Clear the carry/borrow flag before add/sub

diff --git a/src/add_digits_asm.s b/src/add_digits_asm.s
index 39f4af9..8144acc 100644 (file)
--- a/src/add_digits_asm.s
+++ b/src/add_digits_asm.s
@@ -9,6 +9,7 @@
 # Result in %rax is the final result in the carry flag
 # Exploits the fact that inc and dec do not affect the carry flag
 add_digits:
+       addq $0, %rax
        loop:
                movq (%rsi), %rax # Temporarily store digit from second array
                adcq %rax, (%rdi) # Add digits in second and first array, store in first

diff --git a/src/sub_digits_asm.s b/src/sub_digits_asm.s
index 1a6ee3b..17d81c1 100644 (file)
--- a/src/sub_digits_asm.s
+++ b/src/sub_digits_asm.s
@@ -9,6 +9,7 @@
 # Result in %rax is the final result in the carry flag
 # Exploits the fact that inc and dec do not affect the carry flag
 sub_digits:
+       subq $0, %rax           # Reset the carry/borrow flag
        loop:
                movq (%rsi), %rax # Temporarily store digit from second array
                sbbq %rax, (%rdi) # Subtract digits in second and first array, store in first