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

```asm
<Gauss_siedel>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  sub    $0x18,%rsp
  mov    %rdi,(%rsp)
  mov    %rsi,0x8(%rsp)
  mov    %rdx,%rbp
  mov    %rcx,%rbx
  mov    $0x0,%r12d
  jmp    L93
L16:
  add    $0x1,%rdx
  add    $0x8,%rcx
  add    $0x8,%rax
  add    $0x8,%rsi
  cmp    %r10,%rdx
  je     L88
L37:
  test   $0x1,%dl
  jne    L16
  movsd  (%rcx),%xmm0
  mulsd  (%rax),%xmm0
  movsd  0x8(%rcx),%xmm1
  mulsd  0x10(%rax),%xmm1
  addsd  %xmm1,%xmm0
  movsd  (%rsi),%xmm1
  mulsd  -0x958(%rax),%xmm1
  addsd  %xmm1,%xmm0
  movsd  0x950(%rsi),%xmm1
  mulsd  0x968(%rax),%xmm1
  addsd  %xmm1,%xmm0
  movsd  (%r11,%rdx,8),%xmm1
  subsd  %xmm0,%xmm1
  movsd  %xmm1,0x8(%rax)
  xorpd  D2(%rip),%xmm1
  movsd  0x8(%rcx),%xmm0
  addsd  (%rcx),%xmm0
  addsd  0x950(%rsi),%xmm0
  addsd  (%rsi),%xmm0
  divsd  %xmm0,%xmm1
  movsd  %xmm1,0x8(%rax)
  jmp    L16
L88:
  add    $0x1,%r10
  add    $0x958,%r11
  add    $0x12a,%r13
  add    $0x958,%r14
  add    $0x960,%r15
  cmp    $0x15ae4,%r13
  je     L47
L60:
  lea    -0x12a(%r10),%rdx
  lea    (%rbx,%r13,8),%rsi
  mov    %r15,%rax
  mov    %r14,%rcx
  jmp    L37
L82:
  add    $0x1,%rdx
  add    $0x8,%rcx
  add    $0x8,%rax
  add    $0x8,%rsi
  cmp    %r10,%rdx
  je     L10
L69:
  test   $0x1,%dl
  je     L82
  movsd  (%rcx),%xmm0
  mulsd  (%rax),%xmm0
  movsd  0x8(%rcx),%xmm1
  mulsd  0x10(%rax),%xmm1
  addsd  %xmm1,%xmm0
  movsd  (%rsi),%xmm1
  mulsd  -0x958(%rax),%xmm1
  addsd  %xmm1,%xmm0
  movsd  0x950(%rsi),%xmm1
  mulsd  0x968(%rax),%xmm1
  addsd  %xmm1,%xmm0
  movsd  (%rdi,%rdx,8),%xmm1
  subsd  %xmm0,%xmm1
  movsd  %xmm1,0x8(%rax)
  xorpd  D2(%rip),%xmm1
  movsd  (%rcx),%xmm0
  addsd  0x8(%rcx),%xmm0
  addsd  (%rsi),%xmm0
  addsd  0x950(%rsi),%xmm0
  divsd  %xmm0,%xmm1
  movsd  %xmm1,0x8(%rax)
  jmp    L82
L10:
  add    $0x1,%r10
  add    $0x958,%rdi
  add    $0x12a,%r11
  add    $0x958,%r9
  add    $0x960,%r8
  cmp    $0x15ae4,%r11
  je     L15
L138:
  lea    -0x12a(%r10),%rdx
  lea    (%rbx,%r11,8),%rsi
  mov    %r8,%rax
  mov    %r9,%rcx
  jmp    L69
L47:
  mov    $0x0,%r11d
  mov    $0x12c,%r10d
  jmp    L138
L15:
  add    $0x1,%r12d
  mov    0x8(%rsp),%rcx
  mov    (%rsp),%rdx
  mov    %rbx,%rsi
  mov    %rbp,%rdi
  call   <compute_error@plt>
  movq   %xmm0,%r13
  mov    %r12d,%esi
  lea    D4(%rip),%rdi
  call   <printf@plt>
  movq   %r13,%xmm0
  andpd  D46(%rip),%xmm0
  movsd  D40(%rip),%xmm1
  comisd %xmm0,%xmm1
  ja     L71
L93:
  mov    $0x0,%eax
  call   <boundary_pressure@plt>
  mov    0x8(%rsp),%rax
  lea    0x958(%rax),%rdi
  mov    %rbp,%r9
  mov    (%rsp),%rax
  lea    0x960(%rax),%r8
  mov    %r8,%r15
  mov    %rbp,%r14
  mov    %rdi,%r11
  mov    $0x0,%r13d
  mov    $0x12c,%r10d
  jmp    L60
L71:
  add    $0x18,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
```

