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|
.module libc
.globl _writes, _putc, _puts, _nl, _strlen, _readc, _sexit, _getpid, _getargs
;; SDCC sm83 sdcccall(1): 1st arg -> A (byte) or DE (pointer); ret A / BC.
;; rst $30 (the trap) clobbers BC/DE/HL; SDCC treats them caller-saved, so
;; wrappers need not preserve them - but we compute cleanly regardless.
.area _CODE
;; void writes(const char *buf /*DE*/, unsigned char len /*A*/)
_writes:
ld b, a
ld c, #3 ; SYS_WRITE
rst #0x30
ret
;; char *getargs(void) -> BC : the arg string (command line past word 1).
;; The shell leaves "cmd\0args\0" at 0xA000, inherited by the child via fork.
_getargs:
ld hl, #0xa000
1$: ld a, (hl)
inc hl
or a
jr nz, 1$
ld b, h
ld c, l
ret
;; void putc(char c /*A*/)
_putc:
ld (0xff01), a
ld a, #0x81
ld (0xff02), a
ret
;; void puts(const char *s /*DE*/) - write until NUL (no newline)
_puts:
1$: ld a, (de)
or a
ret z
ld (0xff01), a
ld a, #0x81
ld (0xff02), a
inc de
jr 1$
;; void nl(void) - CRLF
_nl:
ld a, #0x0d
ld (0xff01), a
ld a, #0x81
ld (0xff02), a
ld a, #0x0a
ld (0xff01), a
ld a, #0x81
ld (0xff02), a
ret
;; unsigned char strlen(const char *s /*DE*/) -> A
_strlen:
ld c, #0
1$: ld a, (de)
or a
jr z, 2$
inc c
inc de
jr 1$
2$: ld a, c
ret
;; char readc(void) -> A (4 = EOF)
_readc:
ld c, #2 ; SYS_READ
rst #0x30
ret
;; void sexit(unsigned char code /*A*/) - never returns
_sexit:
ld b, a
ld c, #0 ; SYS_EXIT
rst #0x30
ret
;; unsigned char getpid(void) -> A
_getpid:
ld c, #8 ; SYS_GETPID
rst #0x30
ret
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