collapseos/forth/parse.fs
Virgil Dupras b062a9092a parse: use "0<" instead of "0 <"
As I wrote in my "Clarify signed-ness" commit, "0 <" is broken.

Also, made this unit a bit more compact. The RC2014 stage1 can
really use some breathing room...
2020-04-18 09:18:09 -04:00

85 lines
2.3 KiB
Forth

( requires core, str )
( string being sent to parse routines are always null
terminated )
: (parsec) ( a -- n f )
( apostrophe is ASCII 39 )
DUP C@ 39 = NOT IF 0 EXIT THEN ( a 0 )
DUP 2+ C@ 39 = NOT IF 0 EXIT THEN ( a 0 )
( surrounded by apos, good, return )
1+ C@ 1 ( n 1 )
;
( returns negative value on error )
: _ ( c -- n )
( '0' is ASCII 48 )
48 -
DUP 0< IF EXIT THEN ( bad )
DUP 10 < IF EXIT THEN ( good )
( 'a' is ASCII 97. 59 = 97 - 48 )
49 -
DUP 0< IF EXIT THEN ( bad )
DUP 6 < IF 10 + EXIT THEN ( good )
( bad )
255 -
;
: (parseh) ( a -- n f )
( '0': ASCII 0x30 'x': 0x78 0x7830: 30768 )
DUP @ 30768 = NOT IF 0 EXIT THEN ( a 0 )
( We have "0x" prefix )
2+
( validate slen )
DUP SLEN ( a l )
DUP NOT IF DROP 0 EXIT THEN ( a 0 )
4 > IF DROP 0 EXIT THEN ( a 0 )
0 ( a r )
BEGIN
SWAP C@+ ( r a+1 c )
DUP NOT IF 2DROP 1 EXIT THEN ( r, 1 )
_ ( r a n )
DUP 0< IF ROT 2DROP 0 EXIT THEN ( a 0 )
ROT 16 * + ( a r*16+n )
AGAIN
;
( returns negative value on error )
: _ ( 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
SWAP C@+ ( r a+1 c )
DUP NOT IF 2DROP 1 EXIT THEN ( r 1 )
_ ( r a n )
DUP 0< IF ROT 2DROP 0 EXIT THEN ( a 0 )
ROT 2 * + ( a r*2+n )
AGAIN
;
: (parse) ( a -- n )
(parsec) IF EXIT THEN
(parseh) IF EXIT THEN
(parseb) IF EXIT THEN
(parsed) IF EXIT THEN
( nothing works )
LIT< (wnf) (find) IF EXECUTE ELSE ABORT THEN
;
' (parse) (parse*) !