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

```asm
<covsrt>:
  endbr64
  push   %r13
  mov    %rdx,%r9
  mov    %ecx,%r8d
  push   %r12
  push   %rbp
  push   %rbx
  cmp    $0x1,%esi
  jle    L163
  lea    0x1(%rsi),%r11d
  mov    $0x4,%ecx
  mov    $0x2,%r10d
  nopl   0x0(%rax,%rax,1)
L106:
  mov    %r10,%rax
  cmp    %r10d,%esi
  jl     L50
  nopl   0x0(%rax,%rax,1)
L236:
  mov    (%rdi,%rax,8),%rdx
  add    $0x1,%rax
  movl   $0x0,(%rdx,%rcx,1)
  cmp    %eax,%esi
  jge    L236
L50:
  add    $0x1,%r10
  add    $0x4,%rcx
  cmp    %r10,%r11
  jne    L106
  mov    0x8(%rdi),%rcx
  mov    %rcx,%r13
  cmp    $0x1,%r8d
  jle    L17
L185:
  mov    $0x2,%ebp
  cs nopw 0x0(%rax,%rax,1)
L145:
  cmp    %ebp,%r8d
  jl     L131
  movslq -0x4(%r9,%rbp,4),%rbx
  mov    -0x8(%rdi,%rbp,8),%r11
  mov    %rbp,%rax
  mov    %rbx,%r10
  lea    (%rdi,%rbx,8),%r12
  shl    $0x2,%rbx
  jmp    L91
  nop
L222:
  mov    (%rdi,%rcx,8),%rdx
  add    $0x1,%rax
  movss  %xmm0,(%rdx,%rbx,1)
  cmp    %eax,%r8d
  jl     L131
L91:
  movslq (%r9,%rax,4),%rcx
  movss  (%r11,%rax,4),%xmm0
  cmp    %r10d,%ecx
  jg     L222
  mov    (%r12),%rdx
  add    $0x1,%rax
  movss  %xmm0,(%rdx,%rcx,4)
  cmp    %eax,%r8d
  jge    L91
L131:
  add    $0x1,%rbp
  lea    -0x1(%rbp),%eax
  cmp    %eax,%r8d
  jg     L145
  movss  0x4(%r13),%xmm1
  mov    %r13,%rcx
  test   %esi,%esi
  jle    L230
L64:
  mov    $0x1,%eax
  nopl   (%rax)
L103:
  mov    (%rdi,%rax,8),%rdx
  lea    (%rdx,%rax,4),%rdx
  movss  (%rdx),%xmm0
  movss  %xmm0,(%rcx,%rax,4)
  add    $0x1,%rax
  movl   $0x0,(%rdx)
  cmp    %eax,%esi
  jge    L103
  movslq 0x4(%r9),%rax
  mov    (%rdi,%rax,8),%rdx
  movss  %xmm1,(%rdx,%rax,4)
  cmp    $0x1,%r8d
  jle    L238
L111:
  lea    0x1(%r8),%r10d
  mov    $0x2,%eax
  nopl   0x0(%rax,%rax,1)
L174:
  movslq (%r9,%rax,4),%rdx
  movss  (%rcx,%rax,4),%xmm0
  add    $0x1,%rax
  mov    (%rdi,%rdx,8),%r8
  movss  %xmm0,(%r8,%rdx,4)
  cmp    %rax,%r10
  jne    L174
L238:
  lea    0x1(%rsi),%r9d
  mov    $0x2,%ecx
  cmp    $0x1,%esi
  jle    L71
  nopw   0x0(%rax,%rax,1)
L186:
  mov    (%rdi,%rcx,8),%r8
  lea    0x0(,%rcx,4),%rsi
  mov    $0x1,%eax
  nopl   0x0(%rax)
L180:
  movss  (%r8,%rax,4),%xmm0
  mov    (%rdi,%rax,8),%rdx
  add    $0x1,%rax
  movss  %xmm0,(%rdx,%rsi,1)
  cmp    %rcx,%rax
  jne    L180
  add    $0x1,%rcx
  cmp    %rcx,%r9
  jne    L186
L71:
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  ret
L163:
  cmp    $0x1,%ecx
  jle    L139
  mov    0x8(%rdi),%r13
  jmp    L185
L230:
  movslq 0x4(%r9),%rax
  mov    (%rdi,%rax,8),%rdx
  movss  %xmm1,(%rdx,%rax,4)
  jmp    L111
L17:
  movss  0x4(%rcx),%xmm1
  jmp    L64
L139:
  mov    0x8(%rdi),%rcx
  movss  0x4(%rcx),%xmm1
  cmp    $0x1,%esi
  je     L64
  movslq 0x4(%r9),%rax
  mov    (%rdi,%rax,8),%rdx
  movss  %xmm1,(%rdx,%rax,4)
  jmp    L71
```

assistant: ```c
void covsrt(covar, ma, lista, mfit) float **covar;
int ma, lista[], mfit;
{
  int i, j;
  float swap;
  for (j = 1; j < ma; j++)
    for (i = j + 1; i <= ma; i++)
      covar[i][j] = 0.0;
  for (i = 1; i < mfit; i++)
    for (j = i + 1; j <= mfit; j++) {
      if (lista[j] > lista[i])
        covar[lista[j]][lista[i]] = covar[i][j];
      else
        covar[lista[i]][lista[j]] = covar[i][j];
    }
  swap = covar[1][1];
  for (j = 1; j <= ma; j++) {
    covar[1][j] = covar[j][j];
    covar[j][j] = 0.0;
  }
  covar[lista[1]][lista[1]] = swap;
  for (j = 2; j <= mfit; j++)
    covar[lista[j]][lista[j]] = covar[1][j];
  for (j = 2; j <= ma; j++)
    for (i = 1; i <= j - 1; i++)
      covar[i][j] = covar[j][i];
}
```