (j = 0; j < ARRAY_SIZE(tests); ++j) { + Int128 a = expand(tests[i]); + Int128 b = expand(tests[j]); + Int128 r = expand(tests[i] - tests[j]); + Int128 s = int128_sub(a, b); + g_assert_cmpuint(r.lo, ==, s.lo); + g_assert_cmpuint(r.hi, ==, s.hi); + } + } +} + +static void test_neg(void) +{ + int i; + + for (i = 0; i < ARRAY_SIZE(tests); ++i) { + Int128 a = expand(tests[i]); + Int128 r = expand(-tests[i]); + Int128 s = int128_neg(a); + g_assert_cmpuint(r.lo, ==, s.lo); + g_assert_cmpuint(r.hi, ==, s.hi); + } +} + +static void test_nz(void) +{ + int i, j; + + for (i = 0; i < ARRAY_SIZE(tests); ++i) { + for (j = 0; j < ARRAY_SIZE(tests); ++j) { + Int128 a = expand(tests[i]); + g_assert_cmpuint(int128_nz(a), ==, tests[i] != 0); + } + } +} + +static void test_le(void) +{ + int i, j; + + for (i = 0; i < ARRAY_SIZE(tests); ++i) { + for (j = 0; j < ARRAY_SIZE(tests); ++j) { + /* Signed comparison */ + int32_t a = (int32_t) tests[i]; + int32_t b = (int32_t) tests[j]; + g_assert_cmpuint(int128_le(expand(a), expand(b)), ==, a <= b); + } + } +} + +static void test_lt(void) +{ + int i, j; + + for (i = 0; i < ARRAY_SIZE(tests); ++i) { + for (j = 0; j < ARRAY_SIZE(tests); ++j) { + /* Signed comparison */ + int32_t a = (int32_t) tests[i]; + int32_t b = (int32_t) tests[j]; + g_assert_cmpuint(int128_lt(expand(a), expand(b)), ==, a < b); + } + } +} + +static void test_ge(void) +{ + int i, j; + + for (i = 0; i < ARRAY_SIZE(tests); ++i) { + for (j = 0; j < ARRAY_SIZE(tests); ++j) { + /* Signed comparison */ + int32_t a = (int32_t) tests[i]; + int32_t b = (int32_t) tests[j]; + g_assert_cmpuint(int128_ge(expand(a), expand(b)), ==, a >= b); + } + } +} + +static void test_gt(void) +{ + int i, j; + + for (i = 0; i < ARRAY_SIZE(tests); ++i) { + for (j = 0; j < ARRAY_SIZE(tests); ++j) { + /* Signed comparison */ + int32_t a = (int32_t) tests[i]; + int32_t b = (int32_t) tests[j]; + g_assert_cmpuint(int128_gt(expand(a), expand(b)), ==, a > b); + } + } +} + +/* Make sure to test undefined behavior at runtime! */ + +static void __attribute__((__noinline__, __noclone__)) +test_rshift_one(uint32_t x, int n, uint64_t h, uint64_t l) +{ + Int128 a = expand(x); + Int128 r = int128_rshift(a, n); + g_assert_cmpuint(r.lo, ==, l); + g_assert_cmpuint(r.hi, ==, h); +} + +static void test_rshift(void) +{ + test_rshift_one(0x00010000U, 64, 0x0000000000000000ULL, 0x0000000000000001ULL); + test_rshift_one(0x80010000U, 64, 0xFFFFFFFFFFFFFFFFULL, 0x8000000000000001ULL); + test_rshift_one(0x7FFE0000U, 64, 0x0000000000000000ULL, 0x7FFFFFFFFFFFFFFEULL); + test_rshift_one(0xFFFE0000U, 64, 0xFFFFFFFFFFFFFFFFULL, 0xFFFFFFFFFFFFFFFEULL); + test_rshift_one(0x00010000U, 60, 0x0000000000000000ULL, 0x0000000000000010ULL); + test_rshift_one(0x80010000U, 60, 0xFFFFFFFFFFFFFFF8ULL, 0x0000000000000010ULL); + test_rshift_one(0x00018000U, 60, 0x0000000000000000ULL, 0x0000000000000018ULL); + test_rshift_one(0x80018000U, 60, 0xFFFFFFFFFFFFFFF8ULL, 0x0000000000000018ULL); + test_rshift_one(0x7FFE0000U, 60, 0x0000000000000007ULL, 0xFFFFFFFFFFFFFFE0ULL); + test_rshift_one(0xFFFE0000U, 60, 0xFFFFFFFFFFFFFFFFULL, 0xFFFFFFFFFFFFFFE0ULL); + test_rshift_one(0x7FFE8000U, 60, 0x0000000000000007ULL, 0xFFFFFFFFFFFFFFE8ULL); + test_rshift_one(0xFFFE8000U, 60, 0xFFFFFFFFFFFFFFFFULL, 0xFFFFFFFFFFFFFFE8ULL); + test_rshift_one(0x00018000U, 0, 0x0000000000000001ULL, 0x8000000000000000ULL); + test_rshift_one(0x80018000U, 0, 0x8000000000000001ULL, 0x8000000000000000ULL); + test_rshift_one(0x7FFE0000U, 0, 0x7FFFFFFFFFFFFFFEULL, 0x0000000000000000ULL); + test_rshift_one(0xFFFE0000U, 0, 0xFFFFFFFFFFFFFFFEULL, 0x0000000000000000ULL); + test_rshift_one(0x7FFE8000U, 0, 0x7FFFFFFFFFFFFFFEULL, 0x8000000000000000ULL); + test_rshift_one(0xFFFE8000U, 0, 0xFFFFFFFFFFFFFFFEULL, 0x8000000000000000ULL); +} + +int main(int argc, char **argv) +{ + g_test_init(&argc, &argv, NULL); + g_test_add_func("/int128/int128_and", test_and); + g_test_add_func("/int128/int128_add", test_add); + g_test_add_func("/int128/int128_sub", test_sub); + g_test_add_func("/int128/int128_neg", test_neg); + g_test_add_func("/int128/int128_nz", test_nz); + g_test_add_func("/int128/int128_le", test_le); + g_test_add_func("/int128/int128_lt", test_lt); + 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); + return g_test_run(); +}