Am 29.07.2015 um 14:34 schrieb Karel Gardas:
Once it boots, tell me how to find the asnwers to your
questions.
compile with gcc test.cpp and run
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#include <stdint.h>
#include <stdio.h>
#include <stddef.h>
#include <string.h>
#include <assert.h>
int main()
{
uint16_t value = 0x1234;
{
volatile uint8_t* ptr = (uint8_t*)&value;
printf("endianess: %s\n", ptr[0]==0x34 ? "little":"big");
}
uint8_t buffer[1+sizeof(value)]={0};
uint8_t* ptr = buffer;
if(ptrdiff_t(ptr) % 2 == 0)
{
++ptr;
}
uint16_t* unaligned_word = (uint16_t*)ptr;
::memcpy(unaligned_word, &value, sizeof(value));
printf("try to access unaligned word\n");
uint16_t read = *unaligned_word; // here can happen Bus-Errors,
Exceptions, whatever your architecture likes
printf(" equal to 0x%04X: %s\n", value, read == value ?
"YES":"!!NO!!"); // sometimes you get the value - but its still wrong
printf(" value: 0x%04X\n", read);
printf("done\n");
return 0;
}
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