Bogo Sort in X86_64 (#517)

* adding bogo_sort.s

* updating bogo_sort.md

Author: Gathros

contents/bogo_sort/bogo_sort.md

@@ -55,6 +55,8 @@ In code, it looks something like this:
 [import:3-8, lang:"lisp"](code/racket/bogo_sort.rkt)
 {% sample lang="st" %}
 [import:2-6, lang:"st"](code/smalltalk/bogosort.st)
+{% sample lang="asm-x64" %}
+[import:93-113, lang:"asm-x64"](code/asm-x64/bogosort.s)
 {% sample lang="lisp" %}
 [import:20-24, lang:"lisp"](code/lisp/bogo-sort.lisp)
 {% endmethod %}
@@ -111,6 +113,8 @@ We are done here!
 [import, lang:"lisp"](code/racket/bogo_sort.rkt)
 {% sample lang="st" %}
 [import, lang:"st"](code/smalltalk/bogosort.st)
+{% sample lang="asm-x64" %}
+[import, lang:"asm-x64"](code/asm-x64/bogosort.s)
 {% sample lang="lisp" %}
 [import, lang:"lisp"](code/lisp/bogo-sort.lisp)
 {% endmethod %}

contents/bogo_sort/code/asm-x64/bogo_sort.s

@@ -0,0 +1,147 @@
+.intel_syntax noprefix
+
+.section .rodata
+  array:
+    .align 16
+    .int 1, 3654, 78, 654, -234, -12, 4, 3, -6, -100
+    .equ array_len, (.-array) / 4
+  array_fmt: .string "%d "
+  lf:        .string "\n"
+  unsorted:  .string "Unsorted array: "
+  sorted:    .string "Sorted array: "
+
+.section .text
+  .global main
+  .extern printf, rand, srand
+
+# rdi - array ptr
+# rsi - array size
+print_array:
+  push   r12
+  push   r13
+  mov    r12, rdi                 # Loop variable
+  lea    r13, [rdi + 4 * rsi]     # Pointer after the last element
+print_array_loop:
+  cmp    r12, r13                 # If we're done iterating over the array then bail
+  jge    print_array_done
+  mov    rdi, OFFSET array_fmt    # Otherwise print the current value
+  mov    esi, DWORD PTR [r12]
+  xor    rax, rax
+  call   printf
+  lea    r12, [r12 + 4]           # And increment the loop variable pointer
+  jmp    print_array_loop
+print_array_done:
+  mov    rdi, OFFSET lf           # Print a closing newline
+  xor    rax, rax
+  call   printf
+  pop    r13
+  pop    r12
+  ret
+
+# rdi - array ptr
+# rsi - array size
+# RET rax - boolean
+is_sorted:
+  sub    rsi, 1                   # Getting array + n and *array + n - 1
+  lea    rcx, [rsi - 1]
+  lea    rcx, [rdi + 4 * rcx]
+  lea    rsi, [rdi + 4 * rsi]
+is_sorted_loop:
+  cmp    rsi, rdi                 # Check if array + n - 1 == array
+  je     is_sorted_done
+  mov    edx, DWORD PTR [rsi]     # Load value to register
+  xor    rax, rax                 # Set rax to 0
+  cmp    edx, DWORD PTR [rcx]     # Check if array[n] < array[n - 1]
+  jl     is_sorted_return
+  sub    rcx, 4                   # If not make pointers go to down an element
+  sub    rsi, 4
+  jmp    is_sorted_loop
+is_sorted_done:
+  mov    rax, 1                   # If sorted then set rax to 1
+is_sorted_return:
+  ret                             # Return
+
+# rdi - array ptr
+# rsi - array size
+shuffle:
+  push   r12
+  push   r13
+  push   r14
+  push   r15
+  mov    r12, rdi                          # Save parameters
+  mov    r13, rsi
+  xor    r14, r14
+shuffle_loop:
+  cmp    r14, r13                          # Check if i == array size
+  je     shuffle_done
+  mov    r15d, DWORD PTR [r12 + r14 * 4]   # Save array[i]
+  call   rand                              # Swap a random element with array[i]
+  xor    edx, edx
+  div    r13                               # Mod random number to keep in array
+  mov    eax, DWORD PTR [r12 + rdx * 4]
+  mov    DWORD PTR [r12 + r14 * 4], eax
+  mov    DWORD PTR [r12 + rdx * 4], r15d
+  add    r14, 1                            # increment then repeat
+  jmp    shuffle_loop
+shuffle_done:
+  pop    r15
+  pop    r14
+  pop    r13
+  pop    r12
+  ret
+
+# rdi - array ptr
+# rsi - array size
+bogo_sort:
+  push   r12
+  push   r13
+  mov    r12, rdi
+  mov    r13, rsi
+bogo_sort_loop:
+  mov    rdi, r12                         # Check if the array is sorted
+  mov    rsi, r13
+  call   is_sorted
+  test   rax, rax
+  jnz    bogo_sort_done
+  mov    rdi, r12                         # If not then shuffle
+  mov    rsi, r13
+  call   shuffle
+  jmp    bogo_sort_loop
+bogo_sort_done:
+  pop    r13
+  pop    r12
+  ret
+
+main:
+  # Set up our stack
+  sub    rsp, 40
+  # We load the array in chunks onto the stack
+  movaps xmm0, XMMWORD PTR [array]
+  movaps XMMWORD PTR [rsp], xmm0
+  movaps xmm0, XMMWORD PTR [array + 16]
+  movaps XMMWORD PTR [rsp + 16], xmm0
+  mov    rax, QWORD PTR [array + 32]
+  mov    QWORD PTR [rsp + 32], rax
+  # Print the unsorted array
+  mov    rdi, OFFSET unsorted
+  xor    rax, rax
+  call   printf
+  mov    rdi, rsp
+  mov    rsi, array_len
+  call   print_array
+  # Sort
+  mov    rdi, rsp
+  mov    rsi, array_len
+  call   bogo_sort
+  # Print the sorted array
+  mov    rdi, OFFSET sorted
+  xor    rax, rax
+  call   printf
+  mov    rdi, rsp
+  mov    rsi, array_len
+  call   print_array
+  # Restore the stack pointer, set return value to 0
+  add    rsp, 40
+  xor    rax, rax
+  ret
+