I am looking to implement the prototype for read_and_write, but couldn't get it right. Any help is appreciated. I am able to extract bits.
In this below code for write_val1, my intent is to write only the first 9 bits of final_val into read_data. The rest 7 bits of read_data should remain untouched. Expected output for write_val1 = 0x0080
Similarly for write_val2, my intent is to write only next 8 bits from final_val into read_data. The rest 8 bits of read_data should remain untouched. Expected output for write_val2 = 0x2700
Similarly for write_val3, my intent is to write only next 3 bits(010) from final_val into a position[11:13] of read_data leaving rest of read_data untouched.
Expected output = 0x5448 ; For example: pick 010 extracted bit from write_val3; 0x3048 = 0111 0000 0100 1000; 0x5048 = 0101 0000 0100 1000
#include <stdio.h>
#include <stdint.h>
int bitExtracted(uint16_t read_data, uint8_t n_bits, uint8_t pos)
{
return (((1 << n_bits) - 1) & (read_data >> (pos - 1)));
}
void read_and_write(uint32_t* final_val, uint16_t* write_val, uint8_t start_pos, uint8_t end_pos)
{
uint32_t temp = *final_val;
*write_val = (uint16_t) ((temp >> start_pos) & ((1 << end_pos) - 1)); *final_val = (temp >> end_pos); printf("\n temp %x, write_val %x, final_val %x ", temp, *write_val, *final_val);
}
void main()
{
uint16_t read_data = 0x0; uint16_t ext_val1 = bitExtracted(read_data, 9, 1); uint8_t ext_val2 = bitExtracted(read_data, 8, 1); uint8_t ext_val3 = bitExtracted(read_data, 3, 5); uint32_t final_val = 0x0; uint16_t write_val1, write_val2, write_val3;
uint8_t start_pos = 0, end_pos =8;
ext_val1 = 0x80, ext_val2 = 0x0, ext_val3 = 0x2;
final_val = (ext_val1 | (ext_val2 << 9) | (ext_val3 << 17));
printf ("\n final_val %x", final_val);
read_and_write(&final_val, &write_val1, 0, 9);
read_data = 0x80;
write_val1 = write_val1 | read_data;
start_pos = 0;
end_pos = 7;
read_data = 0x27b7;
read_and_write(&final_val, &write_val2, start_pos, end_pos);
write_val2 = write_val2 | read_data;
start_pos = 11;
end_pos = 13;
read_data = 0x3048;
read_and_write(&final_val, &write_val3, start_pos, end_pos);
write_val3 = write_val3 | read_data;
printf ("\n val1 0x%x val2 0x%x val3 0x%x final_val 0x%x", write_val1, write_val2, ext_val3, final_val);
}
What I have tried:
I am able to extract bits, and combine into one final_val. I am unable to modify registers in that specific start_pos and end_pos.