// bubble-sort.S file template, rename and implement the algorithm
// Test algorithm in qtrvsim_gui program
// Select the CPU core configuration with delay-slot
// This setups requires (for simplicity) one NOP instruction after
// each branch and jump instruction (more during lecture about pipelining)
// The code will be compiled and tested by external riscv64-unknown-elf-gcc
// compiler by teachers, you can try make in addition, but testing
// by internal assembler should be enough
// copy directory with the project to your repository to
// the directory work/bubble-sort
// critical is location of the file work/bubble-sort/bubble-sort.S
// which is checked by the scripts
// Directives to make interesting windows visible
#pragma qtrvsim show registers
#pragma qtrvsim show memory
.option norelax
.globl array_size
.globl array_start
.text
.globl _start
_start:
la a0, array_start
la a1, array_size
lw a1, 0(a1) // number of elements in the array, N = 15
addi x1, x0, 0 // x1 is i = 0
addi x6, x0, 1 // x6 is 1
outer_loop:
beq x1, a1, end_loop// if i == N, jump to end_loop
la a0, array_start // reset adress
addi x2, x0, 0 // x2 is j = 0
addi x1, x1, 1 // i++
sub a2, a1, x6 // N - 1 for inner loop
sub a2, a2, x1 // N - 1 - i
j inner_loop
inner_loop:
beq x2, a2, outer_loop // if j == N - 1 - i, jump to outer_loop
lw x3, 0x0(a0)
lw x4, 0x4(a0)
addi x2, x2, 1 // j++
slt x5, x4, x3 // x5 = x4 < x3 ? 1 : 0
beq x5, x0, after_inner // if x5 = 0, jump to after_inner
// swap
sw x4, 0x0(a0)
sw x3, 0x4(a0)
after_inner:
addi a0, a0, 4 // increment address by 4 bytes (1 word)
j inner_loop
//Final infinite loop
end_loop:
fence // flush cache memory
ebreak // stop the simulator
j end_loop
.data
// .align 2 // not supported by qtrvsim yet
array_size:
.word 15
array_start:
.word 5, 3, 4, 1, 15, 8, 9, 2, 10, 6, 11, 1, 6, 9, 12
// Specify location to show in memory window
#pragma qtrvsim focus memory array_size
Write, Run & Share Assembly code online using OneCompiler's Assembly online compiler for free. It's one of the robust, feature-rich online compilers for Assembly language. Getting started with the OneCompiler's Assembly compiler is simple and pretty fast. The editor shows sample boilerplate code when you choose language as Assembly and start coding.
Assembly language(asm) is a low-level programming language, where the language instructions will be more similar to machine code instructions.
Every assembler may have it's own assembly language designed for a specific computers or an operating system.
Assembly language requires less execution time and memory. It is more helful for direct hardware manipulation, real-time critical applications. It is used in device drivers, low-level embedded systems etc.
Assembly language usually consists of three sections,
Data section
To initialize variables and constants, buffer size these values doesn't change at runtime.
bss section
To declare variables
text section
_start specifies the starting of this section where the actually code is written.
There are various define directives to allocate space for variables for both initialized and uninitialized data.
variable-name define-directive initial-value
| Define Directive | Description | Allocated Space |
|---|---|---|
| DB | Define Byte | 1 byte |
| DW | Define Word | 2 bytes |
| DD | Define Doubleword | 4 bytes |
| DQ | Define Quadword | 8 bytes |
| DT | Define Ten Bytes | 10 bytes |
| Define Directive | Description |
|---|---|
| RESB | Reserve a Byte |
| RESW | Reserve a Word |
| RESD | Reserve a Doubleword |
| RESQ | Reserve a Quadword |
| REST | Reserve a Ten Bytes |
Constants can be defined using
CONSTANT_NAME EQU regular-exp or value
%assign constant_name value
%define constant_name value
Loops are used to iterate a set of statements for a specific number of times.
mov ECX,n
L1:
;<loop body>
loop L1
where n specifies the no of times loops should iterate.
Procedure is a sub-routine which contains set of statements. Usually procedures are written when multiple calls are required to same set of statements which increases re-usuability and modularity.
procedure_name:
;procedure body
ret