Exercise 1: Write an ARM assembly language routine to count the number of 1s in a 32-bit word in ro and return the result in ri. code: OnesCount LDR ro, = 0x11AB003F MOV ri, #0x0 MOV r2, #32 MOVS ro, r0, ROR #1 ADDCS r1, r1, #1 SUBS r2, r2, #1 BNE OnesCount ; dummy value for rl (11 ones) ;clear ones counter ;use r2 as the loop counter Repeat: rotate ro right set flags ;if carry set increment ls counter idecrement loop counter ; until all bits tested If this was a subroutine Count, the code might be: ;set up dummy r2 area test, CODE, readwrite ADR sp, Stacki LDR r2,=0xFFFFFFFF STR r2, [sp] LDR ro, = OxFFAB123A BL Count MOV r3, rl NOP NOP ; dummy data ; call routine ; read result ;save r2 and return on the stack Count STMFD sp!, {r2, lr} MOV r1, #0x0 MOV r2, #4 OnesCount MOVS ro, r0, ROR #1 ADDCS ri, r1, #1 SUBS r2, r2, #1 BNE OnesCount LDMFD sp!, {r2, pc} ; restore r2 and return Stack Stacki DCD 0,0,0,0,0 DCD 0,0,0,0,0 Exercise 1: Write an ARM assembly language routine to count the number of 1s in a 32-bit word in ro and return the result in ri. code: OnesCount LDR ro, = 0x11AB003F MOV ri, #0x0 MOV r2, #32 MOVS ro, r0, ROR #1 ADDCS r1, r1, #1 SUBS r2, r2, #1 BNE OnesCount ; dummy value for rl (11 ones) ;clear ones counter ;use r2 as the loop counter Repeat: rotate ro right set flags ;if carry set increment ls counter idecrement loop counter ; until all bits tested If this was a subroutine Count, the code might be: ;set up dummy r2 area test, CODE, readwrite ADR sp, Stacki LDR r2,=0xFFFFFFFF STR r2, [sp] LDR ro, = OxFFAB123A BL Count MOV r3, rl NOP NOP ; dummy data ; call routine ; read result ;save r2 and return on the stack Count STMFD sp!, {r2, lr} MOV r1, #0x0 MOV r2, #4 OnesCount MOVS ro, r0, ROR #1 ADDCS ri, r1, #1 SUBS r2, r2, #1 BNE OnesCount LDMFD sp!, {r2, pc} ; restore r2 and return Stack Stacki DCD 0,0,0,0,0 DCD 0,0,0,0,0