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forth: implement "0b" number parsing

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This commit is contained in:
Virgil Dupras 2020-03-19 16:03:35 -04:00
parent f0cbda1f2e
commit af5a97243a
2 changed files with 34 additions and 1 deletions
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33
forth/parse.fs
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@ -27,7 +27,7 @@
: (parseh) ( a -- n f ) : (parseh) ( a -- n f )
( '0': ASCII 0x30 'x': 0x78 0x7830: 30768 ) ( '0': ASCII 0x30 'x': 0x78 0x7830: 30768 )
DUP @ 30768 = NOT IF 0 EXIT THEN ( a 0 ) DUP @ 30768 = NOT IF 0 EXIT THEN ( a 0 )
( We have "0x" suffix ) ( We have "0x" prefix )
2 + 2 +
( validate slen ) ( validate slen )
DUP SLEN ( a l ) DUP SLEN ( a l )
@ -44,9 +44,40 @@
AGAIN AGAIN
; ;
( returns negative value on error )
: bindig ( c -- n )
( '0' is ASCII 48 )
48 -
DUP 0 < IF EXIT THEN ( bad )
DUP 2 < IF EXIT THEN ( good )
( bad )
255 -
;
: (parseb) ( a -- n f )
( '0': ASCII 0x30 'b': 0x62 0x6230: 25136 )
DUP @ 25136 = NOT IF 0 EXIT THEN ( a 0 )
( We have "0b" prefix )
2 +
( validate slen )
DUP SLEN ( a l )
DUP 0 = IF DROP 0 EXIT THEN ( a 0 )
16 > IF DROP 0 EXIT THEN ( a 0 )
0 ( a r )
BEGIN
OVER C@
DUP 0 = IF DROP SWAP DROP 1 EXIT THEN ( r, 1 )
bindig ( a r n )
DUP 0 < IF DROP DROP 1 EXIT THEN ( a 0 )
SWAP 2 * + ( a r*2+n )
SWAP 1 + SWAP ( a+1 r )
AGAIN
;
: (parse) ( a -- n ) : (parse) ( a -- n )
(parsec) NOT SKIP? EXIT (parsec) NOT SKIP? EXIT
(parseh) NOT SKIP? EXIT (parseh) NOT SKIP? EXIT
(parseb) NOT SKIP? EXIT
(parsed) NOT SKIP? EXIT (parsed) NOT SKIP? EXIT
( nothing works ) ( nothing works )
ABORT" unknown word! " ABORT" unknown word! "

2
tests/forth/test_parse.fs Normal file
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@ -0,0 +1,2 @@
'b' 0x62 #eq
0b1111010101 981 #eq