Wang Shuang "assembly Language" (third edition) Experiment 9 analysis

Brief introduction

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Code

Assume cs:codedata segment db ' Welcome to masm! ' DB 02h,24h,71h; Required three colors corresponding to 16 binary code data endsstack segment db (0); can also be the following definition method:; DW 8 DUP (0) stack endscode segmentstart:; Sets the data segment, and DS:BX points to the first cell of the data segment;        That is, the content of DS:[BX] is the content of the first cell of the data segment MOV Ax,data mov ds,ax; Set the display buffer segment MOV ax,0b800h; set the start cache MOV es,ax; set the stack segment MOV ax,stack mov ss,ax mov sp,10h; point to the top of the stack; initial A three register mov bx,780h; Line from 12-14 lines (note: Counting starting from line 1th) MOV si,10h; The offset of the color, three cycles each time; Add 1h point to the next color mov cx,3; Three cycles change line S:mov ah,ds:[si]; color beforehand stored in AH in the push CX push SI mov cx,16; 16 Cycles change the column MOV si,64; The meaning of the SI here is how many columns; Why start with the 64 column?; (1) string is 32 bytes, 16 bytes ascll code, 16 byte attribute;    (2) Each row has 160 columns, then the remaining 160-32=128 are blank;   To make the string centered, the left and right side of the string are displayed;        should be 64 bytes (128/2), and the number of columns is counted from 0,    ; So the 64 bytes on the left is 0-63, so here the offset is a. mov di,0 S0:mov al,ds:[di]; Converts the characters in a date field to an incoming ES in MOV es:[ Bx+si],al; Low store character mov Es:[bx+si+1],ah;                High storage color add si,2; display buffer character ASCII offset of 2 add di,1;d ATA segment character offset, each with 1 loop s0        Pop si pop cx, LIFO, first out stack si, then stack cx add si,1h; point to Next color add bx,0a0h; point to Next line 160=0a0h Loop s mov ax,4c00h int 21hcode endsend start

Results

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Wang Shuang "assembly Language" (third edition) Experiment 9 analysis