Misc/abrash-black-book
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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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24-02.md
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@ -4,14 +4,14 @@
**LISTING 24.1 L24-1.ASM**
; Program to illustrate operation of ALUs and latches of the VGA’s
; Program to illustrate operation of ALUs and latches of the VGA's
; Graphics Controller. Draws a variety of patterns against
; a horizontally striped background, using each of the 4 available
; logical functions (data unmodified, AND, OR, XOR) in turn to combine
; the images with the background.
; By Michael Abrash.
;
stack segment para stack ‘STACK’
stack segment para stack ‘STACK'
db 512 dup(?)
stack ends
;
@ -34,23 +34,23 @@
; register index
GC_MODE equ 5 ;GC mode register index
;
dseg segment para common ‘DATA’
dseg segment para common ‘DATA'
;
; String used to label logical functions.
;
LabelString label byte
db ‘UNMODIFIED AND OR XOR ’
db ‘UNMODIFIED AND OR XOR '
LABEL_STRING_LENGTH equ $-LabelString
;
; Strings used to label fill patterns.
;
FillPatternFF db ‘Fill Pattern: 0FFh’
FillPatternFF db ‘Fill Pattern: 0FFh'
FILL_PATTERN_FF_LENGTH equ $ - FillPatternFF
FillPattern00 db ‘Fill Pattern: 000h’
FillPattern00 db ‘Fill Pattern: 000h'
FILL_PATTERN_00_LENGTH equ $ - FillPattern00
FillPatternVert db ‘Fill Pattern: Vertical Bar’
FillPatternVert db ‘Fill Pattern: Vertical Bar'
FILL_PATTERN_VERT_LENGTH equ $ - FillPatternVert
FillPatternHorz db ‘Fill Pattern: Horizontal Bar’
FillPatternHorz db ‘Fill Pattern: Horizontal Bar'
FILL_PATTERN_HORZ_LENGTH equ $ - FillPatternHorz
;
dseg ends
@ -77,7 +77,7 @@
int 10h
endm
;
cseg segment para public ‘CODE’
cseg segment para public ‘CODE'
assume cs:cseg, ds:dseg
start proc near
mov ax,dseg
@ -139,15 +139,15 @@
; Label the screen.
;
push ds
pop es ;strings we’ll display are passed to BIOS
pop es ;strings we'll display are passed to BIOS
; by pointing ES:BP to them
;
; Label the logical functions, using the VGA BIOS’s
; Label the logical functions, using the VGA BIOS's
; write string function.
;
TEXT_UP LabelString, LABEL_STRING_LENGTH, 24, 0
;
; Label the fill patterns, using the VGA BIOS’s
; Label the fill patterns, using the VGA BIOS's
; write string function.
;
TEXT_UP FillPatternFF, FILL_PATTERN_FF_LENGTH, 3, 42
@ -155,7 +155,7 @@
TEXT_UP FillPatternVert, FILL_PATTERN_VERT_LENGTH, 15, 42
TEXT_UP FillPatternHorz, FILL_PATTERN_HORZ_LENGTH, 21, 42
;
; Wait until a key’s been hit to reset screen mode & exit.
; Wait until a key's been hit to reset screen mode & exit.
;
WaitForKey:
mov ah,1
@ -195,7 +195,7 @@
mov cx,WIDTH
ColumnLoop:
mov ah,es:[di] ;load display memory contents into
; GC latches (we don’t actually care
; GC latches (we don't actually care
; about value read into AH)
stosb ;write pattern, which is logically
; combined with latch contents for each
@ -225,7 +225,7 @@
dec ax ;0ffh fill (smaller to do word than byte DEC)
mov cx,si ;width to fill
HBLoop1:
mov bl,es:[di] ;load latches (don’t care about value)
mov bl,es:[di] ;load latches (don't care about value)
stosb ;write solid pattern, through ALUs
loop HBLoop1
add di,SCREEN_WIDTH_IN_BYTES - VERTICAL_BOX_WIDTH_IN_BYTES