From 3bc815a5dc18a646334ba933c74ce7ce44099625 Mon Sep 17 00:00:00 2001
From: Fernando Sahmkow <fsahmkow27@gmail.com>
Date: Fri, 15 Mar 2019 23:18:11 -0400
Subject: [PATCH] Implement intrinsics CountTrailingZeroes and test it.
---
src/common/bit_util.h | 45 +++++++++++++++++++++++++---------
src/tests/CMakeLists.txt | 1 +
src/tests/common/bit_utils.cpp | 42 +++++++++++++++++++++++++++++++
3 files changed, 76 insertions(+), 12 deletions(-)
create mode 100644 src/tests/common/bit_utils.cpp
diff --git a/src/common/bit_util.h b/src/common/bit_util.h
index 14e53c2732..70e728a5ef 100644
--- a/src/common/bit_util.h
+++ b/src/common/bit_util.h
@@ -59,22 +59,43 @@ inline u64 CountLeadingZeroes64(u64 value) {
}
#endif
+
+#ifdef _MSC_VER
inline u32 CountTrailingZeroes32(u32 value) {
- u32 count = 0;
- while (((value >> count) & 0xf) == 0 && count < 32)
- count += 4;
- while (((value >> count) & 1) == 0 && count < 32)
- count++;
- return count;
+ unsigned long trailing_zero = 0;
+
+ if (_BitScanForward(&trailing_zero, value) != 0) {
+ return trailing_zero;
+ }
+
+ return 32;
}
inline u64 CountTrailingZeroes64(u64 value) {
- u64 count = 0;
- while (((value >> count) & 0xf) == 0 && count < 64)
- count += 4;
- while (((value >> count) & 1) == 0 && count < 64)
- count++;
- return count;
+ unsigned long trailing_zero = 0;
+
+ if (_BitScanForward64(&trailing_zero, value) != 0) {
+ return trailing_zero;
+ }
+
+ return 64;
+}
+#else
+inline u32 CountTrailingZeroes32(u32 value) {
+ if (value == 0) {
+ return 32;
+ }
+
+ return __builtin_ctz(value);
}
+inline u64 CountTrailingZeroes64(u64 value) {
+ if (value == 0) {
+ return 64;
+ }
+
+ return __builtin_ctzll(value);
+}
+#endif
+
} // namespace Common
diff --git a/src/tests/CMakeLists.txt b/src/tests/CMakeLists.txt
index d0284bdf4c..f38267be89 100644
--- a/src/tests/CMakeLists.txt
+++ b/src/tests/CMakeLists.txt
@@ -1,5 +1,6 @@
add_executable(tests
common/bit_field.cpp
+ common/bit_utils.cpp
common/param_package.cpp
common/ring_buffer.cpp
core/arm/arm_test_common.cpp
diff --git a/src/tests/common/bit_utils.cpp b/src/tests/common/bit_utils.cpp
new file mode 100644
index 0000000000..77c17c526b
--- /dev/null
+++ b/src/tests/common/bit_utils.cpp
@@ -0,0 +1,42 @@
+// Copyright 2017 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include <catch2/catch.hpp>
+#include <math.h>
+#include "common/bit_util.h"
+
+namespace Common {
+
+inline u32 CTZ32(u32 value) {
+ u32 count = 0;
+ while (((value >> count) & 0xf) == 0 && count < 32)
+ count += 4;
+ while (((value >> count) & 1) == 0 && count < 32)
+ count++;
+ return count;
+}
+
+inline u64 CTZ64(u64 value) {
+ u64 count = 0;
+ while (((value >> count) & 0xf) == 0 && count < 64)
+ count += 4;
+ while (((value >> count) & 1) == 0 && count < 64)
+ count++;
+ return count;
+}
+
+
+TEST_CASE("BitUtils", "[common]") {
+ REQUIRE(Common::CountTrailingZeroes32(0) == CTZ32(0));
+ REQUIRE(Common::CountTrailingZeroes64(0) == CTZ64(0));
+ REQUIRE(Common::CountTrailingZeroes32(9) == CTZ32(9));
+ REQUIRE(Common::CountTrailingZeroes32(8) == CTZ32(8));
+ REQUIRE(Common::CountTrailingZeroes32(0x801000) == CTZ32(0x801000));
+ REQUIRE(Common::CountTrailingZeroes64(9) == CTZ64(9));
+ REQUIRE(Common::CountTrailingZeroes64(8) == CTZ64(8));
+ REQUIRE(Common::CountTrailingZeroes64(0x801000) == CTZ64(0x801000));
+ REQUIRE(Common::CountTrailingZeroes64(0x801000000000UL) == CTZ64(0x801000000000UL));
+}
+
+} // namespace Common