mirror of
https://github.com/hsoft/collapseos.git
synced 2024-11-21 00:38:07 +11:00
89 lines
1.6 KiB
NASM
89 lines
1.6 KiB
NASM
; Sets Z is A is ' ' or '\t' (whitespace)
|
|
isWS:
|
|
cp ' '
|
|
ret z
|
|
cp 0x09
|
|
ret
|
|
|
|
; Copy string from (HL) in (DE), that is, copy bytes until a null char is
|
|
; encountered. The null char is also copied.
|
|
; HL and DE point to the char right after the null char.
|
|
strcpyM:
|
|
ld a, (hl)
|
|
ld (de), a
|
|
inc hl
|
|
inc de
|
|
or a
|
|
jr nz, strcpyM
|
|
ret
|
|
|
|
; Like strcpyM, but preserve HL and DE
|
|
strcpy:
|
|
push hl
|
|
push de
|
|
call strcpyM
|
|
pop de
|
|
pop hl
|
|
ret
|
|
|
|
; Compares strings pointed to by HL and DE until one of them hits its null char.
|
|
; If equal, Z is set. If not equal, Z is reset.
|
|
strcmp:
|
|
push hl
|
|
push de
|
|
|
|
.loop:
|
|
ld a, (de)
|
|
cp (hl)
|
|
jr nz, .end ; not equal? break early. NZ is carried out
|
|
; to the called
|
|
or a ; If our chars are null, stop the cmp
|
|
jr z, .end ; The positive result will be carried to the
|
|
; caller
|
|
inc hl
|
|
inc de
|
|
jr .loop
|
|
|
|
.end:
|
|
pop de
|
|
pop hl
|
|
; Because we don't call anything else than CP that modify the Z flag,
|
|
; our Z value will be that of the last cp (reset if we broke the loop
|
|
; early, set otherwise)
|
|
ret
|
|
|
|
; Given a string at (HL), move HL until it points to the end of that string.
|
|
strskip:
|
|
push af
|
|
xor a ; look for null char
|
|
.loop:
|
|
cp (hl)
|
|
jp z, .found
|
|
inc hl
|
|
jr .loop
|
|
.found:
|
|
pop af
|
|
ret
|
|
|
|
; Returns length of string at (HL) in A.
|
|
; Doesn't include null termination.
|
|
strlen:
|
|
push bc
|
|
push hl
|
|
ld bc, 0
|
|
xor a ; look for null char
|
|
.loop:
|
|
cpi
|
|
jp z, .found
|
|
jr .loop
|
|
.found:
|
|
; How many char do we have? the (NEG BC)-1, which started at 0 and
|
|
; decreased at each CPI call. In this routine, we stay in the 8-bit
|
|
; realm, so C only.
|
|
ld a, c
|
|
neg
|
|
dec a
|
|
pop hl
|
|
pop bc
|
|
ret
|