Misc/abrash-black-book
Watch
1
0
Fork
You've already forked abrash-black-book
 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Normal quotes

Browse source
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
Download patch file Download diff file Expand all files Collapse all files

16
26-02.md
View file

@ -6,14 +6,14 @@
; Program to illustrate operation of write mode 3 of the VGA.
; Draws 8x8 characters at arbitrary locations without disturbing
; the background, using VGA’s 8x8 ROM font. Designed
; the background, using VGA's 8x8 ROM font. Designed
; for use with modes 0Dh, 0Eh, 0Fh, 10h, and 12h.
; Runs only on VGAs (in Models 50 & up and IBM Display Adapter
; and 100% compatibles).
; Assembled with MASM
; By Michael Abrash
;
stack segment para stack ‘STACK’
stack segment para stack ‘STACK'
db 512 dup(?)
stack ends
;
@ -33,16 +33,16 @@
GC_MODE equ 5 ;GC Mode register
GC_BIT_MASK equ 8 ;GC bit mask register index
;
dseg segment para common ‘DATA’
dseg segment para common ‘DATA'
TEST_TEXT_ROW equ 69 ;row to display test text at
TEST_TEXT_COL equ 17 ;column to display test text at
TEST_TEXT_WIDTH equ 8 ;width of a character in pixels
TestString label byte
db ‘Hello, world!’,0 ;test string to print.
db ‘Hello, world!',0 ;test string to print.
FontPointer dd ? ;font offset
dseg ends
;
cseg segment para public ‘CODE’
cseg segment para public ‘CODE'
assume cs:cseg, ds:dseg
start proc near
mov ax,dseg
@ -77,7 +77,7 @@
mov di,0
mov cx,8000h ;fill all 32k words
mov ax,0ffffh ;because of set/reset, the value
; written actually doesn’t matter
; written actually doesn't matter
rep stosw ;fill with blue
;
; Set driver to use the 8x8 font.
@ -131,7 +131,7 @@
; BX = row to draw text character at
; CX = column to draw text character at
;
; Forces ALU function to “move”.
; Forces ALU function to "move".
; Forces write mode 3.
;
DrawChar proc near
@ -205,7 +205,7 @@
;
; Set up the GC rotation. In write mode 3, this is the rotation
; of CPU data before it is ANDed with the Bit Mask register to
; form the bit mask. Force the ALU function to “move”. Uses the
; form the bit mask. Force the ALU function to "move". Uses the
; readability of VGA registers to leave reserved bits unchanged.
;
mov dx,GC_INDEX