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[sfnt] Implement PS names for font instances [1/3].

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Add 128bit MurmurHash 3 function.

Everything is guarded with TT_CONFIG_OPTION_GX_VAR_SUPPORT.

* src/sfnt/sfdriver.c (ROTL32): New macro.
(fmix32, murmur_hash_3_128): New functions.
This commit is contained in:
Werner Lemberg 2017-03-14 19:32:12 +01:00
parent 447a0b6263
commit 4a32dce92a
2 changed files with 200 additions and 0 deletions
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11
ChangeLog
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@ -1,3 +1,14 @@
2017-03-14 Werner Lemberg <wl@gnu.org>
[sfnt] Implement PS names for font instances [1/3].
Add 128bit MurmurHash 3 function.
Everything is guarded with TT_CONFIG_OPTION_GX_VAR_SUPPORT.
* src/sfnt/sfdriver.c (ROTL32): New macro.
(fmix32, murmur_hash_3_128): New functions.
2017-03-13 Werner Lemberg <wl@gnu.org>
[truetype] Ignore invalid MVAR tags.

189
src/sfnt/sfdriver.c
View File

@ -250,6 +250,195 @@
}
#ifdef TT_CONFIG_OPTION_GX_VAR_SUPPORT
/* the implementation of MurmurHash3 is taken and adapted from */
/* https://github.com/aappleby/smhasher/blob/master/src/MurmurHash3.cpp */
#define ROTL32( x, r ) ( x << r ) | ( x >> ( 32 - r ) )
FT_UInt32
fmix32( FT_UInt32 h )
{
h ^= h >> 16;
h *= 0x85ebca6b;
h ^= h >> 13;
h *= 0xc2b2ae35;
h ^= h >> 16;
return h;
}
void
murmur_hash_3_128( const void* key,
const int len,
FT_UInt32 seed,
void* out )
{
const FT_Byte* data = (const FT_Byte*)key;
const int nblocks = len / 16;
FT_UInt32 h1 = seed;
FT_UInt32 h2 = seed;
FT_UInt32 h3 = seed;
FT_UInt32 h4 = seed;
const FT_UInt32 c1 = 0x239b961b;
const FT_UInt32 c2 = 0xab0e9789;
const FT_UInt32 c3 = 0x38b34ae5;
const FT_UInt32 c4 = 0xa1e38b93;
const FT_UInt32* blocks = (const FT_UInt32*)( data + nblocks * 16 );
int i;
for( i = -nblocks; i; i++ )
{
FT_UInt32 k1 = blocks[i * 4 + 0];
FT_UInt32 k2 = blocks[i * 4 + 1];
FT_UInt32 k3 = blocks[i * 4 + 2];
FT_UInt32 k4 = blocks[i * 4 + 3];
k1 *= c1;
k1 = ROTL32( k1, 15 );
k1 *= c2;
h1 ^= k1;
h1 = ROTL32( h1, 19 );
h1 += h2;
h1 = h1 * 5 + 0x561ccd1b;
k2 *= c2;
k2 = ROTL32( k2, 16 );
k2 *= c3;
h2 ^= k2;
h2 = ROTL32( h2, 17 );
h2 += h3;
h2 = h2 * 5 + 0x0bcaa747;
k3 *= c3;
k3 = ROTL32( k3, 17 );
k3 *= c4;
h3 ^= k3;
h3 = ROTL32( h3, 15 );
h3 += h4;
h3 = h3 * 5 + 0x96cd1c35;
k4 *= c4;
k4 = ROTL32( k4, 18 );
k4 *= c1;
h4 ^= k4;
h4 = ROTL32( h4, 13 );
h4 += h1;
h4 = h4 * 5 + 0x32ac3b17;
}
{
const FT_Byte* tail = (const FT_Byte*)( data + nblocks * 16 );
FT_UInt32 k1 = 0;
FT_UInt32 k2 = 0;
FT_UInt32 k3 = 0;
FT_UInt32 k4 = 0;
switch ( len & 15 )
{
case 15:
k4 ^= tail[14] << 16;
case 14:
k4 ^= tail[13] << 8;
case 13:
k4 ^= tail[12] << 0;
k4 *= c4;
k4 = ROTL32( k4, 18 );
k4 *= c1;
h4 ^= k4;
case 12:
k3 ^= tail[11] << 24;
case 11:
k3 ^= tail[10] << 16;
case 10:
k3 ^= tail[9] << 8;
case 9:
k3 ^= tail[8] << 0;
k3 *= c3;
k3 = ROTL32( k3, 17 );
k3 *= c4;
h3 ^= k3;
case 8:
k2 ^= tail[7] << 24;
case 7:
k2 ^= tail[6] << 16;
case 6:
k2 ^= tail[5] << 8;
case 5:
k2 ^= tail[4] << 0;
k2 *= c2;
k2 = ROTL32( k2, 16 );
k2 *= c3;
h2 ^= k2;
case 4:
k1 ^= tail[3] << 24;
case 3:
k1 ^= tail[2] << 16;
case 2:
k1 ^= tail[1] << 8;
case 1:
k1 ^= tail[0] << 0;
k1 *= c1;
k1 = ROTL32( k1, 15 );
k1 *= c2;
h1 ^= k1;
}
}
h1 ^= len;
h2 ^= len;
h3 ^= len;
h4 ^= len;
h1 += h2;
h1 += h3;
h1 += h4;
h2 += h1;
h3 += h1;
h4 += h1;
h1 = fmix32( h1 );
h2 = fmix32( h2 );
h3 = fmix32( h3 );
h4 = fmix32( h4 );
h1 += h2;
h1 += h3;
h1 += h4;
h2 += h1;
h3 += h1;
h4 += h1;
((FT_UInt32*)out)[0] = h1;
((FT_UInt32*)out)[1] = h2;
((FT_UInt32*)out)[2] = h3;
((FT_UInt32*)out)[3] = h4;
}
#endif /* TT_CONFIG_OPTION_GX_VAR_SUPPORT */
typedef int (*char_type_func)( int c );