user: 请从给定的汇编指令推导出C源代码：

```asm
<kaczmarz>:
  endbr64
  push   %r15
  mov    %rdi,%r15
  push   %r14
  lea    0x0(,%rsi,8),%r14d
  push   %r13
  push   %r12
  push   %rbp
  mov    %esi,%ebp
  push   %rbx
  mov    %r8,%rbx
  sub    $0x18,%rsp
  cmp    %edx,%esi
  je     L51
  mov    %r9,0x8(%rsp)
  mov    %edx,%r12d
  mov    %ecx,(%rsp)
  jg     L8
  mov    %esi,%edi
  imul   %esi,%edi
  shl    $0x3,%edi
  call   <malloc@plt>
  mov    %r14d,%edi
  mov    %rax,%r13
  call   <malloc@plt>
  mov    (%rsp),%ecx
  mov    %ebp,%r9d
  mov    %r13,%r8
  mov    %rax,%r14
  mov    %r12d,%edx
  mov    %ebp,%esi
  mov    %r15,%rdi
  call   <relax_aat@plt>
  mov    %rbx,%r8
  mov    %r14,%r9
  mov    %ebp,%ecx
  mov    %ebp,%edx
  mov    %ebp,%esi
  mov    %r13,%rdi
  call   <iterate_kacz@plt>
  mov    %eax,%ebx
  cmp    $0xffffffff,%eax
  je     L57
  mov    0x8(%rsp),%r9
  mov    (%rsp),%ecx
  mov    %r14,%r8
  mov    %r12d,%edx
  mov    %ebp,%esi
  mov    %r15,%rdi
  call   <relax_atb@plt>
L57:
  test   %r13,%r13
  je     L46
  mov    %r13,%rdi
  call   <free@plt>
L46:
  test   %r14,%r14
  je     L34
  mov    %r14,%rdi
  call   <free@plt>
L34:
  add    $0x18,%rsp
  mov    %ebx,%eax
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
  nopw   0x0(%rax,%rax,1)
L8:
  mov    %edx,%edi
  imul   %edx,%edi
  shl    $0x3,%edi
  call   <malloc@plt>
  mov    %r14d,%edi
  mov    %rax,%r13
  call   <malloc@plt>
  mov    (%rsp),%ecx
  mov    %r12d,%r9d
  mov    %r13,%r8
  mov    %r12d,%edx
  mov    %ebp,%esi
  mov    %r15,%rdi
  mov    %rax,%r14
  call   <relax_ata@plt>
  mov    (%rsp),%ecx
  mov    %rbx,%r8
  mov    %r14,%r9
  mov    %r12d,%edx
  mov    %ebp,%esi
  mov    %r15,%rdi
  call   <relax_atb@plt>
  mov    0x8(%rsp),%r9
  mov    %r14,%r8
  mov    %r12d,%ecx
  mov    %r12d,%edx
  mov    %r12d,%esi
  mov    %r13,%rdi
  call   <iterate_kacz@plt>
  mov    %eax,%ebx
  jmp    L57
  nopw   0x0(%rax,%rax,1)
L51:
  mov    %r14d,%edx
  mov    %r8,%rsi
  mov    %r9,%rdi
  mov    %ecx,0x8(%rsp)
  mov    %r9,(%rsp)
  call   <memcpy@plt>
  mov    (%rsp),%r9
  mov    0x8(%rsp),%ecx
  mov    %rbx,%r8
  add    $0x18,%rsp
  mov    %ebp,%edx
  mov    %ebp,%esi
  mov    %r15,%rdi
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  jmp    1110 <iterate_kacz@plt>
```

assistant: ```c
int kaczmarz(double *A, int m, int n, int stride, double *b, double *x0) {
  double *C, *c;
  int err;
  err = 0;
  C = NULL;
  c = NULL;
  if (m == n) {
    memcpy(x0, b, m * sizeof b[0]);
    if ((err = iterate_kacz(A, m, n, stride, b, x0)) == -1) {
      err = -1;
      goto err_out;
    }
  } else if (m > n) {
    C = malloc(n * n * sizeof C[0]);
    c = malloc(m * sizeof c[0]);
    relax_ata(A, m, n, stride, C, n);
    relax_atb(A, m, n, stride, b, c);
    if ((err = iterate_kacz(C, n, n, n, c, x0)) == -1) {
      err = -1;
      goto err_out;
    }
  } else {
    C = malloc(m * m * sizeof C[0]);
    c = malloc(m * sizeof c[0]);
    relax_aat(A, m, n, stride, C, m);
    if ((err = iterate_kacz(C, m, m, m, b, c)) == -1) {
      err = -1;
      goto err_out;
    }
    relax_atb(A, m, n, stride, c, x0);
  }
err_out:
  if (C != NULL)
    free(C);
  if (c != NULL)
    free(c);
  return err;
}
```