No need for branches, see comment above demonstrating sltu. For a long carry chain, I guess it might look like this: ; Inputs: x = 4-word number, in a3:a2:a

No need for branches, see comment above demonstrating sltu. For a long carry chain, I guess it might look like this: ; Inputs: x = 4-word number, in a3:a2:a1:a0, ; y = 1-word number, in a4. ; Output: x+y, 5-word number, in a4:a3:a2:a1:a0. add a0, a0, a4 sltu a4, a0, a4 ; a4 = carry bit add a1, a1, a4 sltu a4, a1, a4 ; a4 = carry bit again add a2, a2, a4 sltu a4, a2, a4 add a3, a3, a4 sltu a4, a3, a4