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collapseos/apps/basic/tok.asm
2019-12-23 19:13:44 -05:00

98 lines
1.7 KiB
NASM

; Whether A is a separator or end-of-string (null or ':')
isSepOrEnd:
or a
ret z
cp ':'
ret z
; continue to isSep
; Sets Z is A is ' ' or '\t' (whitespace)
isSep:
cp ' '
ret z
cp 0x09
ret
; Expect at least one whitespace (0x20, 0x09) at (HL), and then advance HL
; until a non-whitespace character is met.
; HL is advanced to the first non-whitespace char.
; Sets Z on success, unset on failure.
; Failure is either not having a first whitespace or reaching the end of the
; string.
; Sets Z if we found a non-whitespace char, unset if we found the end of string.
rdSep:
ld a, (hl)
call isSep
ret nz ; failure
.loop:
inc hl
ld a, (hl)
call isSep
jr z, .loop
call isSepOrEnd
jp z, .fail ; unexpected EOL. fail
cp a ; ensure Z
ret
.fail:
; A is zero at this point
inc a ; unset Z
ret
; Advance HL to the next separator or to the end of string.
toSepOrEnd:
ld a, (hl)
call isSepOrEnd
ret z
inc hl
jr toSepOrEnd
; Advance HL to the end of the line, that is, either a null terminating char
; or the ':'.
; Sets Z if we met a null char, unset if we met a ':'
toEnd:
ld a, (hl)
or a
ret z
cp ':'
jr z, .havesep
inc hl
call skipQuoted
jr toEnd
.havesep:
inc a ; unset Z
ret
; Read (HL) until the next separator and copy it in (DE)
; DE is preserved, but HL is advanced to the end of the read word.
rdWord:
push af
push de
.loop:
ld a, (hl)
call isSepOrEnd
jr z, .stop
ld (de), a
inc hl
inc de
jr .loop
.stop:
xor a
ld (de), a
pop de
pop af
ret
; Read word from HL in SCRATCHPAD and then intepret that word as an expression.
; Put the result in IX.
; Z for success.
; TODO: put result in DE
rdExpr:
ld de, SCRATCHPAD
call rdWord
push hl
ex de, hl
call parseExpr
push de \ pop ix
pop hl
ret