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Optimize byte-reverse macro in alien.endian -- it was shifting each byte to the 0th bit place, bitand-ing it with HEX: ff, then shifting it to its final destination -- now we immediately shift to the proper location and bitand with the proper bitmask.

db4
Doug Coleman 2011-10-11 19:36:22 -07:00
parent 250e528209
commit 757889167a
1 changed files with 9 additions and 1 deletions
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10
basis/alien/endian/endian.factor
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@ -18,13 +18,21 @@ ERROR: invalid-signed-conversion n ;
[ invalid-signed-conversion ] [ invalid-signed-conversion ]
} case ; inline } case ; inline
<PRIVATE
: byte-mask ( #bits-shift -- mask )
[ HEX: ff ] dip shift ; foldable
PRIVATE>
MACRO: byte-reverse ( n signed? -- quot ) MACRO: byte-reverse ( n signed? -- quot )
[ [
drop drop
[ [
dup iota [ dup iota [
[ 1 + - -8 * ] [ nip 8 * ] 2bi [ 1 + - -8 * ] [ nip 8 * ] 2bi
'[ _ shift HEX: ff bitand _ shift ] [ + ] [ nip byte-mask ] 2bi
'[ _ shift _ bitand ]
] with map ] with map
] [ 1 - [ bitor ] n*quot ] bi ] [ 1 - [ bitor ] n*quot ] bi
] [ ] [