I have these input variables:
uint16 temperature = 0x1f12;
uint8 array[8] = {0,0,0,...0}
And I want to have
array8[0] = '1';
array8[1] = 'f';
array8[2] = '1';
array8[3] = '2';
array8[4] = '\0';
array8[5] = '\0';
array8[6] = '\0';
array8[7] = '\0';
However, for memory problems (I'm working with microcontrollers!) I need to avoid functions such as sprintf, printf, puts, etc.
How should I do?
Best regards,
Use recursion to determine 1 hex digit at a time.
// print digit at the end and return the next address
static char *itohexa_helper(char *dest, unsigned x) {
if (x >= 16) {
dest = itohexa_helper(dest, x/16);
}
*dest++ = "0123456789abcdef"[x & 15];
return dest;
}
char *itohexa(char *dest, unsigned x) {
*itohexa_helper(dest, x) = '\0';
return dest;
}
int main(void) {
char array[8];
uint16_t temperature = 0x1f11;
puts(itohexa(array, temperature));
puts(itohexa(array, 0));
puts(itohexa(array, 0x1234567));
puts(itohexa(array, UINT_MAX & 0xFFFFFFF));
}
Output
1f11
0
1234567
fffffff
uint16 temperature = 0x89ab; would have been clearer. Will reverse.
This code uses only 8 additional bytes in stack(int i, j).
int i;
for (i = 0; i < 8; i++) {
array[7 - i] = temperature % 16;
temperature /= 16;
if (temperature == 0)
break;
}
if (i == 8)
i--;
int j;
for (j = 0; j <= i; j++)
array[j] = array[7 - i + j];
for (j = i + 1; j < 8; j++)
array[j] = 0;
for (j = 0; j < 8; j++)
if (array[j] < 10)
array[j] += '0';
else
array[j] += 'a' - 10;
This code first converts temperature = 0x1f12 to array[8] = { 0, 0, 0, 0, 1, 15, 1, 2}.
Then shifts the elements of array so that it becomes array[8] = { 1, 15, 1, 2, 0, 0, 0, 0 }.
And then converts the numbers to corresponding characters: array[8] = { '1', 'f', '1', '2', '0', '0', '0', '0' }.
Note also that this if condition
if (i == 8)
i--;
is never met, since break condition always suffices in the first for loop, even for temperature >= 0x10000000. It's just there in the hope that it might help someone understand this code.
temperature = 0x123, this answers forms array "12300000", certainly not OP's goal.
int convert()
{
uint16_t temperature = 0x1f11;
uint8_t array[8] = {0,0,0,0,0,0,0,0};
int i = 0;
for(i = 0; i < 8; i++){
array[i] = (0xf000 & temperature) >> 12 ;
temperature <<= 4;
printf("array[%d] = %x\n", i ,array[i]);
}
return(0);
}
'0'if between 0 and 9, else add'A'-10.'a' - 10which is'W'array[]write leading0digits? Example: shouldtemperature = 0x123-->"123"or"0123"or it makes no difference?array8 = '1f12'does not make any sense. Please rollback your question.