diff options
Diffstat (limited to 'atk16_asm/builtin_asm/std_mem.atk16')
| -rw-r--r-- | atk16_asm/builtin_asm/std_mem.atk16 | 62 |
1 files changed, 62 insertions, 0 deletions
diff --git a/atk16_asm/builtin_asm/std_mem.atk16 b/atk16_asm/builtin_asm/std_mem.atk16 index 43d00ea..5855879 100644 --- a/atk16_asm/builtin_asm/std_mem.atk16 +++ b/atk16_asm/builtin_asm/std_mem.atk16 @@ -41,3 +41,65 @@ @label memcopy_done stack_restore RD RE RF return + +@label memcompare + ; compares two blocks of memory + ; parameters: RA = src1 (source address 1) + ; RB = src2 (source address 2) + ; RC = n (number of words to compare) + ; returns: RG = 1 if the blocks are equal, 0 otherwise + stack_stash RA RB RC RD RE + ldi 0 RG ; RD := 0 (result) + +@label memcompare_loop + subi RC 0 RC + bri zero memcompare_result_equal ; exit the loop + + ldr RA RD ; RD := left value + ldr RB RE ; RE := right value + + sub RD RE RD ; RD := left - right + bri zero memcompare_continue ; if left == right, continue the loop + + jpi memcompare_end ; if left != right, exit the loop + +@label memcompare_continue + inc RA ; RA := RA + 1 + inc RB ; RB := RB + 1 + dec RC ; RC := RC - 1 + jpi memcompare_loop ; repeat the loop + +@label memcompare_result_equal + ldi 1 RG ; RG := 1 (result) + +@label memcompare_end + stack_restore RA RB RC RD RE + return + + +@label string_compare + ; compares two strings + ; parameters: RA = str1 (source address 1) + ; RB = str2 (source address 2) + ; returns: RG = 1 if the strings are equal, 0 otherwise + + stack_stash RA RB RC RD RE + ldi 0 RG ; RD := 0 (result) + + ldr RA RD ; RD := left string length + ldr RB RE ; RE := right string length + + sub RD RE RD ; RD := left length - right length + bri zero string_compare_same_length ; if equal length, use memcompare + + jpi string_compare_end ; else if different length, exit + +@label string_compare_same_length + inc RA + inc RB + mov RE RC + calli memcompare ; return value implicitly returned in RG + +@label string_compare_end + stack_restore RA RB RC RD RE + return |