user: Converte this assembly snippet into its equivalent C code:

```asm
<solve>:
  endbr64
  push   %r15
  mov    %esi,%r15d
  push   %r14
  push   %r13
  push   %r12
  mov    %esi,%r12d
  push   %rbp
  mov    %rdi,%rbp
  push   %rbx
  movslq %edx,%rbx
  imul   %ebx,%r12d
  sub    $0x18,%rsp
  shl    $0x2,%r12d
  mov    %r12d,%edi
  call   <malloc@plt>
  mov    %r12d,%edi
  mov    %rax,%r13
  call   <malloc@plt>
  test   %r15d,%r15d
  jle    L187
  mov    %rax,%r14
  mov    %r15d,%eax
  mov    %rbp,(%rsp)
  mov    %rbp,%rdi
  mov    %rbp,0x8(%rsp)
  lea    -0x1(%r15),%r12d
  xor    %r10d,%r10d
  movslq %ebx,%r9
  mov    $0xffffffff,%ecx
  lea    -0x1(%rbx),%r15d
  mov    %eax,%ebp
  nopl   0x0(%rax)
L227:
  test   %ebx,%ebx
  jle    L312
  test   %r10d,%r10d
  sete   %r8b
  xor    %eax,%eax
  cmp    %r10d,%r12d
  jne    L82
  jmp    L242
  nopl   0x0(%rax)
L289:
  cmp    %r15d,%eax
  je     L219
L176:
  add    $0x1,%rax
  cmp    %rax,%r9
  je     L312
L82:
  mov    %eax,%esi
  test   %eax,%eax
  je     L219
  test   %r8b,%r8b
  je     L289
L219:
  mov    (%rdi),%rdx
  add    %rax,%rdx
  cmpb   $0x4f,(%rdx)
  jne    L176
  add    $0x1,%ecx
  add    $0x1,%rax
  movslq %ecx,%r11
  mov    %r10d,0x0(%r13,%r11,4)
  mov    %esi,(%r14,%r11,4)
  movb   $0x61,(%rdx)
  cmp    %rax,%r9
  jne    L82
  nopw   0x0(%rax,%rax,1)
L312:
  lea    0x1(%r10),%eax
  add    $0x8,%rdi
  cmp    %eax,%ebp
  je     L148
  mov    %eax,%r10d
  jmp    L227
  nopl   (%rax)
L270:
  add    $0x1,%ecx
  movslq %ecx,%rsi
  mov    %r10d,0x0(%r13,%rsi,4)
  mov    %eax,(%r14,%rsi,4)
  movb   $0x61,(%rdx)
L324:
  add    $0x1,%rax
  cmp    %r9,%rax
  je     L312
L242:
  mov    (%rdi),%rdx
  add    %rax,%rdx
  cmpb   $0x4f,(%rdx)
  jne    L324
  jmp    L270
L329:
  test   %ebx,%ebx
  jle    L187
  lea    0x8(%rbp,%r10,8),%rsi
  nopl   0x0(%rax)
L199:
  xor    %eax,%eax
  nopw   0x0(%rax,%rax,1)
L182:
  mov    (%rdx),%rcx
  add    %rax,%rcx
  cmpb   $0x61,(%rcx)
  je     L203
  add    $0x1,%rax
  movb   $0x58,(%rcx)
  cmp    %rbx,%rax
  jne    L182
  add    $0x8,%rdx
  cmp    %rdx,%rsi
  jne    L199
L187:
  add    $0x18,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
  nopl   0x0(%rax,%rax,1)
L148:
  mov    (%rsp),%rdx
  mov    0x8(%rsp),%rbp
  cmp    $0xffffffff,%ecx
  je     L329
  movslq %ecx,%rax
  nopl   0x0(%rax)
L306:
  shl    $0x2,%rax
  lea    -0x1(%rcx),%r9d
  lea    0x0(%r13,%rax,1),%r12
  add    %r14,%rax
  mov    (%r12),%edi
  mov    (%rax),%esi
  lea    0x1(%rdi),%r15d
  cmp    %r10d,%edi
  jge    L180
  movslq %edi,%r11
  movslq %esi,%r8
  add    0x8(%rbp,%r11,8),%r8
  cmpb   $0x4f,(%r8)
  jne    L180
  movb   $0x61,(%r8)
  mov    %ecx,%r9d
  mov    %r15d,(%r12)
  mov    %esi,(%rax)
