user: What is the c source code of the assembly code below:

```asm
<mergesort>:
  endbr64
  push   %r15
  push   %r14
  mov    %edx,%r14d
  push   %r13
  mov    %ecx,%r13d
  push   %r12
  mov    %esi,%r12d
  push   %rbp
  lea    0x1(%rdx),%ebp
  push   %rbx
  mov    %rdi,%rbx
  lea    0x0(,%r8,4),%edi
  sub    $0x8,%rsp
  call   <malloc@plt>
  mov    %rax,%r8
  cmp    %r14d,%r12d
  jg     L248
  cmp    %r13d,%ebp
  jg     L248
  movslq %r12d,%r9
  mov    %r12d,%ecx
  mov    %r12d,%edx
  lea    (%rax,%r9,4),%rax
L101:
  movslq %ebp,%r10
  mov    (%rbx,%r9,4),%edi
  add    $0x1,%ecx
  mov    (%rbx,%r10,4),%esi
  cmp    %edi,%esi
  jle    L279
L39:
  mov    %edi,(%rax)
  add    $0x1,%edx
  add    $0x4,%rax
  cmp    %ebp,%r13d
  jl     L161
  cmp    %edx,%r14d
  jl     L267
  movslq %edx,%r9
  mov    (%rbx,%r10,4),%esi
  add    $0x1,%ecx
  mov    (%rbx,%r9,4),%edi
  cmp    %edi,%esi
  jg     L39
L279:
  mov    %esi,(%rax)
  add    $0x1,%ebp
  add    $0x4,%rax
  cmp    %r14d,%edx
  jg     L267
  cmp    %ebp,%r13d
  jge    L101
L161:
  cmp    %edx,%r14d
  jl     L90
  movslq %ecx,%r11
  movslq %edx,%r10
  mov    %r14d,%edi
  lea    0x0(,%r11,4),%r9
  lea    0x4(,%r10,4),%r10
  sub    %edx,%edi
  lea    (%r9,%r8,1),%rsi
  lea    (%rbx,%r10,1),%r15
  mov    %rsi,%rbp
  mov    %rsi,%rax
  sub    %r15,%rbp
  cmp    $0x8,%rbp
  jbe    L38
  cmp    $0x2,%edi
  jbe    L38
  lea    0x1(%rdi),%esi
  mov    %esi,%edi
  shr    $0x2,%edi
  sub    $0x1,%edi
  shl    $0x4,%rdi
  lea    0x10(%rax,%rdi,1),%r9
  mov    %rbx,%rdi
  sub    %rax,%rdi
  lea    -0x4(%rdi,%r10,1),%rdi
  nopl   0x0(%rax)
L336:
  movdqu (%rax,%rdi,1),%xmm2
  add    $0x10,%rax
  movups %xmm2,-0x10(%rax)
  cmp    %r9,%rax
  jne    L336
  mov    %esi,%eax
  and    $0xfffffffc,%eax
  add    %eax,%ecx
  add    %eax,%edx
  cmp    %eax,%esi
  je     L90
  movslq %edx,%rax
  lea    0x1(%rcx),%esi
  movslq %ecx,%rcx
  mov    (%rbx,%rax,4),%eax
  mov    %eax,(%r8,%rcx,4)
  lea    0x1(%rdx),%eax
  cmp    %eax,%r14d
  jl     L90
  cltq
  movslq %esi,%rcx
  add    $0x2,%edx
  lea    0x0(,%rax,4),%rdi
  mov    (%rbx,%rax,4),%eax
  lea    0x0(,%rcx,4),%rsi
  mov    %eax,(%r8,%rcx,4)
  cmp    %r14d,%edx
  jg     L90
  mov    0x4(%rbx,%rdi,1),%eax
  mov    %eax,0x4(%r8,%rsi,1)
L90:
  cmp    %r13d,%r12d
  jg     L121
  movslq %r12d,%rax
  mov    %r13d,%edi
  lea    0x0(,%rax,4),%rdx
  sub    %r12d,%edi
  lea    (%rbx,%rdx,1),%rsi
  add    %r8,%rdx
  lea    0x4(%rdx),%rcx
  mov    %rsi,%r9
  sub    %rcx,%r9
  cmp    $0x8,%r9
  jbe    L353
  cmp    $0x2,%edi
  jbe    L353
  add    $0x1,%edi
  mov    %rsi,%rcx
  mov    %edi,%eax
  sub    %rdx,%rcx
  shr    $0x2,%eax
  shl    $0x4,%rax
  add    %rdx,%rax
  nopw   0x0(%rax,%rax,1)
L15:
  movdqu (%rdx),%xmm0
  movups %xmm0,(%rcx,%rdx,1)
  add    $0x10,%rdx
  cmp    %rdx,%rax
  jne    L15
  mov    %edi,%eax
  and    $0xfffffffc,%eax
  add    %eax,%r12d
  cmp    %edi,%eax
  je     L121
  movslq %r12d,%rax
  mov    (%r8,%rax,4),%edx
  mov    %edx,(%rbx,%rax,4)
  lea    0x1(%r12),%eax
  cmp    %r13d,%eax
  jg     L121
  cltq
  add    $0x2,%r12d
