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* replaced the slow mul instruction in GetPixel16 with faster shifts and adds

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git-svn-id: trunk@40987 -
This commit is contained in:
nickysn 2019-01-22 14:27:48 +00:00
parent 985ec0688a
commit 6753237fe4
1 changed files with 8 additions and 6 deletions
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14
packages/graph/src/msdos/graph.pp
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@ -1678,14 +1678,17 @@ end;
mov di, ax
mov cl, 3
shr ax, cl
xchg ax, cx
mov ax, 80
mov bx, [Y]
add bx, [StartYViewPort]
mul bx
add ax,cx
mov si,ax { SI = correct offset into video segment }
inc cx { CL=4 }
shl bx, cl { BX=16*(Y+StartYViewPort)*16 }
mov si, bx { SI=16*(Y+StartYViewPort)*16 }
shl si, 1 { SI=32*(Y+StartYViewPort)*32 }
shl si, 1 { SI=64*(Y+StartYViewPort)*64 }
add si, bx { SI=(64+16)*(Y+StartYViewPort)=80*(Y+StartYViewPort) }
add si, ax { SI=correct offset into video segment }
add si, [VideoOfs] { Point to correct page offset... }
{$ifdef FPC_MM_HUGE}
mov ax, SEG SegA000
@ -1694,7 +1697,6 @@ end;
{$else FPC_MM_HUGE}
mov es, [SegA000]
{$endif FPC_MM_HUGE}
add si,[VideoOfs] { Point to correct page offset... }
mov dx,03ceh
mov ax,0304h