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This commit is contained in:
James Gregory 2013-12-30 18:34:31 +11:00
commit 18011c595a
352 changed files with 6040 additions and 6040 deletions
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41-03.md
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@ -4,7 +4,7 @@
**LISTING 41.3 L41-3.ASM**
; Draws all pixels in list of horizontal lines passed in, in mode 13h, VGA’s
; Draws all pixels in list of horizontal lines passed in, in mode 13h, VGA's
; 320x200 256-color mode. Uses REP STOS to fill each line.
; ******************************************************************
; NOTE: is able to reverse the X coords for a scan line, if necessary, to make
@ -40,9 +40,9 @@
public _DrawHorizontalLineList
align 2
_DrawHorizontalLineList proc
push bp ;preserve caller’s stack frame
push bp ;preserve caller's stack frame
mov bp,sp ;point to our stack frame
push si ;preserve caller’s register variables
push si ;preserve caller's register variables
push di
cld ;make string instructions inc pointers
@ -57,14 +57,14 @@
; for the first (top) horizontal line
mov si,[si+Lngth] ;# of scan lines to draw
and si,si ;are there any lines to draw?
jz FillDone ;no, so we’re done
jz FillDone ;no, so we're done
mov al,byte ptr [bp+Color] ;color with which to fill
mov ah,al ;duplicate color for STOSW
FillLoop:
mov di,[bx+XStart] ;left edge of fill on this line
mov cx,[bx+XEnd] ;right edge of fill
cmp di,cx ;is XStart > XEnd?
jle NoSwap ;no, we’re all set
jle NoSwap ;no, we're all set
xchg di,cx ;yes, so swap edges
NoSwap:
sub cx,di ;width of fill on this line
@ -79,7 +79,7 @@
MainFill:
shr cx,1 ;# of words in fill
rep stosw ;fill as many words as possible
adc cx,cx ;1 if there’s an odd trailing byte to
adc cx,cx ;1 if there's an odd trailing byte to
; do, 0 otherwise
rep stosb ;fill any odd trailing byte
LineFillDone:
@ -88,17 +88,17 @@
dec si ;count off lines to fill
jnz FillLoop
FillDone:
pop di ;restore caller’s register variables
pop di ;restore caller's register variables
pop si
pop bp ;restore caller’s stack frame
pop bp ;restore caller's stack frame
ret
_DrawHorizontalLineList endp
end
Listing 41.4 is almost identical to Listing 40.1 from Chapter 40. I’ve
Listing 41.4 is almost identical to Listing 40.1 from Chapter 40. I've
modified Listing 40.1 to employ the vertical-monotone detection test
we’ve been talking about and use the fast vertical-monotone drawing code
whenever possible; that’s what Listing 41.4 is. Note well that Listing
we've been talking about and use the fast vertical-monotone drawing code
whenever possible; that's what Listing 41.4 is. Note well that Listing
40.5 from Chapter 40 is also required in order for this code to link.
Listing 41.5 is an appropriately updated version of the POLYGON.H header
file.