  mov    (%r8,%rax,4),%ecx
  lea    0x0(,%rax,4),%rdx
  mov    %ecx,(%rbx,%rax,4)
  cmp    %r13d,%r12d
  jg     L121
  mov    0x4(%r8,%rdx,1),%eax
  mov    %eax,0x4(%rbx,%rdx,1)
L121:
  add    $0x8,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
  nopl   0x0(%rax,%rax,1)
L248:
  mov    %r12d,%ecx
  mov    %r12d,%edx
  xchg   %ax,%ax
L267:
  cmp    %ebp,%r13d
  jl     L161
  movslq %ecx,%r10
  movslq %ebp,%r9
  mov    %r13d,%esi
  lea    0x0(,%r10,4),%rdi
  lea    0x4(,%r9,4),%r9
  sub    %ebp,%esi
  lea    (%rdi,%r8,1),%rdx
  lea    (%rbx,%r9,1),%r14
  mov    %rdx,%r11
  mov    %rdx,%rax
  sub    %r14,%r11
  cmp    $0x8,%r11
  jbe    L109
  cmp    $0x2,%esi
  jbe    L109
  lea    0x1(%rsi),%edx
  mov    %edx,%esi
  shr    $0x2,%esi
  sub    $0x1,%esi
  shl    $0x4,%rsi
  lea    0x10(%rax,%rsi,1),%rdi
  mov    %rbx,%rsi
  sub    %rax,%rsi
  lea    -0x4(%rsi,%r9,1),%rsi
  nopw   0x0(%rax,%rax,1)
L30:
  movdqu (%rax,%rsi,1),%xmm1
  add    $0x10,%rax
  movups %xmm1,-0x10(%rax)
  cmp    %rdi,%rax
  jne    L30
  mov    %edx,%eax
  and    $0xfffffffc,%eax
  add    %eax,%ecx
  add    %eax,%ebp
  cmp    %eax,%edx
  je     L90
  movslq %ebp,%rax
  lea    0x1(%rcx),%edx
  movslq %ecx,%rcx
  mov    (%rbx,%rax,4),%eax
  mov    %eax,(%r8,%rcx,4)
  lea    0x1(%rbp),%eax
  cmp    %eax,%r13d
  jl     L90
  cltq
  movslq %edx,%rdx
  add    $0x2,%ebp
  lea    0x0(,%rax,4),%rsi
  mov    (%rbx,%rax,4),%eax
  lea    0x0(,%rdx,4),%rcx
  mov    %eax,(%r8,%rdx,4)
  cmp    %ebp,%r13d
  jl     L90
  mov    0x4(%rbx,%rsi,1),%eax
  mov    %eax,0x4(%r8,%rcx,1)
  jmp    L90
  nopl   (%rax)
L109:
  mov    %esi,%eax
  add    %r10,%rax
  lea    0x4(%r8,%rax,4),%rsi
  lea    -0x4(%r9),%rax
  sub    %rdi,%rax
  sub    %r8,%rax
  add    %rbx,%rax
  nop
L328:
  mov    (%rax,%rdx,1),%ecx
  add    $0x4,%rdx
  mov    %ecx,-0x4(%rdx)
  cmp    %rsi,%rdx
  jne    L328
  jmp    L90
  nopl   0x0(%rax)
L353:
  lea    0x1(%rax,%rdi,1),%rax
  lea    (%r8,%rax,4),%rdi
  mov    %rbx,%rax
  sub    %r8,%rax
  jmp    L187
  nopl   0x0(%rax)
L5:
  add    $0x4,%rcx
L187:
  mov    (%rdx),%esi
  mov    %esi,(%rax,%rdx,1)
  mov    %rcx,%rdx
  cmp    %rcx,%rdi
  jne    L5
  add    $0x8,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
L38:
  lea    -0x4(%r10),%rax
  mov    %edi,%edx
  sub    %r9,%rax
  add    %r11,%rdx
  sub    %r8,%rax
  lea    0x4(%r8,%rdx,4),%rcx
  add    %rbx,%rax
  nopw   0x0(%rax,%rax,1)
L88:
  mov    (%rax,%rsi,1),%edx
  add    $0x4,%rsi
  mov    %edx,-0x4(%rsi)
  cmp    %rcx,%rsi
  jne    L88
  jmp    L90
```

assistant: ```c
void mergesort(int *a, int start, int mid, int end, int size) {
  int i = start, begin = start, m = mid + 1, k, *b;
  b = (int *)malloc(sizeof(int) * size);
  while (start <= mid && m <= end) {
    if (a[start] < a[m]) {
      b[i] = a[start];
      start++;
      i++;
    } else {
      b[i] = a[m];
      m++;
      i++;
    }
  }
  if (m > end) {
    for (k = start; k <= mid; k++)
      b[i++] = a[k];
  } else {
    for (k = m; k <= end; k++)
      b[i++] = a[k];
  }
  for (i = begin; i <= end; i++) {
    a[i] = b[i];
  }
}
```