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AW: [avr-gcc-list] Macro to read /write long to eeprom


From: Haase Bjoern (PT-BEU/EMT) *
Subject: AW: [avr-gcc-list] Macro to read /write long to eeprom
Date: Wed, 10 Aug 2005 08:54:20 +0200

Hi,

If you are using avr-libc-1.2.5 you could write a fairly efficient function by 
using the following code.

You will be having 4 calls, but never the less this will be more efficient than 
the wrapper function using read_block that forces all the values once to memory.

Yours,

Björn


/* Code functional only with avr-libc-1.2.5 */

uint16_t static inline __attribute__ ((always_inline)) 
eeprom_read_long_word (const uint32_t *addr);

uint16_t
eeprom_read_long_word (const uint32_t *addr)
{
  uint32_t result;
  asm ( XCALL " __eeprom_read_byte_" _REG_LOCATION_SUFFIX CR_TAB
        "mov %A1,__tmp_reg__"    CR_TAB
        XCALL " __eeprom_read_byte_" _REG_LOCATION_SUFFIX CR_TAB
        "mov %B1,__tmp_reg__"    CR_TAB
        XCALL " __eeprom_read_byte_" _REG_LOCATION_SUFFIX CR_TAB
        "mov %C1,__tmp_reg__"    CR_TAB
        XCALL " __eeprom_read_byte_" _REG_LOCATION_SUFFIX CR_TAB
        "mov %D1,__tmp_reg__"
       : "+x" (addr),
         "=r" (result)
       : );
  return result;
}

void static inline __attribute__ ((always_inline))
eeprom_write_long_word (uint16_t *addr,uint32_t value); 

void 
eeprom_write_long_word (uint16_t *addr,uint32_t value)
{
  asm volatile (
         "mov __tmp_reg__,%A1"     CR_TAB
         XCALL " __eeprom_write_byte_" _REG_LOCATION_SUFFIX CR_TAB
         "mov __tmp_reg__,%B1"     CR_TAB
         XCALL " __eeprom_write_byte_" _REG_LOCATION_SUFFIX CR_TAB
         "mov __tmp_reg__,%C1"     CR_TAB
         XCALL " __eeprom_write_byte_" _REG_LOCATION_SUFFIX CR_TAB
         "mov __tmp_reg__,%D1"     CR_TAB
         XCALL " __eeprom_write_byte_" _REG_LOCATION_SUFFIX
       : "+x" (addr)
       : "r"  (value)
       : "memory"
      );
}


 

-----Urspr√ľngliche Nachricht-----
Von: address@hidden [mailto:address@hidden Im Auftrag von Royce Pereira
Gesendet: Dienstag, 9. August 2005 20:54
An: AVR-GCC
Betreff: [avr-gcc-list] Macro to read /write long to eeprom

Hi,
Is there a macro to read or write a long word (32 bits) to eeprom?
For the last hour I've been trying to write one unsuccessfully.

Thanks,
--Royce.

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