MSP430 Kopierfunktion (Flash in RAM)

In diesem Beispiel-Programm wird eine einfache Kopierfunktion in C und ASM geschrieben. Die Funktion/Unterprogramm soll Daten aus dem Flash in den RAM kopieren bis ein bestimmtes Zeichen bzw. ein bestimmter Wert gefunden wurde (in diesem Beispiel wird ein String kopiert bis das Stringende-Zeichen gefunden wurde). Sind die Daten für den reservierten Buffer zu groß, wird eine 0 zurückgegeben, bei einem erfolgreichen Kopiervorgang eine 1.

ASM-Programm

FILE: main.asm

;***********************************************
;     ___       _             _     
;    |   |_ _ _| |___ ___   _| |___
;    | | |_'_| . | -_|  _|_| . | -_|
;    |___|_,_|___|___|___|_|___|___|
;
; FILE:     main.asm
; Author:   declis (xdec.de)
;***********************************************

    .cdecls "msp430g2231.h"
    .cdecls "lib_func.h"
    .bss buffer,size               ;allocate 16 bytes in RAM
    .sect .const
data: .cstring "omg ASM rox kthx"  ;define string with '�' (in flash)
    .ref copy_data_ram
    .global main
    .text

main:
    mov.w #0x280,SP                ;initialize stack pointer
    mov.w #WDTPW+WDTHOLD,&WDTCTL   ;stop watchdog timer

    mov.w #data,R4                 ;sourcepointer for data in R4
    mov.w #buffer,R5               ;sourcepointer for buffer in R5

    call #copy_data_ram

    jmp $

    .end

FILE: lib_func.asm

;***********************************************
;     ___       _             _     
;    |   |_ _ _| |___ ___   _| |___
;    | | |_'_| . | -_|  _|_| . | -_|
;    |___|_,_|___|___|___|_|___|___|
;
; FILE:     lib_func.asm
; Author:   declis (xdec.de)
;***********************************************

    .cdecls "msp430g2231.h"
    .cdecls "lib_func.h"
    .def copy_data_ram         ;global entry of function
    .text

;------------------------------------------
; Name:         copy_data_ram
; Description:  copy data into RAM/Buffer till
;               termination value found
; Input:        R4 - sourcepointer of source
;               R5 - sourcepointer of buffer
; Returns:      R8 - 1 = success, 0 = overflow
; Destroys:     R8
;------------------------------------------
copy_data_ram:
    push.w SR
    push.w R4
    push.w R5
    push.w R6

    mov.w #size,R8         ;copy size into R8
    mov.w #0,R6            ;index=0
loop:
    cmp.b #value,0(R4)     ;termination value found?
    jz success

    cmp.w R8,R6            ;overflow?
    jz over_error

    mov.b @R4+,0(R5)       ;copy value of "source" into buffer and increment
                            ;sourcepointer of "source"
                            ;C: buffer[index]=source[index]; index++;
    inc.w R5               ;increment sourcepointer of "buffer"
    inc.w R6               ;increment index
    jmp loop

over_error:
    mov.w #0,R8            ;return 0
    jmp done

success:
    mov.w #1,R8            ;return 1

done:
    pop.w R6
    pop.w R5
    pop.w R4
    pop.w SR
    ret

    .end

FILE: lib_func.h

/*************************************************
 *     ___       _             _     
 *    |   |_ _ _| |___ ___   _| |___
 *    | | |_'_| . | -_|  _|_| . | -_|
 *    |___|_,_|___|___|___|_|___|___|
 *
 * FILE:     lib_func.h
 * Author:   declis (xdec.de)
 ************************************************/

#ifndef LIB_FUNC_H_
#define LIB_FUNC_H_

#define size 16         /* define size=16 */
#define value 0         /* define termination value */

