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Bài giảng Vi xử lý - Chương 3: Họ vi điều khiển 805 (Phần 6) - Hồ Trung Mỹ

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System & Program  
Developments of 8051  
“ Assembly Language Programming  
“ Assembler Operation  
“ Assembly Language Program Format  
“ Assemble-Time Expression Evaluation  
“ Assembler Directives  
“ Assembler Controls  
“ Linker Operation  
“ Linking Relocatable Segments and Modules  
“ Macros  
2011/12/7  
T. L. Jong, Dept. of E.E., NTHU  
1
System & Program  
Developments of 8051  
“ Program Structure and Design  
“ Introduction  
“ Advantages and Disadvantages of Structured  
Programming  
“ The Three Structures: statements, loops, choice  
“ Pseudo Code Syntax  
“ Assembly Language Programming  
“ Tools & Techniques for Program Development  
“ The Development Cycle  
“ Integration and Verification  
“ Command and Environments  
2011/12/7  
T. L. Jong, Dept. of E.E., NTHU  
2
Assembly Language  
Programming  
PROGRAM.OBJ  
PROGRAM.SRC  
LIBRARY  
ASM51  
PROGRAM.LST  
PROGRAM.ABS  
PROGRAM.MAP  
RL51  
FILE1.OBJ  
FILE2.OBJ  
2011/12/7  
T. L. Jong, Dept. of E.E., NTHU  
3
ASM(input_file) /*assemble source program in input_file)*/  
BEGIN  
/*pass 1: build the symbol table */  
lc = 0;  
/*lc=location counter; default to 0*/  
mnemonic = null;  
open input_file;  
WHILE (mnemonic != end) DO BEGIN  
get_line();  
/*get line from input_file */  
scan_line();  
/*scan line & get label/symbol & mnemonic */  
IF (label) THEN enter_into_symbol_table(label, lc);  
CASE mnemonic OF BEGIN  
null, comment, END: ; /*do nothing */  
ORG:  
EQU:  
DB:  
lc = operand_value;  
enter_in_symbol_table( symbol, operand_value);  
WHILE (got_operand) DO increment_lc;  
/* increment number of bytes defined */  
lc = lc + operand_value;  
DS:  
1_byte_instruction:  
2_byte_instruction:  
3_byte_instruction:  
lc = lc + 1;  
lc = lc + 2;  
lc = lc + 3;  
END  
END  
2011/12/7  
T. L. Jong, Dept. of E.E., NTHU  
4
/*pass 2: create the object program*/  
rewind_input_file_pointer;  
lc = 0;  
mnemonic = null;  
open_output_file;  
WHILE (mnemonic != end) DO BEGIN  
get_line();  
scan_line(); /* determine mnemonic op code and value(s) of operand(s)*/  
/*Note: if symbols are used in operand field, their values are looked-up*/  
/* in the symbol table created during pass 1  
CASE mnemonic OF BEGIN  
*/  
null, comment, EQU, END: ;  
/*do nothing */  
ORG:  
lc = operand_value;  
DB: WHILE (operand) DO BEGIN  
put_in_objectfile(operand);  
lc = lc + 1;  
END  
/* increment number of bytes defined */  
2011/12/7  
T. L. Jong, Dept. of E.E., NTHU  
5
DS: lc = lc + operand;  
1_byte_instruction:  
2_byte_instruction:  
put_in_objectfile(inst_code);  
put_in_objectfile(inst_code);  
put_in_objectfile(operand);  
3_byte_instruction:  
put_in_objectfile(inst_code);  
put_in_objectfile(operand high-byte);  
put_in_objectfile(operand low-byte);  
lc = lc + size_of_instruction;  
END  
END  
close_input_file;  
close_output_file;  
END  
2011/12/7  
T. L. Jong, Dept. of E.E., NTHU  
6
Assembly Language  
Program Format  
“Assembly language program contains:  
“ Machine instructions (ANL, MOV)  
“ Assembler directives (ORG,..)  
