Computer Engineering

AREA my_fancy_asm_code, CODE, READONLY ; Define the program area ; Export functions defined in this file. These functions need to be declared ; in the file calling them. EXPORT task5 EXPORT task6 EXPORT task7 EXPORT task10 EXPORT task11 EXPORT task12 EXPORT task13 EXPORT task14 EXPORT task15 IMPORT gPtrArray1 IMPORT gPtrArray2 IMPORT gVar1 IMPORT gVar2 ALIGN ; Align the data in the boundary of 4 bytes. task5 PROC LDR r0, =0x10 ; Pseudo code; see the disassembly for the true code LDR r1, =0x12345678 ; Pseudo code; see the disassembly for the true code LDR r2, =gVar1 ; Loading the address of the global variable gVar1 LDR r3, =gPtrArray1 ; Loading the address of the global variable gPtrArray1 BX lr ENDP task6 PROC LDR r0, =0x10 ; Pseudo code; see the disassembly for the true code LDR r1, =gVar1 ; Loading the address of the global variable gVar1 LDR r2, [r1] ADD r0, r2 STR r0, [r1] BX lr ENDP task7 PROC LDR r0, =0x12345678 ; Pseudo code; see the disassembly for the true code LDR r1, =gVar1 LDR r1, [r1] ADD r0, r1 LDR r2, =gVar2 ; Loading the address of the global variable gVar2 STR r0, [r2] BX lr ENDP task10 PROC LDR r0, =gPtrArray1 ; Loading the address of the global variable gPtrArray1 LDR r0, [r0] ; Loading the content of the global variable gPtrArray1 LDR r1, =gVar1 ; Loading the address of the global variable gVar1 LDR r1, [r1] ; Loading the content of the global variable gVar1 MOV r2, #0 ; variable (int) i task10_loop CMP r2, r1 ; test = r2 - r1 BGE task10_end ; if test >= 0, then branch to task10_end MOV r3, r2, LSL #1 ; r3 <- 2 * r2 ADD r3, #1 ; r3 <- r3 + 1 STR r3, [r0, r2, LSL #2] ; r3 -> mem[r0 + 4*r2] or r3 -> mem[r0 + i] ADD r2, #1 ; r2 <- r2 + 1 B task10_loop ; branch to task10_loop task10_end BX lr ; return ENDP ; If you need to use registers starting from r4, you need to PUSH them first to save the ; run-time environment for the caller. You need to POP them up at the exit of the code. task11 PROC LDR r0, =gPtrArray2 LDR r0, [r0] LDR r1, =gVar1 LDR r1, [r1] MOV r2, #0 task11_loop CMP r2, r1 BGE task11_end MOV r3, r2, LSL #2 ADD r3, #1 STR r3, [r0, r2, LSL #2] ADD r2, #1 B task11_loop task11_end BX lr ENDP task12 PROC PUSH {r4, lr} LDR r0, =gPtrArray1 LDR r0, [r0] LDR r4, =gPtrArray2 LDR r4, [r4] LDR r1, =gVar1 LDR r1, [r1] MOV r2, #0 task12_loop CMP r2, r1 BGE task12_end LDR r3, [r0, r2, LSL #2] STR r3, [r4, r2, LSL #2] ADD r3, #1 STR r3, [r0, r2, LSL #2] ADD r2, #1 B task12_loop task12_end POP {r4, pc} ; Pop lr to pc, which is the same as BX lr. ENDP task13 PROC PUSH {r4-r5, lr} LDR r0, =gPtrArray1 LDR r0, [r0] LDR r4, =gPtrArray2 LDR r4, [r4] LDR r1, =gVar1 LDR r1, [r1] SUB r1, #1 MOV r2, #0 task13_loop CMP r2, r1 BGE task13_end LDR r3, [r0] LDR r5, [r0, #4] ADD r3, r5 STR r3, [r4, r2, LSL #2] ADD r2, #1 ADD r0, #4 B task13_loop task13_end POP {r4-r5, pc} ENDP task14 PROC PUSH {r4-r5, lr} LDR r0, =gPtrArray1 LDR r0, [r0] LDR r4, =gPtrArray2 LDR r4, [r4] LDR r1, =gVar1 LDR r1, [r1] SUB r1, #1 MOV r2, #0 task14_loop CMP r2, r1 BGE task14_end LDR r3, [r0] LDR r5, [r0, #4]! ADD r3, r5, LSL #1 STR r3, [r4, r2, LSL #2] ADD r2, #1 B task14_loop task14_end POP {r4-r5, pc} ENDP task15 PROC PUSH {r4-r5, lr} LDR r0, =gPtrArray1 LDR r0, [r0] LDR r4, =gPtrArray2 LDR r4, [r4] LDR r1, =gVar1 LDR r1, [r1] SUB r1, #1 MOV r2, #0 task15_loop CMP r2, r1 BGE task15_end LDR r3, [r0], #4 LDR r5, [r0] ADD r3, r5, LSL #2 STR r3, [r4, r2, LSL #2] ADD r2, #1 B task15_loop task15_end POP {r4-r5, pc} ENDP END ; End of the entire file