Use <bit> instead of platform-specific intrinsics

Change-Id: I79636ff9c3b2fe601b0b3c94a111b36af0011775
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/164131
Tested-by: Jenkins
Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>

2 files changed, 6 insertions, 49 deletions

diff --git a/tools/source/generic/fract.cxx b/tools/source/generic/fract.cxx
index abe8ee41b206..7dfddf50a880 100644
--- a/tools/source/generic/fract.cxx
+++ b/tools/source/generic/fract.cxx
@@ -25,18 +25,16 @@
 #include <osl/diagnose.h>
 
 #include <algorithm>
+#include <bit>
 #include <cmath>
 #include <numeric>
 
 #include <boost/rational.hpp>
 
-#ifdef _MSC_VER
-#include <intrin.h>
-#endif
-
 static boost::rational<sal_Int32> rational_FromDouble(double dVal);
 static void rational_ReduceInaccurate(boost::rational<sal_Int32>& rRational, unsigned nSignificantBits);
-static int impl_NumberOfBits( sal_uInt32 nNum );
+// Find the number of bits required to represent this number
+static int impl_NumberOfBits(sal_uInt32 nNum) { return 32 - std::countl_zero(nNum); }
 
 static boost::rational<sal_Int32> toRational(sal_Int32 n, sal_Int32 d)
 {
@@ -406,22 +404,6 @@ static boost::rational<sal_Int32> rational_FromDouble(double dVal)
     return boost::rational<sal_Int32>( sal_Int32(dVal), nDen );
 }
 
-/**
- * Find the number of bits required to represent this number, using the CLZ intrinsic
- */
-static int impl_NumberOfBits( sal_uInt32 nNum )
-{
-    if (nNum == 0)
-        return 0;
-#ifdef _MSC_VER
-    unsigned long r = 0;
-    _BitScanReverse(&r, nNum);
-    return r + 1;
-#else
-    return 32 - __builtin_clz(nNum);
-#endif
-}
-
 /** Inaccurate cancellation for a fraction.
 
     Clip both nominator and denominator to said number of bits. If
diff --git a/tools/source/misc/fix16.cxx b/tools/source/misc/fix16.cxx
index 978f77291dce..58c40704d931 100644
--- a/tools/source/misc/fix16.cxx
+++ b/tools/source/misc/fix16.cxx
@@ -24,6 +24,8 @@
 
 #include <tools/fix16.hxx>
 
+#include <bit>
+
 const fix16_t fix16_minimum = 0x80000000; /*!< the minimum value of fix16_t */
 const fix16_t fix16_overflow = 0x80000000; /*!< the value used to indicate overflows */
 
@@ -74,33 +76,6 @@ fix16_t fix16_mul(fix16_t inArg0, fix16_t inArg1)
     return result;
 }
 
-/* 32-bit implementation of fix16_div. Fastest version for e.g. ARM Cortex M3.
- * Performs 32-bit divisions repeatedly to reduce the remainder. For this to
- * be efficient, the processor has to have 32-bit hardware division.
- */
-#ifdef __GNUC__
-// Count leading zeros, using processor-specific instruction if available.
-#define clz(x) (__builtin_clzl(x) - (8 * sizeof(long) - 32))
-#else
-static uint8_t clz(uint32_t x)
-{
-    uint8_t result = 0;
-    if (x == 0)
-        return 32;
-    while (!(x & 0xF0000000))
-    {
-        result += 4;
-        x <<= 4;
-    }
-    while (!(x & 0x80000000))
-    {
-        result += 1;
-        x <<= 1;
-    }
-    return result;
-}
-#endif
-
 fix16_t fix16_div(fix16_t a, fix16_t b)
 {
     // This uses a hardware 32/32 bit division multiple times, until we have
@@ -135,7 +110,7 @@ fix16_t fix16_div(fix16_t a, fix16_t b)
     while (remainder && bit_pos >= 0)
     {
         // Shift remainder as much as we can without overflowing
-        int shift = clz(remainder);
+        int shift = std::countl_zero(remainder);
         if (shift > bit_pos)
             shift = bit_pos;
         remainder <<= shift;