user: Demonstrate the C code that generates the assembly output below:

```asm
<stb_hash_fast>:
  endbr64
  mov    %rdi,%rax
  test   %esi,%esi
  jle    L75
  test   %rdi,%rdi
  je     L75
  mov    %esi,%edx
  test   $0x1,%al
  je     L34
  cmp    $0x3,%esi
  jle    L109
  lea    -0x4(%rsi),%r8d
  shr    $0x2,%r8d
  lea    0x1(%r8),%ecx
  mov    %ecx,%ecx
  lea    (%rdi,%rcx,4),%rdi
L58:
  movzbl 0x1(%rax),%ecx
  shl    $0x8,%ecx
  movzbl (%rax),%r9d
  add    %r9d,%ecx
  add    %edx,%ecx
  mov    %ecx,%r9d
  shl    $0x10,%r9d
  movzbl 0x3(%rax),%edx
  shl    $0x8,%edx
  movzbl 0x2(%rax),%r10d
  add    %r10d,%edx
  shl    $0xb,%edx
  xor    %ecx,%edx
  mov    %r9d,%ecx
  xor    %edx,%ecx
  add    $0x4,%rax
  mov    %ecx,%edx
  shr    $0xb,%edx
  add    %ecx,%edx
  cmp    %rdi,%rax
  jne    L58
  neg    %r8d
  lea    -0x4(%rsi,%r8,4),%esi
  jmp    L109
L34:
  cmp    $0x3,%esi
  jle    L109
  lea    -0x4(%rsi),%r8d
  shr    $0x2,%r8d
  lea    0x1(%r8),%ecx
  mov    %ecx,%ecx
  lea    (%rdi,%rcx,4),%rdi
L136:
  movzbl 0x1(%rax),%ecx
  shl    $0x8,%ecx
  movzbl (%rax),%r9d
  add    %r9d,%ecx
  add    %edx,%ecx
  mov    %ecx,%r9d
  shl    $0x10,%r9d
  movzbl 0x3(%rax),%edx
  shl    $0x8,%edx
  movzbl 0x2(%rax),%r10d
  add    %r10d,%edx
  shl    $0xb,%edx
  xor    %ecx,%edx
  mov    %r9d,%ecx
  xor    %edx,%ecx
  add    $0x4,%rax
  mov    %ecx,%edx
  shr    $0xb,%edx
  add    %ecx,%edx
  cmp    %rdi,%rax
  jne    L136
  neg    %r8d
  lea    -0x4(%rsi,%r8,4),%esi
L109:
  cmp    $0x2,%esi
  je     L29
  cmp    $0x3,%esi
  je     L0
  cmp    $0x1,%esi
  je     L101
L33:
  lea    0x0(,%rdx,8),%eax
  xor    %eax,%edx
  mov    %edx,%eax
  shr    $0x5,%eax
  add    %edx,%eax
  mov    %eax,%edx
  shl    $0x4,%edx
  xor    %eax,%edx
  mov    %edx,%eax
  shr    $0x11,%eax
  add    %edx,%eax
  mov    %eax,%edx
  shl    $0x19,%edx
  xor    %eax,%edx
  mov    %edx,%eax
  shr    $0x6,%eax
  add    %edx,%eax
  ret
L0:
  movzbl 0x1(%rdi),%eax
  shl    $0x8,%eax
  movzbl (%rdi),%ecx
  add    %ecx,%eax
  add    %edx,%eax
  mov    %eax,%ecx
  shl    $0x10,%ecx
  movzbl 0x2(%rdi),%edx
  shl    $0x12,%edx
  xor    %edx,%eax
  xor    %ecx,%eax
  mov    %eax,%edx
  shr    $0xb,%edx
  add    %eax,%edx
  jmp    L33
L29:
  movzbl 0x1(%rdi),%eax
  shl    $0x8,%eax
  movzbl (%rdi),%ecx
  add    %ecx,%eax
  add    %edx,%eax
  mov    %eax,%edx
  shl    $0xb,%edx
  xor    %edx,%eax
  mov    %eax,%edx
  shr    $0x11,%edx
  add    %eax,%edx
  jmp    L33
L101:
  movzbl (%rdi),%eax
  add    %eax,%edx
  mov    %edx,%eax
  shl    $0xa,%eax
  xor    %edx,%eax
  mov    %eax,%edx
  shr    %edx
  add    %eax,%edx
  jmp    L33
L75:
  mov    $0x0,%eax
  ret
```

assistant: ```c
unsigned int stb_hash_fast(void *p, int len) {
  unsigned char *q = (unsigned char *)p;
  unsigned int hash = len;
  if (len <= 0 || q == NULL)
    return 0;
  if (((int)q & 1) == 0) {
    for (; len > 3; len -= 4) {
      unsigned int val;
      hash += ((q)[0] + ((q)[1] << 8));
      val = (((q + 2)[0] + ((q + 2)[1] << 8)) << 11);
      hash = (hash << 16) ^ hash ^ val;
      q += 4;
      hash += hash >> 11;
    }
  } else {
    for (; len > 3; len -= 4) {
      unsigned int val;
      hash += ((q)[0] + ((q)[1] << 8));
      val = (((q + 2)[0] + ((q + 2)[1] << 8)) << 11);
      hash = (hash << 16) ^ hash ^ val;
      q += 4;
      hash += hash >> 11;
    }
  }
  switch (len) {
  case 3:
    hash += ((q)[0] + ((q)[1] << 8));
    hash ^= hash << 16;
    hash ^= q[2] << 18;
    hash += hash >> 11;
    break;
  case 2:
    hash += ((q)[0] + ((q)[1] << 8));
    hash ^= hash << 11;
    hash += hash >> 17;
    break;
  case 1:
    hash += q[0];
    hash ^= hash << 10;
    hash += hash >> 1;
    break;
  case 0:
    break;
  }
  hash ^= hash << 3;
  hash += hash >> 5;
  hash ^= hash << 4;
  hash += hash >> 17;
  hash ^= hash << 25;
  hash += hash >> 6;
  return hash;
}
```