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host-utils: Implement unsigned quadword left/right shift and unit tests

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Implements 128-bit left shift and right shift as well as their
testcases. By design, shift silently mods by 128, so the caller is
responsible to assert the shift range if necessary.

Left shift sets the overflow flag if any non-zero digit is shifted out.

Examples:
 ulshift(&low, &high, 250, &overflow);
 equivalent: n << 122

 urshift(&low, &high, -2);
 equivalent: n << 126

Signed-off-by: Jose Ricardo Ziviani <joserz@linux.vnet.ibm.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
[dwg: Added test-shift128 to .gitignore]
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
This commit is contained in:
Jose Ricardo Ziviani 2017-01-10 00:10:09 -02:00 committed by David Gibson
parent 6758c192b0
commit f539fbe337
5 changed files with 235 additions and 1 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

27
include/qemu/host-utils.h
View file

@ -513,4 +513,31 @@ static inline uint64_t pow2ceil(uint64_t value)
return 1ULL << (64 - nlz);
}
/**
* urshift - 128-bit Unsigned Right Shift.
* @plow: in/out - lower 64-bit integer.
* @phigh: in/out - higher 64-bit integer.
* @shift: in - bytes to shift, between 0 and 127.
*
* Result is zero-extended and stored in plow/phigh, which are
* input/output variables. Shift values outside the range will
* be mod to 128. In other words, the caller is responsible to
* verify/assert both the shift range and plow/phigh pointers.
*/
void urshift(uint64_t *plow, uint64_t *phigh, int32_t shift);
/**
* ulshift - 128-bit Unsigned Left Shift.
* @plow: in/out - lower 64-bit integer.
* @phigh: in/out - higher 64-bit integer.
* @shift: in - bytes to shift, between 0 and 127.
* @overflow: out - true if any 1-bit is shifted out.
*
* Result is zero-extended and stored in plow/phigh, which are
* input/output variables. Shift values outside the range will
* be mod to 128. In other words, the caller is responsible to
* verify/assert both the shift range and plow/phigh pointers.
*/
void ulshift(uint64_t *plow, uint64_t *phigh, int32_t shift, bool *overflow);
#endif

1
tests/.gitignore vendored
View file

@ -69,6 +69,7 @@ test-qmp-marshal.c
test-qobject-output-visitor
test-rcu-list
test-replication
test-shift128
test-string-input-visitor
test-string-output-visitor
test-thread-pool

5
tests/Makefile.include
View file

@ -65,6 +65,8 @@ check-unit-$(CONFIG_POSIX) += tests/test-vmstate$(EXESUF)
endif
check-unit-y += tests/test-cutils$(EXESUF)
gcov-files-test-cutils-y += util/cutils.c
check-unit-y += tests/test-shift128$(EXESUF)
gcov-files-test-shift128-y = util/host-utils.c
check-unit-y += tests/test-mul64$(EXESUF)
gcov-files-test-mul64-y = util/host-utils.c
check-unit-y += tests/test-int128$(EXESUF)
@ -487,7 +489,7 @@ test-obj-y = tests/check-qint.o tests/check-qstring.o tests/check-qdict.o \
tests/test-x86-cpuid.o tests/test-mul64.o tests/test-int128.o \
tests/test-opts-visitor.o tests/test-qmp-event.o \
tests/rcutorture.o tests/test-rcu-list.o \
tests/test-qdist.o \
tests/test-qdist.o tests/test-shift128.o \
tests/test-qht.o tests/qht-bench.o tests/test-qht-par.o \
tests/atomic_add-bench.o
@ -596,6 +598,7 @@ tests/test-qmp-commands$(EXESUF): tests/test-qmp-commands.o tests/test-qmp-marsh
tests/test-visitor-serialization$(EXESUF): tests/test-visitor-serialization.o $(test-qapi-obj-y)
tests/test-opts-visitor$(EXESUF): tests/test-opts-visitor.o $(test-qapi-obj-y)
tests/test-shift128$(EXESUF): tests/test-shift128.o $(test-util-obj-y)
tests/test-mul64$(EXESUF): tests/test-mul64.o $(test-util-obj-y)
tests/test-bitops$(EXESUF): tests/test-bitops.o $(test-util-obj-y)
tests/test-bitcnt$(EXESUF): tests/test-bitcnt.o $(test-util-obj-y)

