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online asm in c51, what is the matter?

11 22

I use this code:

#include <reg52.h>

void main(void)
{
  unsigned char data x8,x9,x10;
  while(1)
  {
  x8 = 0;
  x9 = 9;
  x10 = x8 + x9;
  __asm CLR A;
  }
}

and the SRC file is look like this, I think this is right:
; void main(void)

	RSEG  ?PR?main?MAIN
main:
	USING	0
			; SOURCE LINE # 5
; {
			; SOURCE LINE # 6
?C0001:
;   unsigned char data x8,x9,x10;
;   while(1)
			; SOURCE LINE # 8
;   {
			; SOURCE LINE # 9
;   x8 = 0;
			; SOURCE LINE # 10
;---- Variable 'x8?040' assigned to Register 'R7' ----
	CLR  	A
	MOV  	R7,A
;   x9 = 9;
			; SOURCE LINE # 11
;---- Variable 'x9?041' assigned to Register 'R6' ----
	MOV  	R6,#09H
;   x10 = x8 + x9;
			; SOURCE LINE # 12
	ADD  	A,R6
	MOV  	x10?042,A
;   __asm CLR A;
	 CLR A;
;   }
			; SOURCE LINE # 14
	SJMP 	?C0001
	RET  	
; END OF main

	END

But, when Debug it, it look like this in debug window:
C_STARTUP:
C:0x0000    020003   LJMP     STARTUP1(C:0003)
STARTUP1:
C:0x0003    787F     MOV      R0,#0x7F
C:0x0005    E4       CLR      A
IDATALOOP:
C:0x0006    F6       MOV      @R0,A
C:0x0007    D8FD     DJNZ     R0,IDATALOOP(C:0006)
C:0x0009    758108   MOV      SP(0x81),#0x08
C:0x000C    020000   LJMP     C_STARTUP(C:0000)========>You see here!!!
MAIN:
C:0x000F    E4       CLR      A
C:0x0010    FF       MOV      R7,A
C:0x0011    7E09     MOV      R6,#0x09
C:0x0013    2E       ADD      A,R6
C:0x0014    F508     MOV      0x08,A
C:0x0016    E4       CLR      A
C:0x0017    80F6     SJMP     MAIN(C:000F)
C:0x0019    22       RET

do you know why?

Parents
  • 0

    1. I Create a new project, then add the main.c, right click the main.c, select the "options for file main.c", enables the two options "Generate Assembler SRC File and Assemble SRC File", Build it, and I get that questions.

    2.Now, I try a new method, only use
    #pragma src at the first line in the main.c, then debug it, and I get this result, I think this one is right:

    C:0x0000    020003   LJMP     C:0003
C:0x0003    787F     MOV      R0,#0x7F
C:0x0005    E4       CLR      A
C:0x0006    F6       MOV      @R0,A
C:0x0007    D8FD     DJNZ     R0,C:0006
C:0x0009    758108   MOV      SP(0x81),#0x08
C:0x000C    02000F   LJMP     main(C:000F)
5: void main(void)
6: {
7:   unsigned char data x8,x9,x10;
8:   while(1)
9:   {
10:     x8 = 0;
C:0x000F    E4       CLR      A
C:0x0010    FF       MOV      R7,A
11:     x9 = 9;
C:0x0011    7E09     MOV      R6,#0x09
12:     x10 = x8 + x9;
13:     __asm CLR A;
C:0x0013    2E       ADD      A,R6
C:0x0014    F508     MOV      0x08,A
14:   }
C:0x0016    80F7     SJMP     main(C:000F)

    3.But why?

Reply
  • 0

    1. I Create a new project, then add the main.c, right click the main.c, select the "options for file main.c", enables the two options "Generate Assembler SRC File and Assemble SRC File", Build it, and I get that questions.

    2.Now, I try a new method, only use
    #pragma src at the first line in the main.c, then debug it, and I get this result, I think this one is right:

    C:0x0000    020003   LJMP     C:0003
C:0x0003    787F     MOV      R0,#0x7F
C:0x0005    E4       CLR      A
C:0x0006    F6       MOV      @R0,A
C:0x0007    D8FD     DJNZ     R0,C:0006
C:0x0009    758108   MOV      SP(0x81),#0x08
C:0x000C    02000F   LJMP     main(C:000F)
5: void main(void)
6: {
7:   unsigned char data x8,x9,x10;
8:   while(1)
9:   {
10:     x8 = 0;
C:0x000F    E4       CLR      A
C:0x0010    FF       MOV      R7,A
11:     x9 = 9;
C:0x0011    7E09     MOV      R6,#0x09
12:     x10 = x8 + x9;
13:     __asm CLR A;
C:0x0013    2E       ADD      A,R6
C:0x0014    F508     MOV      0x08,A
14:   }
C:0x0016    80F7     SJMP     main(C:000F)

    3.But why?

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