Semester assignments for the course "Microprocessors and Peripherals" of THMMY in AUTH university.
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#include <stdio.h>
#include <stdint.h>
static const uint8_t hashtbl[] = {
18, 11, 10, 21, 7, 5, 9, 22, 17, 2, 12, 3, 19, 1, 14, 16, 20, 8, 23, 4, 26, 15, 6, 24, 13, 25
};
__asm int generate_hash( const char *str, const uint8_t *hashtbl )
{
// Define names for used registers
input_str RN r0
hashtbl RN r1
curr_char RN r2
hash_val RN r3
MOV hash_val, #0 // Initialize hash_val to zero
hash_loop
LDRB curr_char, [input_str] // Load byte into curr_char from memory pointed to by input_str
CMP curr_char, #'0' // Compare it with 0
BLS hash_skip // If it is lower or same in the ASCII table, then skip this character
CMP curr_char, #'9' // Compare it with 9
SUBLS hash_val, curr_char // If byte is lower or same, then subtract its value from the hash_val
ADDLS hash_val, #48 // Add 48 to the hash_val because ASCII '0' index is 48 decimal
BLS hash_skip // Then move the the next character
CMP curr_char, #'A' - 1 // Compare it with the character before 'A'
BLS hash_skip // If it is lower or same in the ASCII table, then skip this character
CMP curr_char, #'Z' // Compare it with the 'Z' character
BHI hash_skip // If it is higher in the ASCII table, then skip this character
SUB r4, curr_char, #65 // Subtract 65 from curr_char because the ASCII 'A' index is 65 decimal and store in r4
ADD r4, hashtbl, r4 // Add the address of the start of the lookup table to r4
LDRB r5, [r4] // Load byte into r5 from memory pointed to by r4 (character hash value)
ADD hash_val, r5 // Add the character hash value to the hash_val
hash_skip
ADDS input_str, input_str, #1 // Increment the input_str pointer
CMP curr_char, #0 // Check if the byte is 0
BNE hash_loop // If not, repeat loop
MOVEQ r0, hash_val // Else store hash_val to r0
BX lr // Return from subroutine
}
int main(void)
{
static char STRING_TO_HASH[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789!!@#$%*&";
int hash = 0;
hash = generate_hash(STRING_TO_HASH, hashtbl);
printf("%d", hash);
return 0;
}