139
tests/test-shift128.c Normal file
View file

@ -0,0 +1,139 @@
/*
* Test unsigned left and right shift
*
* 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 "qemu/osdep.h"
#include "qemu/host-utils.h"
typedef struct {
uint64_t low;
uint64_t high;
uint64_t rlow;
uint64_t rhigh;
int32_t shift;
bool overflow;
} test_data;
static const test_data test_ltable[] = {
{ 0x4C7ULL, 0x0ULL, 0x00000000000004C7ULL,
0x0000000000000000ULL, 0, false },
{ 0x001ULL, 0x0ULL, 0x0000000000000002ULL,
0x0000000000000000ULL, 1, false },
{ 0x001ULL, 0x0ULL, 0x0000000000000004ULL,
0x0000000000000000ULL, 2, false },
{ 0x001ULL, 0x0ULL, 0x0000000000000010ULL,
0x0000000000000000ULL, 4, false },
{ 0x001ULL, 0x0ULL, 0x0000000000000100ULL,
0x0000000000000000ULL, 8, false },
{ 0x001ULL, 0x0ULL, 0x0000000000010000ULL,
0x0000000000000000ULL, 16, false },
{ 0x001ULL, 0x0ULL, 0x0000000080000000ULL,
0x0000000000000000ULL, 31, false },
{ 0x001ULL, 0x0ULL, 0x0000200000000000ULL,
0x0000000000000000ULL, 45, false },
{ 0x001ULL, 0x0ULL, 0x1000000000000000ULL,
0x0000000000000000ULL, 60, false },
{ 0x001ULL, 0x0ULL, 0x0000000000000000ULL,
0x0000000000000001ULL, 64, false },
{ 0x001ULL, 0x0ULL, 0x0000000000000000ULL,
0x0000000000010000ULL, 80, false },
{ 0x001ULL, 0x0ULL, 0x0000000000000000ULL,
0x8000000000000000ULL, 127, false },
{ 0x000ULL, 0x1ULL, 0x0000000000000000ULL,
0x0000000000000000ULL, 64, true },
{ 0x008ULL, 0x0ULL, 0x0000000000000000ULL,
0x0000000000000008ULL, 64, false },
{ 0x008ULL, 0x0ULL, 0x0000000000000000ULL,
0x8000000000000000ULL, 124, false },
{ 0x001ULL, 0x0ULL, 0x0000000000000000ULL,
0x4000000000000000ULL, 126, false },
{ 0x001ULL, 0x0ULL, 0x0000000000000000ULL,
0x8000000000000000ULL, 127, false },
{ 0x001ULL, 0x0ULL, 0x0000000000000001ULL,
0x0000000000000000ULL, 128, false },
{ 0x000ULL, 0x0ULL, 0x0000000000000000ULL,
0x0000000000000000ULL, 200, false },
{ 0x001ULL, 0x0ULL, 0x0000000000000000ULL,
0x0000000000000100ULL, 200, false },
{ 0x001ULL, 0x0ULL, 0x0000000000000000ULL,
0x8000000000000000ULL, -1, false },
{ 0x001ULL, 0x0ULL, 0x0000000000000000ULL,
0x8000000000000000ULL, INT32_MAX, false },
{ 0x001ULL, 0x0ULL, 0x0000000000000000ULL,
0x4000000000000000ULL, -2, false },
{ 0x001ULL, 0x0ULL, 0x0000000000000000ULL,
0x4000000000000000ULL, INT32_MAX - 1, false },
{ 0x8888888888888888ULL, 0x9999999999999999ULL,
0x8000000000000000ULL, 0x9888888888888888ULL, 60, true },
{ 0x8888888888888888ULL, 0x9999999999999999ULL,
0x0000000000000000ULL, 0x8888888888888888ULL, 64, true },
};
static const test_data test_rtable[] = {
{ 0x00000000000004C7ULL, 0x0ULL, 0x00000000000004C7ULL, 0x0ULL, 0, false },
{ 0x0800000000000000ULL, 0x0ULL, 0x0400000000000000ULL, 0x0ULL, 1, false },
{ 0x0800000000000000ULL, 0x0ULL, 0x0200000000000000ULL, 0x0ULL, 2, false },
{ 0x0800000000000000ULL, 0x0ULL, 0x0008000000000000ULL, 0x0ULL, 8, false },
{ 0x0800000000000000ULL, 0x0ULL, 0x0000080000000000ULL, 0x0ULL, 16, false },
{ 0x0800000000000000ULL, 0x0ULL, 0x0000000008000000ULL, 0x0ULL, 32, false },
{ 0x8000000000000000ULL, 0x0ULL, 0x0000000000000001ULL, 0x0ULL, 63, false },
{ 0x8000000000000000ULL, 0x0ULL, 0x0000000000000000ULL, 0x0ULL, 64, false },
{ 0x0000000000000000ULL, 0x8000000000000000ULL,
0x0000000000000000ULL, 0x8000000000000000ULL, 128, false },
{ 0x0000000000000000ULL, 0x8000000000000000ULL,
0x0080000000000000ULL, 0x0000000000000000ULL, 200, false },
{ 0x0000000000000000ULL, 0x0000000000000000ULL,
0x0000000000000000ULL, 0x0000000000000000ULL, 200, false },
{ 0x0000000000000000ULL, 0x8000000000000000ULL,
0x0000000000000000ULL, 0x0000000000000080ULL, -200, false },
{ 0x8000000000000000ULL, 0x8000000000000000ULL,
0x0000000080000000ULL, 0x0000000080000000ULL, 32, false },
{ 0x0800000000000000ULL, 0x0800000000000000ULL,
0x0800000000000000ULL, 0x0000000000000000ULL, 64, false },
{ 0x0800000000000000ULL, 0x0800000000000000ULL,
0x0008000000000000ULL, 0x0000000000000000ULL, 72, false },
{ 0x8000000000000000ULL, 0x8000000000000000ULL,
0x0000000000000001ULL, 0x0000000000000000ULL, 127, false },
{ 0x0000000000000000ULL, 0x8000000000000000ULL,
0x0000000000000001ULL, 0x0000000000000000ULL, -1, false },
{ 0x0000000000000000ULL, 0x8000000000000000ULL,
0x0000000000000002ULL, 0x0000000000000000ULL, -2, false },
};
static void test_lshift(void)
{
int i;
for (i = 0; i < ARRAY_SIZE(test_ltable); ++i) {
bool overflow = false;
test_data tmp = test_ltable[i];
ulshift(&tmp.low, &tmp.high, tmp.shift, &overflow);
g_assert_cmpuint(tmp.low, ==, tmp.rlow);
g_assert_cmpuint(tmp.high, ==, tmp.rhigh);
g_assert_cmpuint(tmp.overflow, ==, overflow);
}
}
static void test_rshift(void)
{
int i;
for (i = 0; i < ARRAY_SIZE(test_rtable); ++i) {
test_data tmp = test_rtable[i];
urshift(&tmp.low, &tmp.high, tmp.shift);
g_assert_cmpuint(tmp.low, ==, tmp.rlow);
g_assert_cmpuint(tmp.high, ==, tmp.rhigh);
}
}
int main(int argc, char **argv)
{
g_test_init(&argc, &argv, NULL);
g_test_add_func("/host-utils/test_lshift", test_lshift);
g_test_add_func("/host-utils/test_rshift", test_rshift);
return g_test_run();
}

