user: Please show me the C implementation that matches the assembly code listed below:

```asm
<lubksb>:
  endbr64
  mov    %rdi,%r11
  mov    %esi,%edi
  test   %esi,%esi
  jle    L5
  push   %r14
  mov    %rdx,%r10
  mov    $0x4,%esi
  mov    %rcx,%rdx
  push   %r13
  xor    %r8d,%r8d
  mov    $0x1,%eax
  pxor   %xmm2,%xmm2
  push   %r12
  push   %rbp
  push   %rbx
L238:
  movslq (%r10,%rsi,1),%rcx
  movss  (%rdx,%rsi,1),%xmm0
  lea    (%rdx,%rcx,4),%rcx
  movss  (%rcx),%xmm1
  movss  %xmm0,(%rcx)
  test   %r8d,%r8d
  jne    L195
  ucomiss %xmm2,%xmm1
  jp     L154
  je     L37
L154:
  mov    %eax,%r8d
L37:
  add    $0x1,%eax
  movss  %xmm1,(%rdx,%rsi,1)
  cmp    %eax,%edi
  jl     L82
  add    $0x4,%rsi
  jmp    L238
  nopw   0x0(%rax,%rax,1)
L195:
  cmp    %r8d,%eax
  jle    L56
  mov    %eax,%r12d
  mov    (%r11,%rsi,2),%r13
  sub    %r8d,%r12d
  lea    -0x1(%r12),%ecx
  cmp    $0x2,%ecx
  jbe    L185
  movslq %r8d,%r9
  mov    %r12d,%ebx
  xor    %ecx,%ecx
  shl    $0x2,%r9
  shr    $0x2,%ebx
  lea    0x0(%r13,%r9,1),%rbp
  shl    $0x4,%rbx
  add    %rdx,%r9
  nopl   0x0(%rax)
L170:
  movups 0x0(%rbp,%rcx,1),%xmm0
  movups (%r9,%rcx,1),%xmm4
  add    $0x10,%rcx
  mulps  %xmm4,%xmm0
  subss  %xmm0,%xmm1
  movaps %xmm0,%xmm2
  shufps $0x55,%xmm0,%xmm2
  subss  %xmm2,%xmm1
  movaps %xmm0,%xmm2
  unpckhps %xmm0,%xmm2
  shufps $0xff,%xmm0,%xmm0
  subss  %xmm2,%xmm1
  subss  %xmm0,%xmm1
  cmp    %rbx,%rcx
  jne    L170
  mov    %r12d,%r9d
  and    $0xfffffffc,%r9d
  lea    (%r9,%r8,1),%ecx
  cmp    %r9d,%r12d
  je     L56
L249:
  movslq %ecx,%rbx
  movss  0x0(%r13,%rbx,4),%xmm0
  mulss  (%rdx,%rbx,4),%xmm0
  lea    0x0(,%rbx,4),%r9
  lea    0x1(%rcx),%ebx
  subss  %xmm0,%xmm1
  cmp    %ebx,%eax
  jle    L56
  movss  0x4(%r13,%r9,1),%xmm0
  mulss  0x4(%rdx,%r9,1),%xmm0
  add    $0x2,%ecx
  subss  %xmm0,%xmm1
  cmp    %ecx,%eax
  jle    L56
  movss  0x8(%r13,%r9,1),%xmm0
  mulss  0x8(%rdx,%r9,1),%xmm0
  subss  %xmm0,%xmm1
L56:
  add    $0x1,%eax
  movss  %xmm1,(%rdx,%rsi,1)
  cmp    %eax,%edi
  jl     L82
  movslq %r8d,%r13
  movslq %eax,%rcx
  sub    %r8d,%eax
  shl    $0x2,%r13
  lea    (%rdx,%r13,1),%rbx
L259:
  movslq (%r10,%rcx,4),%rsi
  movss  (%rdx,%rcx,4),%xmm0
  mov    %ecx,%r12d
  lea    (%rdx,%rsi,4),%rsi
  movss  (%rsi),%xmm1
  movss  %xmm0,(%rsi)
  cmp    %ecx,%r8d
  jge    L168
  lea    -0x1(%rax),%esi
  mov    (%r11,%rcx,8),%r14
  cmp    $0x2,%esi
  jbe    L86
  mov    %eax,%r9d
  lea    (%r14,%r13,1),%rbp
  xor    %esi,%esi
  shr    $0x2,%r9d
  shl    $0x4,%r9
  nopw   0x0(%rax,%rax,1)
L7:
  movups 0x0(%rbp,%rsi,1),%xmm0
  movups (%rbx,%rsi,1),%xmm5
  add    $0x10,%rsi
