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[Reverse-engineering] [th03/mainl] CDG line removal for upwards motion 

Not *really* CDG-related, but it does use CDG slot data, and is easy
enough to be covered right now…

Funded by DTM.
This commit is contained in:
nmlgc 2018-10-16 00:08:04 +02:00
parent 766a34d044
commit 01a430d027
2 changed files with 73 additions and 71 deletions
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68
th03/formats/cdg_unput_for_upwards_motion.asm Normal file
View File

@ -0,0 +1,68 @@
; Assuming that the CDG image in the given [slot] was previously displayed
; centered at (⌊x_center/8⌋*8, y_center), this function clears the two lines
; at the bottom of that image, as well as the one line immediately below, from
; the VRAM's E plane.
; void cdg_unput_for_upwards_motion_e(int x, int y, int slot);
public _cdg_unput_for_upwards_motion_e
_cdg_unput_for_upwards_motion_e proc near
@@h = word ptr -4
@@w = word ptr -2
@@slot = word ptr 4
@@y_center = word ptr 6
@@x_center = word ptr 8
enter 4, 0
push si
push di
mov bx, [bp+@@slot]
shl bx, 4
mov ax, _cdg_slots.pixel_width[bx]
mov [bp+@@w], ax
mov bx, [bp+@@slot]
shl bx, 4
mov ax, _cdg_slots.pixel_height[bx]
mov [bp+@@h], ax
mov ax, [bp+@@w]
cwd
sub ax, dx
sar ax, 1
sub [bp+@@x_center], ax
mov ax, [bp+@@h]
cwd
sub ax, dx
sar ax, 1
add ax, -2
add [bp+@@y_center], ax
mov ax, [bp+@@x_center]
sar ax, 3
mov dx, [bp+@@y_center]
shl dx, 6
add ax, dx
mov dx, [bp+@@y_center]
shl dx, 4
add ax, dx
mov di, ax
mov ax, 0E000h
mov es, ax
assume es:nothing
mov dx, [bp+@@w]
shr dx, 4
mov si, (640 / 8)
sub si, dx
sub si, dx
xor ax, ax
mov cx, dx
rep stosw
add di, si
mov cx, dx
rep stosw
add di, si
mov cx, dx
rep stosw
pop di
pop si
leave
retn 6
_cdg_unput_for_upwards_motion_e endp

76
th03_mainl.asm
View File

@ -4506,73 +4506,7 @@ loc_BAC0:
retn 6
sub_BA8A endp
; =============== S U B R O U T I N E =======================================
; Attributes: bp-based frame
sub_BAD6 proc near
var_4 = word ptr -4
var_2 = word ptr -2
arg_0 = word ptr 4
arg_2 = word ptr 6
arg_4 = word ptr 8
enter 4, 0
push si
push di
mov bx, [bp+arg_0]
shl bx, 4
mov ax, [bx+1D10h]
mov [bp+var_2], ax
mov bx, [bp+arg_0]
shl bx, 4
mov ax, [bx+1D12h]
mov [bp+var_4], ax
mov ax, [bp+var_2]
cwd
sub ax, dx
sar ax, 1
sub [bp+arg_4], ax
mov ax, [bp+var_4]
cwd
sub ax, dx
sar ax, 1
add ax, 0FFFEh
add [bp+arg_2], ax
mov ax, [bp+arg_4]
sar ax, 3
mov dx, [bp+arg_2]
shl dx, 6
add ax, dx
mov dx, [bp+arg_2]
shl dx, 4
add ax, dx
mov di, ax
mov ax, 0E000h
mov es, ax
assume es:nothing
mov dx, [bp+var_2]
shr dx, 4
mov si, 50h ; 'P'
sub si, dx
sub si, dx
xor ax, ax
mov cx, dx
rep stosw
add di, si
mov cx, dx
rep stosw
add di, si
mov cx, dx
rep stosw
pop di
pop si
leave
retn 6
sub_BAD6 endp
include th03/formats/cdg_unput_for_upwards_motion.asm
; =============== S U B R O U T I N E =======================================
@ -4901,7 +4835,7 @@ arg_0 = word ptr 4
mov bx, ax
push word ptr [bx+27D8h]
push di
call sub_BAD6
call _cdg_unput_for_upwards_motion_e
mov al, byte_10BB4
mov ah, 0
add ax, ax
@ -5004,7 +4938,7 @@ arg_0 = word ptr 4
mov bx, ax
push word ptr [bx+27D8h]
push di
call sub_BAD6
call _cdg_unput_for_upwards_motion_e
mov al, byte_10BB4
mov ah, 0
add ax, ax
@ -5250,11 +5184,11 @@ loc_C0DC:
loc_C114:
cmp word_10BB2, 0A1h
jg short loc_C12A
push 140h
push 320
push word_10BC2
lea ax, [si-1]
push ax
call sub_BAD6
call _cdg_unput_for_upwards_motion_e
loc_C12A:
push si