On Thu, Feb 5, 2009 at 2:30 PM, Bob Paddock <graceindustr...@gmail.com> wrote:
> I have code that calculates the CRC of Flash at power up, that works
> fine on the AT90CAN64 part.
> When I move the CRC function to the Tiny88 it does not work.
....
> What is going on here?
>
> This is with avr-gcc (WinAVR 20081205) 4.3.2.
/* Here is a test case: */
#include <stdint.h>
#include <avr/io.h>
uint16_t __data_load_end[1]; /* Defined by the linker script. Set to
address of last byte of .text+.data section */
int main( void )
{
uint16_t flash_end_u16 = (uint16_t) &(__data_load_end[0]);
/* Pointless code to get something in flash: */
DDRB = (uint8_t) -1;
PORTB = (uint8_t) (flash_end_u16>>8);
PORTB = (uint8_t) flash_end_u16;
}
00000076 <main>:
#include <avr/io.h>
uint16_t __data_load_end[1]; /* Defined by the linker script. Set to
address of last byte of .text+.data section */
int main( void )
{
uint16_t flash_end_u16 = (uint16_t) &(__data_load_end[0]);
76: 20 e0 ldi r18, 0x00 ; 0
78: 31 e0 ldi r19, 0x01 ; 1
[The above is wrong.]
/* Pointless code to get something in flash: */
DDRB = (uint8_t) -1;
7a: 8f ef ldi r24, 0xFF ; 255
7c: 84 b9 out 0x04, r24 ; 4
PORTB = (uint8_t) (flash_end_u16>>8);
7e: 35 b9 out 0x05, r19 ; 5
PORTB = (uint8_t) flash_end_u16;
80: 25 b9 out 0x05, r18 ; 5
}
82: 80 e0 ldi r24, 0x00 ; 0
84: 90 e0 ldi r25, 0x00 ; 0
86: 08 95 ret
00000088 <_exit>:
88: f8 94 cli
0000008a <__stop_program>:
8a: ff cf rjmp .-2 ; 0x8a <__stop_program>
map:
*(COMMON)
0x00800102 PROVIDE (__bss_end, .)
0x0000008c __data_load_start = LOADADDR (.data)
0x0000008c __data_load_end =
(__data_load_start + SIZEOF (.data))
sym:
00000088 W exit
0000008a t __stop_program
0000008c A __data_load_end
0000008c A __data_load_start
0000008c T _etext
000001ff W __stack
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