user: Converte this assembly snippet into its equivalent C code:

```asm
<slice>:
  endbr64
  cmp    %edx,%esi
  jg     L137
  push   %r13
  push   %r12
  mov    %esi,%r12d
  push   %rbp
  mov    %rdi,%rbp
  push   %rbx
  mov    %edx,%ebx
  sub    $0x8,%rsp
  call   <str_length@plt>
  cmp    %ebx,%eax
  jl     L94
  sub    %r12d,%ebx
  lea    0x1(%rbx),%r13d
  mov    %r13d,%edi
  call   <malloc@plt>
  mov    %rax,%r8
  test   %rax,%rax
  je     L94
  movslq %r12d,%rdx
  mov    %rax,%rcx
  lea    0x1(%rbp,%rdx,1),%rsi
  sub    %rsi,%rcx
  cmp    $0xe,%rcx
  jbe    L174
  cmp    $0x6,%ebx
  jbe    L174
  cmp    $0xe,%ebx
  jbe    L188
  mov    %r13d,%esi
  mov    %rdx,%rdi
  mov    %rax,%rcx
  shr    $0x4,%esi
  sub    %rax,%rdi
  shl    $0x4,%rsi
  add    %rbp,%rdi
  add    %rax,%rsi
  nopl   0x0(%rax)
L20:
  movdqu (%rcx,%rdi,1),%xmm0
  add    $0x10,%rcx
  movups %xmm0,-0x10(%rcx)
  cmp    %rsi,%rcx
  jne    L20
  mov    %r13d,%esi
  and    $0xfffffff0,%esi
  mov    %esi,%ecx
  cmp    %esi,%r13d
  je     L141
  mov    %ebx,%edi
  sub    %esi,%edi
  lea    0x1(%rdi),%r13d
  cmp    $0x6,%edi
  jbe    L18
L25:
  add    %rbp,%rdx
  mov    (%rdx,%rsi,1),%rdx
  mov    %rdx,(%rax,%rsi,1)
  mov    %r13d,%edx
  and    $0xfffffff8,%edx
  add    %edx,%ecx
  cmp    %edx,%r13d
  je     L141
L18:
  lea    (%r12,%rcx,1),%edx
  movslq %edx,%rdx
  movzbl 0x0(%rbp,%rdx,1),%esi
  movslq %ecx,%rdx
  mov    %sil,(%rax,%rdx,1)
  lea    0x1(%rcx),%edx
  cmp    %edx,%ebx
  jl     L141
  lea    (%r12,%rdx,1),%esi
  movslq %edx,%rdx
  movslq %esi,%rsi
  movzbl 0x0(%rbp,%rsi,1),%esi
  mov    %sil,(%rax,%rdx,1)
  lea    0x2(%rcx),%edx
  cmp    %edx,%ebx
  jl     L141
  lea    (%r12,%rdx,1),%esi
  movslq %edx,%rdx
  movslq %esi,%rsi
  movzbl 0x0(%rbp,%rsi,1),%esi
  mov    %sil,(%rax,%rdx,1)
  lea    0x3(%rcx),%edx
  cmp    %edx,%ebx
  jl     L141
  lea    (%r12,%rdx,1),%esi
  movslq %edx,%rdx
  movslq %esi,%rsi
  movzbl 0x0(%rbp,%rsi,1),%esi
  mov    %sil,(%rax,%rdx,1)
  lea    0x4(%rcx),%edx
  cmp    %edx,%ebx
  jl     L141
  lea    (%r12,%rdx,1),%esi
  movslq %edx,%rdx
  movslq %esi,%rsi
  movzbl 0x0(%rbp,%rsi,1),%esi
  mov    %sil,(%rax,%rdx,1)
  lea    0x5(%rcx),%edx
  cmp    %edx,%ebx
  jl     L141
  lea    (%r12,%rdx,1),%esi
  add    $0x6,%ecx
  movslq %edx,%rdx
  movslq %esi,%rsi
  movzbl 0x0(%rbp,%rsi,1),%esi
  mov    %sil,(%rax,%rdx,1)
  cmp    %ecx,%ebx
  jl     L141
  add    %ecx,%r12d
  movslq %ecx,%rcx
  movslq %r12d,%r12
  movzbl 0x0(%rbp,%r12,1),%edx
  mov    %dl,(%rax,%rcx,1)
  add    $0x8,%rsp
  mov    %r8,%rax
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  ret
L94:
  xor    %r8d,%r8d
L141:
  add    $0x8,%rsp
  mov    %r8,%rax
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  ret
  nopl   0x0(%rax)
L137:
  xor    %eax,%eax
  ret
  nopl   0x0(%rax,%rax,1)
L174:
  movslq %ebx,%rbx
  sub    %rax,%rdx
  lea    0x1(%rax,%rbx,1),%rsi
  add    %rbp,%rdx
  xchg   %ax,%ax
L98:
  movzbl (%rdx,%rax,1),%ecx
  add    $0x1,%rax
  mov    %cl,-0x1(%rax)
  cmp    %rsi,%rax
  jne    L98
  jmp    L141
L188:
  xor    %esi,%esi
  xor    %ecx,%ecx
  jmp    L25
```

assistant: ```c
char *slice(char *s, int b, int e) {
  int i;
  char *slice;
  if (b > e || e > str_length(s)) {
    return NULL;
  }
  if ((slice = (char *)malloc(e - b + 1)) == NULL) {
    return NULL;
  }
  for (i = 0; i < e - b + 1; i++) {
    slice[i] = s[b + i];
  }
  return slice;
}
```