83 lines
1.3 KiB
ArmAsm
83 lines
1.3 KiB
ArmAsm
.syntax unified
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.cpu cortex-m4
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.thumb
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.macro BKPT_WRITE addr_src
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mov r1, \addr_src
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mov r0, 0x4
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bkpt 0xAB
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.endm
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#define A 0x0321
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#define B 0x7005
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#define C 0x0050
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.section .text
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lab1_v2:
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push.n {lr}
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bl calculate_formula_v2
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bl int_to_str
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pop.n {pc}
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calculate_formula_v2:
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ldr r0, =A
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ldr r1, =B
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ldr r2, =C
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cmp r0, r1
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bgt gret
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blt less
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same: @ default
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add r2, r0, r2, lsr #3
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add r0, r2, r1
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b finish
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gret:
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rsb r0, r0, #192
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sub r0, r0, r1
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add r0, r2, r0, lsl #2
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b finish
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less:
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orr r1, r1, r2
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mul r0, r0, r1
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finish:
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mov r10, r0
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mov pc, lr
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int_to_str:
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mov r3, sp
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@ write newline + NULL terminator
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mov r5, #0x000A
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strh r5, [r3, #-2]!
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@ --- handmade modulo ---
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mov r4, #10
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iterate:
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mov r1, r0 @ save orig to r1
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udiv r0, r0, r4 @ orig/10 and overwrite old orig value
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mul r2, r0, r4 @ orig/10*10, place separately
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subs r5, r1, r2 @ orig - orig/10*10 => modulo (and update flags)
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beq check_if_pending_digits_exist
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proceed_with_conversion:
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add r5, #48 @ int -> char (only digits, so it's fine)
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strb r5, [r3, #-1]! @ write next char to RAM
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b iterate
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check_if_pending_digits_exist:
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cmp r0, #0
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bne proceed_with_conversion
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BKPT_WRITE r3
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mov pc, lr
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