user: 请从给定的汇编指令推导出C源代码：

```asm
<lubksb>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  mov    %rdi,-0x28(%rbp)
  mov    %esi,-0x2c(%rbp)
  mov    %rdx,-0x38(%rbp)
  mov    %rcx,-0x40(%rbp)
  movl   $0x0,-0x10(%rbp)
  movl   $0x1,-0x14(%rbp)
  jmp    L11
L117:
  mov    -0x14(%rbp),%eax
  cltq
  lea    0x0(,%rax,4),%rdx
  mov    -0x38(%rbp),%rax
  add    %rdx,%rax
  mov    (%rax),%eax
  mov    %eax,-0x4(%rbp)
  mov    -0x4(%rbp),%eax
  cltq
  lea    0x0(,%rax,4),%rdx
  mov    -0x40(%rbp),%rax
  add    %rdx,%rax
  movss  (%rax),%xmm0
  movss  %xmm0,-0x8(%rbp)
  mov    -0x14(%rbp),%eax
  cltq
  lea    0x0(,%rax,4),%rdx
  mov    -0x40(%rbp),%rax
  add    %rax,%rdx
  mov    -0x4(%rbp),%eax
  cltq
  lea    0x0(,%rax,4),%rcx
  mov    -0x40(%rbp),%rax
  add    %rcx,%rax
  movss  (%rdx),%xmm0
  movss  %xmm0,(%rax)
  cmpl   $0x0,-0x10(%rbp)
  je     L105
  mov    -0x10(%rbp),%eax
  mov    %eax,-0xc(%rbp)
  jmp    L101
L104:
  mov    -0x14(%rbp),%eax
  cltq
  lea    0x0(,%rax,8),%rdx
  mov    -0x28(%rbp),%rax
  add    %rdx,%rax
  mov    (%rax),%rdx
  mov    -0xc(%rbp),%eax
  cltq
  shl    $0x2,%rax
  add    %rdx,%rax
  movss  (%rax),%xmm1
  mov    -0xc(%rbp),%eax
  cltq
  lea    0x0(,%rax,4),%rdx
  mov    -0x40(%rbp),%rax
  add    %rdx,%rax
  movss  (%rax),%xmm0
  mulss  %xmm0,%xmm1
  movss  -0x8(%rbp),%xmm0
  subss  %xmm1,%xmm0
  movss  %xmm0,-0x8(%rbp)
  addl   $0x1,-0xc(%rbp)
L101:
  mov    -0x14(%rbp),%eax
  cmp    -0xc(%rbp),%eax
  jg     L104
  jmp    L116
L105:
  pxor   %xmm0,%xmm0
  ucomiss -0x8(%rbp),%xmm0
  jp     L107
  pxor   %xmm0,%xmm0
  ucomiss -0x8(%rbp),%xmm0
  je     L116
L107:
  mov    -0x14(%rbp),%eax
  mov    %eax,-0x10(%rbp)
L116:
  mov    -0x14(%rbp),%eax
  cltq
  lea    0x0(,%rax,4),%rdx
  mov    -0x40(%rbp),%rax
  add    %rdx,%rax
  movss  -0x8(%rbp),%xmm0
  movss  %xmm0,(%rax)
  addl   $0x1,-0x14(%rbp)
L11:
  mov    -0x14(%rbp),%eax
  cmp    -0x2c(%rbp),%eax
  jle    L117
  mov    -0x2c(%rbp),%eax
  mov    %eax,-0x14(%rbp)
  jmp    L4
L17:
  mov    -0x14(%rbp),%eax
  cltq
  lea    0x0(,%rax,4),%rdx
  mov    -0x40(%rbp),%rax
  add    %rdx,%rax
  movss  (%rax),%xmm0
  movss  %xmm0,-0x8(%rbp)
  mov    -0x14(%rbp),%eax
  add    $0x1,%eax
  mov    %eax,-0xc(%rbp)
  jmp    L31
L28:
  mov    -0x14(%rbp),%eax
  cltq
  lea    0x0(,%rax,8),%rdx
  mov    -0x28(%rbp),%rax
  add    %rdx,%rax
  mov    (%rax),%rdx
  mov    -0xc(%rbp),%eax
  cltq
  shl    $0x2,%rax
  add    %rdx,%rax
  movss  (%rax),%xmm1
  mov    -0xc(%rbp),%eax
  cltq
  lea    0x0(,%rax,4),%rdx
  mov    -0x40(%rbp),%rax
  add    %rdx,%rax
  movss  (%rax),%xmm0
  mulss  %xmm0,%xmm1
  movss  -0x8(%rbp),%xmm0
  subss  %xmm1,%xmm0
  movss  %xmm0,-0x8(%rbp)
  addl   $0x1,-0xc(%rbp)
L31:
  mov    -0xc(%rbp),%eax
  cmp    -0x2c(%rbp),%eax
  jle    L28
  mov    -0x14(%rbp),%eax
  cltq
  lea    0x0(,%rax,8),%rdx
  mov    -0x28(%rbp),%rax
  add    %rdx,%rax
  mov    (%rax),%rdx
  mov    -0x14(%rbp),%eax
  cltq
  shl    $0x2,%rax
  add    %rdx,%rax
  movss  (%rax),%xmm1
  mov    -0x14(%rbp),%eax
  cltq
  lea    0x0(,%rax,4),%rdx
  mov    -0x40(%rbp),%rax
  add    %rdx,%rax
  movss  -0x8(%rbp),%xmm0
  divss  %xmm1,%xmm0
  movss  %xmm0,(%rax)
  subl   $0x1,-0x14(%rbp)
L4:
  cmpl   $0x0,-0x14(%rbp)
  jg     L17
  nop
  nop
  pop    %rbp
  ret
```

assistant: ```c
void lubksb(a, n, indx, b) float **a, b[];
int n, *indx;
{
  int i, ii = 0, ip, j;
  float sum;
  for (i = 1; i <= n; i++) {
    ip = indx[i];
    sum = b[ip];
    b[ip] = b[i];
    if (ii)
      for (j = ii; j <= i - 1; j++)
        sum -= a[i][j] * b[j];
    else if (sum)
      ii = i;
    b[i] = sum;
  }
  for (i = n; i >= 1; i--) {
    sum = b[i];
    for (j = i + 1; j <= n; j++)
      sum -= a[i][j] * b[j];
    b[i] = sum / a[i][i];
  }
}
```