ImagerFontAtomImpl.mesa
Copyright © 1984, 1985 by Xerox Corporation. All rights reserved.
Doug Wyatt, May 22, 1985 5:19:35 pm PDT
DIRECTORY
Checksum USING [ComputeChecksum],
ImagerFontPrivate USING [FontAtom, FontAtomRep],
ImagerTransformation USING [Copy, Equal, Transformation, TransformationRep],
ImagerTypeface USING [Typeface],
PrincOps USING [zXOR];
ImagerFontAtomImpl: CEDAR MONITOR
IMPORTS Checksum, ImagerTransformation
EXPORTS ImagerFontPrivate
~ BEGIN
FontAtom: TYPE ~ ImagerFontPrivate.FontAtom;
FontAtomRep: TYPE ~ ImagerFontPrivate.FontAtomRep;
Typeface: TYPE ~ ImagerTypeface.Typeface;
Transformation: TYPE ~ ImagerTransformation.Transformation;
TransformationRep: TYPE ~ ImagerTransformation.TransformationRep;
hashTableSize: NAT ~ 253;
HashIndex: TYPE ~ [0..hashTableSize);
HashTable: TYPE ~ REF HashTableRep;
HashTableRep: TYPE ~ ARRAY HashIndex OF FontAtomList;
FontAtomList: TYPE ~ LIST OF FontAtom;
hashTable: HashTable ~ NEW[HashTableRep ← ALL[NIL]];
entries: INT ← 0;
collisions: INT ← 0;
misses: INT ← 0;
Munch:
PROC [
LONG
CARDINAL]
RETURNS [
CARDINAL]
~ TRUSTED MACHINE CODE { PrincOps.zXOR };
Hash:
PROC [typeface: Typeface, m: Transformation]
RETURNS [
CARDINAL] ~
TRUSTED
INLINE {
RETURN[Checksum.ComputeChecksum[cs: Munch[LOOPHOLE[typeface]],
nWords: SIZE[TransformationRep], p: LOOPHOLE[m]]];
};
MakeFontAtom:
PUBLIC
ENTRY
PROC [typeface: Typeface, m: Transformation]
RETURNS [FontAtom] ~ {
ENABLE UNWIND => NULL;
hash: CARDINAL ~ Hash[typeface, m];
hashIndex: HashIndex ~ hash MOD hashTableSize;
head: FontAtomList ~ hashTable[hashIndex];
FOR each: FontAtomList ← head, each.rest
UNTIL each=
NIL
DO
f: FontAtom ~ each.first;
IF f.typeface=typeface AND ImagerTransformation.Equal[f.m, m] THEN RETURN[f]
ELSE misses ← misses+1;
ENDLOOP;
{
f: FontAtom ~ NEW[FontAtomRep ← [typeface: typeface, m: ImagerTransformation.Copy[m]]];
hashTable[hashIndex] ← CONS[f, head];
entries ← entries+1;
IF head#NIL THEN collisions ← collisions+1;
RETURN[f];
};
};
END.