Write equivalent c++ code

ARM CODE LDR R1, Fa LDR R1, [R1] LDR R2,-b LDR R2, [R2] MOV R3, R2, LSL#1 MUL R2, R3, R2 CMP R1, #0 MVNLT R2, R2 ADDLT R2, R2, #1 LDR R3,-c STR R1, [R3] SWI 0x11