mirror of
https://github.com/hsoft/collapseos.git
synced 2024-11-20 22:48:06 +11:00
4f7a05e3b7
It wasn't used much, so I replaced its use in the kernel with direct code and moved the routine in apps/ed, the only other place where it was used.
49 lines
791 B
NASM
49 lines
791 B
NASM
; mmap
|
|
;
|
|
; Block device that maps to memory.
|
|
;
|
|
; *** DEFINES ***
|
|
; MMAP_START: Memory address where the mmap begins
|
|
; Memory address where the mmap stops, exclusively (we aren't allowed to access
|
|
; that address).
|
|
.equ MMAP_LEN 0xffff-MMAP_START
|
|
|
|
; Returns absolute addr of memory pointer in HL if HL is within bounds.
|
|
; Sets Z on success, unset when out of bounds.
|
|
_mmapAddr:
|
|
push de
|
|
ld de, MMAP_LEN
|
|
or a ; reset carry flag
|
|
sbc hl, de
|
|
jr nc, .outOfBounds ; HL >= DE
|
|
add hl, de ; old HL value
|
|
ld de, MMAP_START
|
|
add hl, de
|
|
cp a ; ensure Z
|
|
pop de
|
|
ret
|
|
.outOfBounds:
|
|
pop de
|
|
jp unsetZ
|
|
|
|
mmapGetB:
|
|
push hl
|
|
call _mmapAddr
|
|
jr nz, .end
|
|
ld a, (hl)
|
|
; Z already set
|
|
.end:
|
|
pop hl
|
|
ret
|
|
|
|
|
|
mmapPutB:
|
|
push hl
|
|
call _mmapAddr
|
|
jr nz, .end
|
|
ld (hl), a
|
|
; Z already set
|
|
.end:
|
|
pop hl
|
|
ret
|