Hi, I am tasked with writing selection sort in assembly. We are writing for the ARM processor.
Currently, this is what I have:
sort2:
73 stmdb sp!, {v1-v5, lr} @ Copy registers to stack
74 ldrb r5, [a2] @ J = n
75
76 ldrb v2, [a1]
77 cmp a2, #1
78 beq skip_sorting
79
80 sub r5, r5, #1 @ j = N-1
81 outer_loop:
82 cmp r5, #0 @ j > 0 add j-- at the bottom
83 beq skip_sorting
84
85 inner_loop:
86 mov r6, r5 @ k = j
87 sub r6, r6, #1 @ k = j-1
88 cmp r6, #-1 @k >= 0
89 b outer_loop
90 cmp
91
92
93
94 skip_sorting:
95 ldmia sp!, {v1-v5, pc} @ Copy stack back into registers
where I am following the prototype of:
59 for (j=N-1; j>0; j=j-1 {
60 for (k=j-1; k >= 0; k=k-1 {
61 if (list[k] > list[j]) {
62 tmp = list[k];
63 list[k]= list[j];
64 list[j] = tmp;
65 }
66 }
67 }
a1 is a pointer to the byte array of Length N
a2 the value of N
I felt pretty slick up until line 61 of the prototype c code, but then I realized I know absolutely nothing about asm and should ask for help.
if a1 is a pointer to the byte array, how do I access array[n], array[n+1]? Is my offset dependent on the platform we are running, or is this layer hidden from the programmer?
Any help is much appreciated.