#endif /*LIB_FUNC_H_*/

C-Programm

FILE: main.c

  1. /*************************************************
  2.  *     ___       _             _    
  3.  *    |   |_ _ _| |___ ___   _| |___
  4.  *    | | |_'_| . | -_|  _|_| . | -_|
  5.  *    |___|_,_|___|___|___|_|___|___|
  6.  *
  7.  * FILE:     main.c
  8.  * Author:   declis (xdec.de)
  9.  ************************************************/
  10.  
  11. #include <msp430g2231.h>
  12. #include "lib_func_c.h"
  13.  
  14. void main(void)
  15. {
  16.     const char data[]={"omg ASM rox kthx"}; /* data in flash (const char) */
  17.     char buffer[size];                      /* allocate 16 bytes in RAM */
  18.  
  19.     WDTCTL=WDTPW+WDTHOLD;                   /* stop watchdog timer */
  20.  
  21.     copy_data_ram(data,buffer);
  22.  
  23.     for(;;);
  24. }
/*************************************************
 *     ___       _             _     
 *    |   |_ _ _| |___ ___   _| |___
 *    | | |_'_| . | -_|  _|_| . | -_|
 *    |___|_,_|___|___|___|_|___|___|
 *
 * FILE:     main.c
 * Author:   declis (xdec.de)
 ************************************************/

#include <msp430g2231.h>
#include "lib_func_c.h"

void main(void)
{
    const char data[]={"omg ASM rox kthx"}; /* data in flash (const char) */
    char buffer[size];                      /* allocate 16 bytes in RAM */

    WDTCTL=WDTPW+WDTHOLD;                   /* stop watchdog timer */

    copy_data_ram(data,buffer);

    for(;;);
}

FILE: lib_func.c

  1. /*************************************************
  2.  *     ___       _             _    
  3.  *    |   |_ _ _| |___ ___   _| |___
  4.  *    | | |_'_| . | -_|  _|_| . | -_|
  5.  *    |___|_,_|___|___|___|_|___|___|
  6.  *
  7.  * FILE:     lib_func.c
  8.  * Author:   declis (xdec.de)
  9.  ************************************************/
  10.  
  11. #include <msp430g2231.h>
  12. #include "lib_func_c.h"
  13.  
  14. char copy_data_ram(const char *data,char *buffer)
  15. {
  16.     char index=0;
  17.  
  18.     for(;data[index]!=value;index++)    /* termination value found? */
  19.     {
  20.         if(index==size) return 0;       /* overflow occurred */
  21.         buffer[index]=data[index];      /* copy flash-data in RAM/Buffer */
  22.     }
  23.  
  24.     return 1;                           /* success */
  25. }
/*************************************************
 *     ___       _             _     
 *    |   |_ _ _| |___ ___   _| |___
 *    | | |_'_| . | -_|  _|_| . | -_|
 *    |___|_,_|___|___|___|_|___|___|
 *
 * FILE:     lib_func.c
 * Author:   declis (xdec.de)
 ************************************************/

#include <msp430g2231.h>
#include "lib_func_c.h"

char copy_data_ram(const char *data,char *buffer)
{
    char index=0;

    for(;data[index]!=value;index++)    /* termination value found? */
    {
        if(index==size) return 0;       /* overflow occurred */
        buffer[index]=data[index];      /* copy flash-data in RAM/Buffer */
    }

    return 1;                           /* success */
}

FILE: lib_func_c.h

  1. /*************************************************
  2.  *     ___       _             _    
  3.  *    |   |_ _ _| |___ ___   _| |___
  4.  *    | | |_'_| . | -_|  _|_| . | -_|
  5.  *    |___|_,_|___|___|___|_|___|___|
  6.  *
  7.  * FILE:     lib_func_c.h
  8.  * Author:   declis (xdec.de)
  9.  ************************************************/
  10.  
  11. #ifndef LIB_FUNC_C_H_
  12. #define LIB_FUNC_C_H_
  13.  
  14. #define size 16         /* define size=16 */
  15. #define value 0         /* define termination value */
  16.  
  17. char copy_data_ram(const char*,char*);
  18.  
  19. #endif /*LIB_FUNC_C_H_*/
/*************************************************
 *     ___       _             _     
 *    |   |_ _ _| |___ ___   _| |___
 *    | | |_'_| . | -_|  _|_| . | -_|
 *    |___|_,_|___|___|___|_|___|___|
 *
 * FILE:     lib_func_c.h
 * Author:   declis (xdec.de)
 ************************************************/

#ifndef LIB_FUNC_C_H_
#define LIB_FUNC_C_H_

#define size 16         /* define size=16 */
#define value 0         /* define termination value */

char copy_data_ram(const char*,char*);

#endif /*LIB_FUNC_C_H_*/

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