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Code Issues 4 Releases Wiki Activity

* src/pcf/pcfutil.c ({Two,Four}ByteSwap): Use builtins or shifts. 

We trust glibc which uses shifts or builtins to swap bytes.  This
must be more efficient.
This commit is contained in:
Alexei Podtelezhnikov 2022-11-14 22:53:14 -05:00
parent e6fda039ad
commit 47e61d02e6
1 changed files with 33 additions and 18 deletions
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51
src/pcf/pcfutil.c
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@ -57,6 +57,33 @@ in this Software without prior written authorization from The Open Group.
}
#if defined( __clang__ ) || ( defined( __GNUC__ ) && \
( __GNUC__ > 4 || ( __GNUC__ == 4 && __GNUC_MINOR__ >= 8 ) ) )
#define BSWAP16( x ) __builtin_bswap16( x )
#define BSWAP32( x ) __builtin_bswap32( x )
#elif defined( _MSC_VER ) && _MSC_VER >= 1300
#pragma intrinsic( _byteswap_ushort )
#pragma intrinsic( _byteswap_ulong )
#define BSWAP16( x ) _byteswap_ushort( x )
#define BSWAP32( x ) _byteswap_ulong( x )
#else
#define BSWAP16( x ) \
(FT_UInt16)( ( ( ( x ) >> 8 ) & 0xff ) | \
( ( ( x ) & 0xff ) << 8 ) )
#define BSWAP32( x ) \
(FT_UInt32)( ( ( ( x ) & 0xff000000u ) >> 24 ) | \
( ( ( x ) & 0x00ff0000u ) >> 8 ) | \
( ( ( x ) & 0x0000ff00u ) << 8 ) | \
( ( ( x ) & 0x000000ffu ) << 24 ) )
#endif
/*
* Invert byte order within each 16-bits of an array.
*/
@ -65,15 +92,11 @@ in this Software without prior written authorization from The Open Group.
TwoByteSwap( unsigned char* buf,
size_t nbytes )
{
for ( ; nbytes >= 2; nbytes -= 2, buf += 2 )
{
unsigned char c;
FT_UInt16* b = (FT_UInt16*)buf;
c = buf[0];
buf[0] = buf[1];
buf[1] = c;
}
for ( ; nbytes >= 2; nbytes -= 2, b++ )
*b = BSWAP16( *b );
}
/*
@ -84,19 +107,11 @@ in this Software without prior written authorization from The Open Group.
FourByteSwap( unsigned char* buf,
size_t nbytes )
{
for ( ; nbytes >= 4; nbytes -= 4, buf += 4 )
{
unsigned char c;
FT_UInt32* b = (FT_UInt32*)buf;
c = buf[0];
buf[0] = buf[3];
buf[3] = c;
c = buf[1];
buf[1] = buf[2];
buf[2] = c;
}
for ( ; nbytes >= 4; nbytes -= 4, b++ )
*b = BSWAP32( *b );
}