minor optimisations in ftcalc.c

This commit is contained in:
David Turner 2001-04-26 00:21:48 +00:00
parent ec46b28df7
commit c2cd00443b
1 changed files with 101 additions and 90 deletions

View File

@ -189,7 +189,6 @@
#ifdef FT_CONFIG_OPTION_OLD_CALCS
#if 0
/* a helper function for FT_Sqrt64() */
static
@ -229,23 +228,99 @@
return r;
}
FT_EXPORT_DEF( FT_Int32 ) FT_SqrtFixed( FT_Int32 x )
{
FT_Int64 z;
z = (FT_Int64)(x) << 16;
return FT_Sqrt64( z );
}
#endif
#endif /* FT_CONFIG_OPTION_OLD_CALCS */
#else /* FT_LONG64 */
static void
ft_multo64( FT_UInt32 x,
FT_UInt32 y,
FT_Int64 *z )
{
{
FT_UInt32 lo1, hi1, lo2, hi2, lo, hi, i1, i2;
lo1 = x & 0x0000FFFFU; hi1 = x >> 16;
lo2 = y & 0x0000FFFFU; hi2 = y >> 16;
lo = lo1 * lo2;
i1 = lo1 * hi2;
i2 = lo2 * hi1;
hi = hi1 * hi2;
/* Check carry overflow of i1 + i2 */
i1 += i2;
hi += (FT_UInt32)( i1 < i2 ) << 16;
hi += i1 >> 16;
i1 = i1 << 16;
/* Check carry overflow of i1 + lo */
lo += i1;
hi += ( lo < i1 );
z->lo = lo;
z->hi = hi;
}
}
static FT_UInt32
ft_div64by32( FT_UInt32 hi,
FT_UInt32 lo,
FT_UInt32 y )
{
FT_UInt r, q;
FT_Int i;
q = 0;
r = hi;
if ( r >= y )
return (FT_UInt32)0x7FFFFFFF;
i = 32;
do
{
r <<= 1;
q <<= 1;
r |= lo >> 31;
if ( r >= (FT_UInt32)y )
{
r -= y;
q |= 1;
}
lo <<= 1;
}
while (--i);
return q;
}
/* documentation is in ftcalc.h */
FT_EXPORT_DEF( void ) FT_Add64( FT_Int64* x,
FT_Int64* y,
FT_Int64 *z )
{
register FT_UInt32 lo, hi, max;
max = x->lo > y->lo ? x->lo : y->lo;
lo = x->lo + y->lo;
hi = x->hi + y->hi + ( lo < max );
z->lo = lo;
z->hi = hi;
}
/* documentation is in freetype.h */
FT_EXPORT_DEF( FT_Long ) FT_MulDiv( FT_Long a,
@ -271,11 +346,12 @@
FT_Int64 temp, temp2;
FT_MulTo64( a, b, &temp );
temp2.hi = (FT_Int32)( c >> 31 );
temp2.lo = (FT_UInt32)( c / 2 );
FT_Add64( &temp, &temp2, &temp );
a = FT_Div64by32( &temp, c );
ft_multo64( a, b, &temp );
temp2.hi = 0;
temp2.lo = (FT_UInt32)(c >> 1);
FT_Add64( &temp, &temp2, &temp );
a = ft_div64by32( temp.hi, temp.lo, b );
}
else
a = 0x7FFFFFFFL;
@ -339,7 +415,7 @@
else if ( ( a >> 16 ) == 0 )
{
/* compute result directly */
q = (FT_UInt32)( a << 16 ) / (FT_UInt32)b;
q = (FT_UInt32)( (a << 16) + (b >> 1) ) / (FT_UInt32)b;
}
else
{
@ -348,33 +424,16 @@
temp.hi = (FT_Int32) (a >> 16);
temp.lo = (FT_UInt32)(a << 16);
temp2.hi = (FT_Int32)( b >> 31 );
temp2.lo = (FT_UInt32)( b / 2 );
temp2.hi = 0;
temp2.lo = (FT_UInt32)( b >> 1 );
FT_Add64( &temp, &temp2, &temp );
q = FT_Div64by32( &temp, b );
q = ft_div64by32( temp.hi, temp.lo, b );
}
return ( s < 0 ? -(FT_Int32)q : (FT_Int32)q );
}
/* documentation is in ftcalc.h */
FT_EXPORT_DEF( void ) FT_Add64( FT_Int64* x,
FT_Int64* y,
FT_Int64 *z )
{
register FT_UInt32 lo, hi;
lo = x->lo + y->lo;
hi = x->hi + y->hi + ( lo < x->lo );
z->lo = lo;
z->hi = hi;
}
/* documentation is in ftcalc.h */
FT_EXPORT_DEF( void ) FT_MulTo64( FT_Int32 x,
@ -387,34 +446,7 @@
s = x; x = ABS( x );
s ^= y; y = ABS( y );
{
FT_UInt32 lo1, hi1, lo2, hi2, lo, hi, i1, i2;
lo1 = x & 0x0000FFFF; hi1 = x >> 16;
lo2 = y & 0x0000FFFF; hi2 = y >> 16;
lo = lo1 * lo2;
i1 = lo1 * hi2;
i2 = lo2 * hi1;
hi = hi1 * hi2;
/* Check carry overflow of i1 + i2 */
i1 += i2;
if ( i1 < i2 )
hi += 1L << 16;
hi += i1 >> 16;
i1 = i1 << 16;
/* Check carry overflow of i1 + lo */
lo += i1;
hi += ( lo < i1 );
z->lo = lo;
z->hi = hi;
}
ft_multo64( x, y, z );
if ( s < 0 )
{
z->lo = (FT_UInt32)-(FT_Int32)z->lo;
@ -429,7 +461,7 @@
FT_Int32 y )
{
FT_Int32 s;
FT_UInt32 q, r, i, lo;
FT_UInt32 q;
s = x->hi;
@ -444,35 +476,14 @@
if ( x->hi == 0 )
{
if ( y > 0 )
q = x->lo / y;
q = (x->lo + (y >> 1)) / y;
else
q = 0x7FFFFFFFL;
return ( s < 0 ? -(FT_Int32)q : (FT_Int32)q );
}
r = x->hi;
lo = x->lo;
if ( r >= (FT_UInt32)y ) /* we know y is to be treated as unsigned here */
return ( s < 0 ? 0x80000001UL : 0x7FFFFFFFUL );
/* Return Max/Min Int32 if division overflow. */
/* This includes division by zero! */
q = 0;
for ( i = 0; i < 32; i++ )
{
r <<= 1;
q <<= 1;
r |= lo >> 31;
if ( r >= (FT_UInt32)y )
{
r -= y;
q |= 1;
}
lo <<= 1;
}
q = ft_div64by32( x->hi, x->lo, y );
return ( s < 0 ? -(FT_Int32)q : (FT_Int32)q );
}