tool_calls: name: extract_symbolic_data
arguments: data_label: D2
type: byte[16]
name: extract_symbolic_data
arguments: data_label: D4
type: string
name: extract_symbolic_data
arguments: data_label: D46
type: qword[2]
name: extract_symbolic_data
arguments: data_label: D40
type: byte[8]

tool: {"D2": [0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x80,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00]}

tool: D4: iter=%d	error=%lf


tool: {"D46": [0x7fffffffffffffff,0x0000000000000000]}

tool: {"D40": [0x8d,0xed,0xb5,0xa0,0xf7,0xc6,0xb0,0x3e]}

assistant: ```c
void Gauss_siedel(double *P, double *fn, double *a_x, double *a_y) {
  long i, j, indx, indx_rght, indx_frnt, indx_lft, indx_bck, indx_ax, indx_ay;
  double P_old;
  double error;
  double tol = 1.0e-6;
  int iter = 0;
  for (;;) {
    boundary_pressure();
    for (i = 1; i < 300 - 1; i++) {
      for (j = 1; j < 300 - 1; j++) {
        indx = i * 300 + j;
        indx_rght = indx + 1;
        indx_frnt = indx + 300;
        indx_lft = indx - 1;
        indx_bck = indx - 300;
        indx_ax = (i - 1) * (300 - 1) + (j - 1);
        indx_ay = (i - 1) * (300 - 2) + (j - 1);
        if (((i + j) % 2) == 0) {
          P[indx] = -1.0 * (a_x[indx_ax] * P[indx_lft] + a_x[indx_ax + 1] * P[indx_rght] + a_y[indx_ay] * P[indx_bck] + a_y[indx_ay + (300 - 2)] * P[indx_frnt]) + 1.0 * 1.0 * fn[indx];
          P[indx] /= -1.0 * (a_x[indx_ax + 1] + a_x[indx_ax] + a_y[indx_ay + (300 - 2)] + a_y[indx_ay]);
        }
      }
    }
    for (i = 1; i < 300 - 1; i++) {
      for (j = 1; j < 300 - 1; j++) {
        indx = i * 300 + j;
        indx_rght = indx + 1;
        indx_frnt = indx + 300;
        indx_lft = indx - 1;
        indx_bck = indx - 300;
        indx_ax = (i - 1) * (300 - 1) + (j - 1);
        indx_ay = (i - 1) * (300 - 2) + (j - 1);
        if (((i + j) % 2) != 0) {
          P[indx] = -1.0 * (a_x[indx_ax] * P[indx_lft] + a_x[indx_ax + 1] * P[indx_rght] + a_y[indx_ay] * P[indx_bck] + a_y[indx_ay + (300 - 2)] * P[indx_frnt]) + 1.0 * 1.0 * fn[indx];
          P[indx] /= -1.0 * (a_x[indx_ax] + a_x[indx_ax + 1] + a_y[indx_ay] + a_y[indx_ay + (300 - 2)]);
        }
      }
    }
    iter++;
    error = compute_error(a_x, a_y, P, fn);
    printf("iter=%d\terror=%lf\n", iter, error);
    if (fabs(error) < tol) {
      break;
    }
  }
}
```