“ Assembler controls ($TITLE)  
“ Comments  
“Lines of machine instructions or  
assembler directives:  
[label:] Mnemonic [operand] [,operand] […] [;comment]  
2011/12/7  
T. L. Jong, Dept. of E.E., NTHU  
7
Assembly Language  
Program Format  
“Label & symbol  
PAR EQU 500  
;PAR is a symbol  
; which represents the  
; value 500  
START: MOV A,#0FFH ;START is a label  
;which represents the  
;address of the MOV  
;instruction  
“ Special Assembler Symbols  
“ A, R0-R7, DPTR, PC, C, AB, $  
2011/12/7  
T. L. Jong, Dept. of E.E., NTHU  
8
Assemble-Time Expression  
Evaluation  
“ MOV A,#10 + 10H (MOV A,#1AH)  
“ MOV A,#25 MOD 7 (MOV A,#4)  
“ MOV A,#’9’ AND 0FH (MOV A,#9)  
“ THREE  
EQU 3  
Minus_three EQU -3  
MOV  
MOV  
MOV  
A,#(NOT THREE)+1  
A,#Minus_three  
A,#11111101B  
“ MOV A,#8 SHL 1 (MOV A,#10H)  
“ MOV A,#HIGH 1234H (MOV A,12H)  
2011/12/7  
T. L. Jong, Dept. of E.E., NTHU  
9
Assemble-Time Expression  
Evaluation  
“ Relational operators: result is always false  
(0000H) or true (FFFFH)  
EQ  
=
equal  
NE  
LT  
<>  
<
not equal  
less than  
LE  
GT  
GE  
<=  
>
>=  
less than or equal to  
greater than  
greater than or equal to  
MOV  
MOV  
MOV  
MOV  
MOV  
A,#5 = 5  
A,#’X’ LT ‘Z’  
A,#5 NE 4  
A,#’X’ >= ‘X’  
A,#$ > 0  
2011/12/7  
T. L. Jong, Dept. of E.E., NTHU  
10  
Assemble-Time Expression  
Evaluation  
“ Expression Examples:  
‘B’ - ‘A’ 0001H  
‘A’ SHL 8  
4100H  
8/3  
155 MOD 2 0001H  
4*4 0010H  
8 AND 7 0000H  
NOT 1 FFFEH  
0002H  
LOW 65535 00FFH  
(8 + 1)*2  
5 EQ 4  
0012H  
0000H  
FFFFH  
FFFFH  
‘A’ LT ‘B’  
3 <= 3  
2011/12/7  
T. L. Jong, Dept. of E.E., NTHU  
11  
Assemble-Time Expression  
Evaluation  
“ Operator Precedence  
( )  
HIGH LOW  
* / MOD SHL SHR  
+ -  
EQ NE LT LE GT GE = <> < <= > >=  
NOT  
AND  
OR XOR  
“ When same precedence, operators are evaluated  
left-to-right  
HIGH (‘A’ SHL 8) 0041H  
HIGH ‘A’ SHL 8 0000H  
NOT ‘A’ - 1  
FFBFH  
‘A’ OR ‘A’ SHL 8 4141H  
2011/12/7  
T. L. Jong, Dept. of E.E., NTHU  
12  
Assembler Directives  
“ Assembler state control (ORG, END, USING)  
“ Symbol definition (SEGMENT, EQU, SET,  
DATA, IDATA, XDATA, BIT, CODE)  
“ Storage initialization/reservation (DS, DB,  
DW, DBIT)  
“ Program linkage (PUBLIC, EXTRN, NAME)  
“ Segment selection (RSEG, CSEG, DSEG,  
ISEG, BSEG, XSEG)  
2011/12/7  
T. L. Jong, Dept. of E.E., NTHU  
13  
Assembler State Controls  
“ ORG, END, USING  
ORG  
ORG  
100H  
($ + 1000H) AND 0F000H  
;set to next  
;4k boundary  
END  
;should be the last statement in the source file  
USING  
expression  
;inform ASM51 of the currently  
;active register bank  
MOV  
PSW,#00011000B  
;select RB 3, the only way  
;to switch register banks  
USING  
PUSH  
MOV  
USING  
PUSH  
3
;use register bank 3  
AR7 ;1FH (R7 in bank 3)  
PSW,#00001000B  
1
AR7 ;0FH  
2011/12/7  
T. L. Jong, Dept. of E.E., NTHU  
14  
Symbol Definition  
“The symbol definition directive creates  
symbols representing segments,  
registers, numbers, & addresses.  
