falso
/
z80
mirror of https://github.com/falsovsky/z80.git
1
0
Fork 0
Code Issues Releases Wiki Activity

Routine to print correctly on X

This commit is contained in:
Pedro de Oliveira 2014-08-19 07:10:30 +01:00
parent a81933f16b
commit 0d95f0183c
1 changed files with 31 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

38
starfield/main.asm
View File

@ -38,11 +38,7 @@ main
push hl push hl
call get_screen_address call get_screen_address
ld b, a call write_pixel
ld a, (hl)
;set b, a
or b
ld (hl), a
pop hl pop hl
inc hl inc hl
@ -52,8 +48,36 @@ main
pop bc pop bc
ret ret
PROC PROC
; Calculate the high byte of the screen addressand store in H reg. tbl_origin db $0, $1, $2, $3, $4, $5, $6, $7
tbl_dest db 128, 64, 32, 16, 8, 4, 2, 1
write_pixel
push hl
ld de, tbl_origin
ld hl, tbl_dest
lookup_table_loop
ld b, a
ld a, (de)
cp b
jr z, lookup_table_found
inc de
inc hl
ld a, b
jr lookup_table_loop
lookup_table_found
ld a, (hl)
ld b, a
pop hl
ld a, (hl)
or b
ld (hl), a
ret
ENDP
PROC
; Calculate the high byte of the screen address and store in H reg.
; On Entry: D reg = X coord, E reg = Y coord ; On Entry: D reg = X coord, E reg = Y coord
; On Exit: HL = screen address, A = pixel postion ; On Exit: HL = screen address, A = pixel postion
get_screen_address get_screen_address
@ -81,7 +105,7 @@ get_screen_address
and %11100000 and %11100000
or l or l
ld l,a ld l,a
; Calculate pixel postion and store in A reg. ; Calculate pixel position and store in A reg.
ld a,d ld a,d
and %00000111 and %00000111
ret ret