  nopl   (%rax)
L180:
  lea    0x1(%rsi),%eax
  cmp    %ebx,%eax
  jge    L318
  movslq %edi,%r11
  movslq %esi,%r8
  mov    0x0(%rbp,%r11,8),%rcx
  lea    0x1(%rcx,%r8,1),%rcx
  cmpb   $0x4f,(%rcx)
  jne    L318
  add    $0x1,%r9d
  movb   $0x61,(%rcx)
  movslq %r9d,%rcx
  mov    %edi,0x0(%r13,%rcx,4)
  mov    %eax,(%r14,%rcx,4)
  nopw   0x0(%rax,%rax,1)
L318:
  test   %edi,%edi
  jle    L282
  movslq %edi,%r11
  movslq %esi,%r8
  mov    -0x8(%rbp,%r11,8),%rax
  add    %r8,%rax
  cmpb   $0x4f,(%rax)
  je     L167
L282:
  mov    %r9d,%ecx
  test   %esi,%esi
  jle    L42
  movslq %edi,%r11
  movslq %esi,%r8
L34:
  mov    0x0(%rbp,%r11,8),%rax
  mov    %r9d,%ecx
  lea    -0x1(%rax,%r8,1),%rax
  cmpb   $0x4f,(%rax)
  je     L51
L42:
  cmp    $0xffffffff,%r9d
  je     L329
  movslq %r9d,%rax
  jmp    L306
  nopl   0x0(%rax,%rax,1)
L51:
  add    $0x1,%ecx
  movb   $0x61,(%rax)
  sub    $0x1,%esi
  movslq %ecx,%rax
  mov    %edi,0x0(%r13,%rax,4)
  mov    %esi,(%r14,%rax,4)
  jmp    L306
  nopw   0x0(%rax,%rax,1)
L167:
  add    $0x1,%r9d
  movb   $0x61,(%rax)
  lea    -0x1(%rdi),%ecx
  movslq %r9d,%rax
  mov    %ecx,0x0(%r13,%rax,4)
  mov    %r9d,%ecx
  mov    %esi,(%r14,%rax,4)
  test   %esi,%esi
  jg     L34
  jmp    L306
  nopw   0x0(%rax,%rax,1)
L203:
  add    $0x1,%rax
  movb   $0x4f,(%rcx)
  cmp    %rbx,%rax
  jne    L182
  add    $0x8,%rdx
  cmp    %rdx,%rsi
  jne    L199
  jmp    L187
```

assistant: ```c
void solve(char **board, int rSize, int cSize) {
  int *rStack = (int *)malloc(sizeof(int) * rSize * cSize);
  int *cStack = (int *)malloc(sizeof(int) * rSize * cSize);
  int top = -1;
  for (int i = 0; i < rSize; i++)
    for (int j = 0; j < cSize; j++) {
      if (i == 0 || j == 0 || i == rSize - 1 || j == cSize - 1) {
        if (board[i][j] == 'O') {
          rStack[++top] = i;
          cStack[top] = j;
          board[i][j] = 'a';
        }
      }
    }
  while (top > -1) {
    int r = rStack[top], c = cStack[top--];
    if (r + 1 < rSize && board[r + 1][c] == 'O') {
      board[r + 1][c] = 'a';
      rStack[++top] = r + 1;
      cStack[top] = c;
    }
    if (c + 1 < cSize && board[r][c + 1] == 'O') {
      board[r][c + 1] = 'a';
      rStack[++top] = r;
      cStack[top] = c + 1;
    }
    if (r - 1 > -1 && board[r - 1][c] == 'O') {
      board[r - 1][c] = 'a';
      rStack[++top] = r - 1;
      cStack[top] = c;
    }
    if (c - 1 > -1 && board[r][c - 1] == 'O') {
      board[r][c - 1] = 'a';
      rStack[++top] = r;
      cStack[top] = c - 1;
    }
  }
  for (int i = 0; i < rSize; i++) {
    for (int j = 0; j < cSize; j++) {
      if (board[i][j] == 'a')
        board[i][j] = 'O';
      else
        board[i][j] = 'X';
    }
  }
}
```