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* use SI instead of DI in the asm GetPixelX

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git-svn-id: trunk@41029 -
This commit is contained in:
nickysn 2019-01-24 13:43:34 +00:00
parent 8da6e23d0d
commit 948328160b
1 changed files with 11 additions and 11 deletions
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22
packages/graph/src/msdos/graph.pp
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@ -2495,24 +2495,24 @@ const CrtAddress: word = 0;
{$else FPC_MM_HUGE}
mov es, [SegA000]
{$endif FPC_MM_HUGE}
mov di,[Y] ; (* DI = Y coordinate *)
add di,[StartYViewPort]
mov si,[Y] ; (* SI = Y coordinate *)
add si,[StartYViewPort]
(* Multiply by 80 start *)
mov cl, 4
shl di, cl
mov bx, di
shl di, 1
shl di, 1
add di, bx ; (* Multiply Value by 80 *)
shl si, cl
mov bx, si
shl si, 1
shl si, 1
add si, bx ; (* Multiply Value by 80 *)
(* End multiply by 80 *)
mov cx, [X]
add cx, [StartXViewPort]
mov ax, cx
{DI = Y * LINESIZE, BX = X, coordinates admissible}
{SI = Y * LINESIZE, BX = X, coordinates admissible}
shr ax, 1 ; (* Faster on 286/86 machines *)
shr ax, 1
add di, ax ; {DI = Y * LINESIZE + (X SHR 2) }
add di, [VideoOfs] ; (* Pointing at start of Active page *)
add si, ax ; {SI = Y * LINESIZE + (X SHR 2) }
add si, [VideoOfs] ; (* Pointing at start of Active page *)
(* Select plane to use *)
mov dx, 03ceh
mov al, 4
@ -2520,7 +2520,7 @@ const CrtAddress: word = 0;
mov ah, cl
out dx, ax
(* End selection of plane *)
mov al, ES:[DI]
mov al, ES:[SI]
xor ah, ah
{$ifdef FPC_GRAPH_SUPPORTS_TRUECOLOR}
{ 1 byte shorter than 'xor dx, dx'; will always set dx to 0, because sign(ah)=0 }