2011/12/7  
T. L. Jong, Dept. of E.E., NTHU  
15  
Symbol Definition  
“ Segment (CODE, XDATA, DATA,IDATA,BIT)  
symbol SEGMENT segment_type  
CODE (code segment)  
DATA (the internal data space accessible by direct  
addressing 00-7FH)  
IDATA (the entire internal data space accessible by  
indirect addressing, 00-7FH on 8051, 00-FFH on  
8052)  
XDATA (the external data space)  
BIT (the bit space; overlapping byte locations 20H-  
2FH of the internal data space)  
EPROM SEGMENT CODE (declares that EPROM is  
a code segment. To actually begin using this  
segment, the RSEG directive is used)  
2011/12/7  
T. L. Jong, Dept. of E.E., NTHU  
16  
Symbol Definition  
“ EQU and SET -- numbers  
symbol EQU expression (assigns a numeric  
value to a specific symbol name)  
N27  
HERE  
EQU 27  
EQU $  
MESSAGE: DB ‘This is a message’  
LENGTH EQU $-MESSAGE  
symbol SET expression (similar to EQU except  
that symbol can be redefined  
later using another SET directive)  
2011/12/7  
T. L. Jong, Dept. of E.E., NTHU  
17  
Symbol Definition  
“ DATA, IDATA, XDATA, BIT, & CODE: assign  
addresses of the corresponding segment  
type to a symbol.  
“ e.g.,  
FLAG1  
FLAG2  
EQU  
BIT  
05H  
05H  
SETB  
SETB  
MOV  
MOV  
FLAG1  
FLAG2  
FLAG1,#0  
FLAG2,#0  
(error message: data segment address expected)  
2011/12/7  
T. L. Jong, Dept. of E.E., NTHU  
18  
Storage  
Initialization/Reservation  
“ DS (define storage)  
[label:]  
DS  
expression (reserves spaces in byte units,  
can be used in any segment type  
except BIT)  
DSEG AT 30H  
;put in data segment  
;(absolute , internal)  
LENGTH EQU 40  
BUFFER: DS LENGTH  
;reserve 40 bytes  
MOV R7,#LENGTH  
MOV R0,#BUFFER ;R0=30H  
MOV @R0,#0  
LOOP:  
INC  
R0  
DJNZ R7,LOOP  
2011/12/7  
T. L. Jong, Dept. of E.E., NTHU  
19  
Storage  
Initialization/Reservation  
“ Create 1000 bytes in external RAM at 4000H  
XSTART EQU 4000H  
XLENGTH EQU 1000  
XSEG AT XSTART ;put I data segment  
;(absolute , internal)  
XBUFFER: DS  
XLENGTH  
;reserve 40 bytes  
MOV DPTR,#XBUFFER  
LOOP:  
CLR A  
MOV @DPTR,A  
INC  
DPTR  
MOV A,DPL  
CJNE A,#LOW(XBUFFER + XLENGTH + 1),LOOP  
MOV A,DPH  
CJNE A,#HIGH(XBUFFER + XLENGTH + 1),LOOP  
(continue)  
2011/12/7  
T. L. Jong, Dept. of E.E., NTHU  
20  
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