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cc65/libsrc/common/fgets.s
Colin Leroy-Mira 1f820d0ae8 Rewrite fgets in asm
-104 bytes, -1% cycles
2024-01-24 10:16:26 +01:00

120 lines
2.4 KiB
ArmAsm

;
; Colin Leroy-Mira, 2024
;
; char* __fastcall__ fgets (char* s, unsigned size, register FILE* f)
;
.export _fgets
.import _fgetc, popptr1, pushptr1, popax, pushax, return0, ___errno
.importzp ptr1, ptr4
.include "errno.inc"
.include "stdio.inc"
.include "_file.inc"
.macpack cpu
terminate_ptr:
lda #$00
tax
.if (.cpu .bitand ::CPU_ISET_65SC02)
sta (ptr4)
.else
tay
sta (ptr4),y
.endif
rts
_fgets:
sta ptr1
stx ptr1+1
jsr popax
sta size
stx size+1
jsr popax
sta ptr4
stx ptr4+1
sta buf
stx buf+1
.if (.cpu .bitand ::CPU_ISET_65SC02)
stz didread
.else
lda #$00 ; We have read nothing yet
sta didread
.endif
; Check size
lda size
ora size+1
bne read_loop
lda #EINVAL
sta ___errno
jmp return0
read_loop:
lda size ; Dec size
bne :+
dec size+1
: dec size
bne :+ ; Check bound
ldx size+1
beq done
: jsr pushptr1 ; Push ptr1 for backup and load it to AX for fgetc
jsr _fgetc ; Read a char
pha
jsr popptr1 ; Get ptr1 back
pla
cpx #<EOF
beq got_eof
ldy #$01
sty didread ; We read at least one char
.if (.cpu .bitand ::CPU_ISET_65SC02)
sta (ptr4)
.else
dey
sta (ptr4),y
.endif
inc ptr4
bne :+
inc ptr4+1
: cmp #$0A ; Stop at \n
beq done
clc
bcc read_loop
got_eof:
lda didread
beq stopped_at_first_char
ldy #_FILE::f_flags
lda (ptr1),y
and #_FERROR
bne stopped_at_first_char
done:
jsr terminate_ptr
ldx #>buf
lda #<buf
rts
stopped_at_first_char:
jmp terminate_ptr
.bss
c: .res 1
buf: .res 2
size: .res 2
didread:.res 1