user: 请将这段汇编代码片段转换成等效的C代码:

```asm
<u2h>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  sub    $0x5d0,%rsp
  mov    %rdi,-0x5a8(%rbp)
  mov    %rsi,-0x5b0(%rbp)
  mov    %edx,-0x5b4(%rbp)
  mov    %rcx,-0x5c0(%rbp)
  mov    %r8,-0x5c8(%rbp)
  mov    %fs:0x28,%rax
  mov    %rax,-0x8(%rbp)
  xor    %eax,%eax
  cmpl   $0x3,-0x5b4(%rbp)
  jle    L27
  cmpl   $0x4,-0x5b4(%rbp)
  jne    L4
  mov    -0x5b4(%rbp),%ecx
  mov    -0x5b0(%rbp),%rdx
  lea    -0x290(%rbp),%rsi
  mov    -0x5a8(%rbp),%rax
  mov    %rax,%rdi
  call   <lin_hg@plt>
  lea    -0x290(%rbp),%rax
  mov    $0x9,%esi
  mov    %rax,%rdi
  call   <trnm@plt>
  movl   $0x48,-0x59c(%rbp)
  jmp    L71
L91:
  mov    -0x59c(%rbp),%eax
  cltq
  pxor   %xmm0,%xmm0
  movsd  %xmm0,-0x290(%rbp,%rax,8)
  addl   $0x1,-0x59c(%rbp)
L71:
  cmpl   $0x50,-0x59c(%rbp)
  jle    L91
  lea    -0x570(%rbp),%rdx
  lea    -0x520(%rbp),%rsi
  lea    -0x290(%rbp),%rax
  mov    %rdx,%rcx
  mov    $0x9,%edx
  mov    %rax,%rdi
  call   <nullspace@plt>
  lea    -0x520(%rbp),%rcx
  mov    -0x5c0(%rbp),%rax
  mov    $0x48,%edx
  mov    %rcx,%rsi
  mov    %rax,%rdi
  call   <memcpy@plt>
  jmp    L35
L4:
  cmpq   $0x0,-0x5c8(%rbp)
  jne    L48
  mov    -0x5b4(%rbp),%eax
  cltq
  mov    %eax,%edx
  mov    %edx,%eax
  shl    $0x3,%eax
  add    %edx,%eax
  shl    $0x4,%eax
  mov    %eax,%edi
  call   <malloc@plt>
  mov    %rax,-0x598(%rbp)
  jmp    L96
L48:
  mov    -0x5c8(%rbp),%rax
  mov    %rax,-0x598(%rbp)
L96:
  lea    -0x570(%rbp),%rdi
  lea    -0x590(%rbp),%rcx
  mov    -0x5b4(%rbp),%edx
  mov    -0x5b0(%rbp),%rsi
  mov    -0x5a8(%rbp),%rax
  mov    %rdi,%r8
  mov    %rax,%rdi
  call   <normu@plt>
  lea    -0x570(%rbp),%r8
  lea    -0x590(%rbp),%rdi
  mov    -0x5b4(%rbp),%ecx
  mov    -0x5b0(%rbp),%rdx
  mov    -0x598(%rbp),%rsi
  mov    -0x5a8(%rbp),%rax
  mov    %r8,%r9
  mov    %rdi,%r8
  mov    %rax,%rdi
  call   <lin_hgN@plt>
  mov    -0x5b4(%rbp),%eax
  lea    (%rax,%rax,1),%edx
  mov    -0x598(%rbp),%rsi
  lea    -0x520(%rbp),%rax
  mov    $0x9,%ecx
  mov    %rax,%rdi
  call   <cov_mat@plt>
  lea    -0x290(%rbp),%rcx
  lea    -0x520(%rbp),%rax
  mov    $0x9,%edx
  mov    %rcx,%rsi
  mov    %rax,%rdi
  call   <lap_eig@plt>
  lea    -0x520(%rbp),%rcx
  mov    -0x5c0(%rbp),%rax
  mov    $0x48,%edx
  mov    %rcx,%rsi
  mov    %rax,%rdi
  call   <memcpy@plt>
  lea    -0x570(%rbp),%rdx
  lea    -0x590(%rbp),%rcx
  mov    -0x5c0(%rbp),%rax
  mov    %rcx,%rsi
  mov    %rax,%rdi
  call   <denormH@plt>
  cmpq   $0x0,-0x5c8(%rbp)
  jne    L35
  mov    -0x598(%rbp),%rax
  mov    %rax,%rdi
  call   <free@plt>
  jmp    L35
L27:
  nop
L35:
  mov    -0x8(%rbp),%rax
  sub    %fs:0x28,%rax
  je     L55
  call   <__stack_chk_fail@plt>
L55:
  leave
  ret
```

assistant: ```c
void u2h(const double *u, const int *inl, int len, double *H, double *buffer) {
  double A1[3], A2[3];
  double *Z, V[9 * 9], D[9];
  int i, nullspace_buff[2 * 9];
  if (len < 4) {
    return;
  } else if (len == 4) {
    double Z2[9 * 9];
    lin_hg(u, Z2, inl, len);
    trnm(Z2, 9);
    for (i = 9 * 8; i < 9 * 9; ++i) {
      Z2[i] = 0.0;
    }
    nullspace(Z2, V, 9, nullspace_buff);
    memcpy(H, V, 3 * 3 * sizeof(double));
  } else {
    if (!buffer) {
      Z = (double *)malloc(sizeof(double) * 9 * len * 2);
    } else {
      Z = buffer;
    }
    normu(u, inl, len, A1, A2);
    lin_hgN(u, Z, inl, len, A1, A2);
    cov_mat(V, Z, 2 * len, 9);
    lap_eig(V, D, 9);
    memcpy(H, V, 3 * 3 * sizeof(double));
    denormH(H, A1, A2);
    if (!buffer) {
      free(Z);
    }
  }
}
```