AVR-Chat

AHA!  That sourfce does it.  I see that the interrupts are ALREADY 
cleared in the source you gave me.  I also get the disasm version of 
my code and I see that the libc looks to be identical.

In the Disasm, I can see that the interrupts are cleared.  I could 
not see where they were set again, but in the original source you 
include, I see that a register is used to store SREG, and then to 
restore it.

So, it seeme to me that the interrupts ARE suspended in the libc 
versions.  I was under the impression that they did not suspend 
interrupts, but I can see the cli.

So, I do not need to hand-tune the library eeprom handlers to 
suspend interrupts.  I forget what made me think that the library 
routines did not clear interrupts....

THANKS!  You helped me a lot, and also saved me some time trying to 
write my own stuff.

-Tony

--- In AVR-Chat@yahoogroups.com, David Kelly <dkelly@h...> wrote:
> 
> On Apr 26, 2005, at 11:04 AM, arhodes19044 wrote:
> 
> > I can not find the source files for the eeprom routines in 
libc.  I
> > want to disable interrupts for the minimum necessary period while
> > writing to EEPROM.  I bet that the clear/set should occur in the
> > write_byte function, since that is probably called by all the 
larger
> > size write functions.
> 
> The sources are:
> 
> /* write a byte to EEPROM */
> /* void eeprom_write_byte(uint8_t *addr, uint8_t val); */
> /* addr = r25:r24, val = r22 */
> #define val rP3
> 
>          .global _U(eeprom_write_byte)
> 
> _U(eeprom_write_byte):
>          sbic    _SFR_IO_ADDR(EECR), EEWE
>          rjmp    _U(eeprom_write_byte)   /* make sure EEPROM is 
ready */
> #ifdef EEARH
>          out     _SFR_IO_ADDR(EEARH), addr_hi
> #endif
>          out     _SFR_IO_ADDR(EEARL), addr_lo
>          out     _SFR_IO_ADDR(EEDR), val
>          in      __tmp_reg__, _SFR_IO_ADDR(SREG)
>          cli                     ; /* no ints between setting 
EEMWE and 
> EEWE */
>          sbi     _SFR_IO_ADDR(EECR), EEMWE
>          sbi     _SFR_IO_ADDR(EECR), EEWE
>          out     _SFR_IO_ADDR(SREG), __tmp_reg__
>          ret
> #undef val
> 
> /* write a block of bytes to EEPROM */
> /* void eeprom_write_block (const void *buf, void *addr, size_t 
n); */
> /* buf = r25:r24, addr = r23:r22, n = r21:r20 */
> 
>          .global _U(eeprom_write_block)
> 
> _U(eeprom_write_block):
>          cp      n_lo, __zero_reg__              ; check if really 
there 
> is something to write
>          cpc     n_hi, __zero_reg__
>          breq    eeprom_write_block_done
>          LOAD_X(buf_lo, buf_hi)
>          in      buf_lo, _SFR_IO_ADDR(SREG)      ; reuse buf_lo as 
the 
> SREG temporary storage
> eeprom_write_block_busy:
>          sbic    _SFR_IO_ADDR(EECR), EEWE
>          rjmp    eeprom_write_block_busy         ; make sure 
EEPROM is 
> ready
> #ifdef EEARH
>          out     _SFR_IO_ADDR(EEARH), addr_hi
> #endif
>          out     _SFR_IO_ADDR(EEARL), addr_lo
>          ld      __tmp_reg__, X+
>          out     _SFR_IO_ADDR(EEDR), __tmp_reg__
>          cli                                     ; no ints between 
> setting EEMWE and EEWE
>          sbi     _SFR_IO_ADDR(EECR), EEMWE
>          sbi     _SFR_IO_ADDR(EECR), EEWE
>          out     _SFR_IO_ADDR(SREG), buf_lo
>          subi    addr_lo, lo8(-1)
>          sbci    addr_hi, hi8(-1)
>          subi    n_lo, lo8(1)
>          sbci    n_hi, hi8(1)
>          brne    eeprom_write_block_busy
> eeprom_write_block_done:
>          ret
> 
> > How do I disasm only the required parts.
> 
> If you still have the Makefile I sent a while back, posted to the 
list, 
> it creates "object.elf" which is loaded into AVRStudio for 
debugging, 
> but also generates a text file named "object.list". I add 
object.list 
> to my PN2 project for quick access. Then text search (control-F) 
for 
> the string of interest.
> 
> > How do I even SEE the disasm'ed code while running avrsrudio?
> 
> Right mouse click on the source window, "view disassembly" or 
something 
> obvious to that effect. I have problems with AVRStudio getting out 
of 
> sync with the C source lines, stopping in mid-statement, and 
> automagically opening a disassembly window.
> 
> One advantage of using object.list described above is that the 
line of 
> C source code is inserted as comments immediately prior to the 
> generated code. AVRStudio does not insert the C source, but does 
> provide verbose descriptions of each assembly instruction.
> 
> Believe the command line to generate object.list is:
> 
> avr-objdump -DS object.elf > object.list
> 
> --
> David Kelly N4HHE, dkelly@H...
> 
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===
> Whom computers would destroy, they must first drive mad.