64
util/host-utils.c
View file

@ -161,3 +161,67 @@ int divs128(int64_t *plow, int64_t *phigh, int64_t divisor)
}
#endif
/**
* urshift - 128-bit Unsigned Right Shift.
* @plow: in/out - lower 64-bit integer.
* @phigh: in/out - higher 64-bit integer.
* @shift: in - bytes to shift, between 0 and 127.
*
* Result is zero-extended and stored in plow/phigh, which are
* input/output variables. Shift values outside the range will
* be mod to 128. In other words, the caller is responsible to
* verify/assert both the shift range and plow/phigh pointers.
*/
void urshift(uint64_t *plow, uint64_t *phigh, int32_t shift)
{
shift &= 127;
if (shift == 0) {
return;
}
uint64_t h = *phigh >> (shift & 63);
if (shift >= 64) {
*plow = h;
*phigh = 0;
} else {
*plow = (*plow >> (shift & 63)) | (*phigh << (64 - (shift & 63)));
*phigh = h;
}
}
/**
* ulshift - 128-bit Unsigned Left Shift.
* @plow: in/out - lower 64-bit integer.
* @phigh: in/out - higher 64-bit integer.
* @shift: in - bytes to shift, between 0 and 127.
* @overflow: out - true if any 1-bit is shifted out.
*
* Result is zero-extended and stored in plow/phigh, which are
* input/output variables. Shift values outside the range will
* be mod to 128. In other words, the caller is responsible to
* verify/assert both the shift range and plow/phigh pointers.
*/
void ulshift(uint64_t *plow, uint64_t *phigh, int32_t shift, bool *overflow)
{
uint64_t low = *plow;
uint64_t high = *phigh;
shift &= 127;
if (shift == 0) {
return;
}
/* check if any bit will be shifted out */
urshift(&low, &high, 128 - shift);
if (low | high) {
*overflow = true;
}
if (shift >= 64) {
*phigh = *plow << (shift & 63);
*plow = 0;
} else {
*phigh = (*plow >> (64 - (shift & 63))) | (*phigh << (shift & 63));
*plow = *plow << shift;
}
}