  mulps  %xmm5,%xmm0
  subss  %xmm0,%xmm1
  movaps %xmm0,%xmm2
  shufps $0x55,%xmm0,%xmm2
  subss  %xmm2,%xmm1
  movaps %xmm0,%xmm2
  unpckhps %xmm0,%xmm2
  shufps $0xff,%xmm0,%xmm0
  subss  %xmm2,%xmm1
  subss  %xmm0,%xmm1
  cmp    %r9,%rsi
  jne    L7
  mov    %eax,%r9d
  and    $0xfffffffc,%r9d
  lea    (%r9,%r8,1),%esi
  cmp    %eax,%r9d
  je     L168
L87:
  movslq %esi,%rbp
  movss  (%rdx,%rbp,4),%xmm0
  mulss  (%r14,%rbp,4),%xmm0
  lea    0x0(,%rbp,4),%r9
  lea    0x1(%rsi),%ebp
  subss  %xmm0,%xmm1
  cmp    %r12d,%ebp
  jge    L168
  movss  0x4(%r14,%r9,1),%xmm0
  mulss  0x4(%rdx,%r9,1),%xmm0
  add    $0x2,%esi
  subss  %xmm0,%xmm1
  cmp    %r12d,%esi
  jge    L168
  movss  0x8(%r14,%r9,1),%xmm0
  mulss  0x8(%rdx,%r9,1),%xmm0
  subss  %xmm0,%xmm1
L168:
  movss  %xmm1,(%rdx,%rcx,4)
  add    $0x1,%rcx
  add    $0x1,%eax
  cmp    %ecx,%edi
  jge    L259
L82:
  movslq %edi,%rax
  lea    0x1(%rdi),%ebx
  xor    %esi,%esi
  lea    0x4(,%rax,4),%r12
  nopl   0x0(%rax,%rax,1)
L247:
  mov    %r12,%r10
  mov    %ebx,%eax
  sub    $0x4,%r12
  movss  -0x4(%rdx,%r10,1),%xmm1
  mov    -0x8(%r11,%r10,2),%rbp
  cmp    %ebx,%edi
  jl     L121
  lea    -0x1(%rsi),%ecx
  cmp    $0x2,%ecx
  jbe    L187
  mov    %esi,%ecx
  lea    0x0(%rbp,%r10,1),%r9
  lea    (%rdx,%r10,1),%r8
  xor    %eax,%eax
  shr    $0x2,%ecx
  shl    $0x4,%rcx
  nopl   0x0(%rax)
L184:
  movups (%r8,%rax,1),%xmm0
  movups (%r9,%rax,1),%xmm3
  add    $0x10,%rax
  mulps  %xmm3,%xmm0
  subss  %xmm0,%xmm1
  movaps %xmm0,%xmm2
  shufps $0x55,%xmm0,%xmm2
  subss  %xmm2,%xmm1
  movaps %xmm0,%xmm2
  unpckhps %xmm0,%xmm2
  shufps $0xff,%xmm0,%xmm0
  subss  %xmm2,%xmm1
  subss  %xmm0,%xmm1
  cmp    %rax,%rcx
  jne    L184
  mov    %esi,%ecx
  and    $0xfffffffc,%ecx
  lea    (%rbx,%rcx,1),%eax
  cmp    %esi,%ecx
  je     L121
L187:
  movslq %eax,%r8
  movss  0x0(%rbp,%r8,4),%xmm0
  mulss  (%rdx,%r8,4),%xmm0
  lea    0x0(,%r8,4),%rcx
  lea    0x1(%rax),%r8d
  subss  %xmm0,%xmm1
  cmp    %edi,%r8d
  jg     L121
  movss  0x4(%rbp,%rcx,1),%xmm0
  mulss  0x4(%rdx,%rcx,1),%xmm0
  add    $0x2,%eax
  subss  %xmm0,%xmm1
  cmp    %eax,%edi
  jl     L121
  movss  0x8(%rdx,%rcx,1),%xmm0
  mulss  0x8(%rbp,%rcx,1),%xmm0
  subss  %xmm0,%xmm1
L121:
  add    $0x1,%esi
  divss  0x0(%rbp,%r12,1),%xmm1
  sub    $0x1,%ebx
  movss  %xmm1,-0x4(%rdx,%r10,1)
  cmp    %esi,%edi
  jne    L247
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  ret
L185:
  mov    %r8d,%ecx
  jmp    L249
L86:
  mov    %r8d,%esi
  jmp    L87
L5:
  ret
```

assistant: ```c
void lubksb(float **a, int n, int *indx, float b[]) {
  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];
  }
}
```