user: What would the C source look like for the assembly code provided here?

```asm
<multiply>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  sub    $0x30,%rsp
  mov    %rdi,-0x28(%rbp)
  mov    %rsi,-0x30(%rbp)
  mov    -0x28(%rbp),%rax
  movzbl (%rax),%eax
  test   %al,%al
  jne    L91
  mov    -0x28(%rbp),%rax
  jmp    L14
L91:
  mov    -0x30(%rbp),%rax
  movzbl (%rax),%eax
  test   %al,%al
  jne    L16
  mov    -0x30(%rbp),%rax
  jmp    L14
L16:
  mov    -0x28(%rbp),%rax
  mov    %rax,%rdi
  call   <strlen@plt>
  mov    %eax,-0x10(%rbp)
  mov    -0x30(%rbp),%rax
  mov    %rax,%rdi
  call   <strlen@plt>
  mov    %eax,-0xc(%rbp)
  mov    -0x10(%rbp),%edx
  mov    -0xc(%rbp),%eax
  add    %edx,%eax
  add    $0x1,%eax
  mov    %eax,%edi
  call   <malloc@plt>
  mov    %rax,-0x8(%rbp)
  mov    -0x10(%rbp),%edx
  mov    -0xc(%rbp),%eax
  add    %edx,%eax
  lea    0x1(%rax),%edx
  mov    -0x8(%rbp),%rax
  mov    $0x30,%esi
  mov    %rax,%rdi
  call   <memset@plt>
  mov    -0x10(%rbp),%edx
  mov    -0xc(%rbp),%eax
  add    %edx,%eax
  movslq %eax,%rdx
  mov    -0x8(%rbp),%rax
  add    %rdx,%rax
  movb   $0x0,(%rax)
  mov    -0xc(%rbp),%eax
  sub    $0x1,%eax
  mov    %eax,-0x1c(%rbp)
  jmp    L1
L38:
  movl   $0x0,-0x14(%rbp)
  mov    -0x10(%rbp),%eax
  sub    $0x1,%eax
  mov    %eax,-0x18(%rbp)
  jmp    L40
L15:
  mov    -0x1c(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x30(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  movsbl %al,%eax
  lea    -0x30(%rax),%edx
  mov    -0x18(%rbp),%eax
  movslq %eax,%rcx
  mov    -0x28(%rbp),%rax
  add    %rcx,%rax
  movzbl (%rax),%eax
  movsbl %al,%eax
  sub    $0x30,%eax
  imul   %eax,%edx
  mov    -0x1c(%rbp),%ecx
  mov    -0x18(%rbp),%eax
  add    %ecx,%eax
  cltq
  lea    0x1(%rax),%rcx
  mov    -0x8(%rbp),%rax
  add    %rcx,%rax
  movzbl (%rax),%eax
  movsbl %al,%eax
  sub    $0x30,%eax
  add    %edx,%eax
  add    %eax,-0x14(%rbp)
  mov    -0x14(%rbp),%edx
  movslq %edx,%rax
  imul   $0x66666667,%rax,%rax
  shr    $0x20,%rax
  sar    $0x2,%eax
  mov    %edx,%esi
  sar    $0x1f,%esi
  sub    %esi,%eax
  mov    %eax,%ecx
  mov    %ecx,%eax
  shl    $0x2,%eax
  add    %ecx,%eax
  add    %eax,%eax
  mov    %edx,%ecx
  sub    %eax,%ecx
  mov    %ecx,%eax
  lea    0x30(%rax),%ecx
  mov    -0x1c(%rbp),%edx
  mov    -0x18(%rbp),%eax
  add    %edx,%eax
  cltq
  lea    0x1(%rax),%rdx
  mov    -0x8(%rbp),%rax
  add    %rdx,%rax
  mov    %ecx,%edx
  mov    %dl,(%rax)
  mov    -0x14(%rbp),%eax
  movslq %eax,%rdx
  imul   $0x66666667,%rdx,%rdx
  shr    $0x20,%rdx
  sar    $0x2,%edx
  sar    $0x1f,%eax
  mov    %eax,%ecx
  mov    %edx,%eax
  sub    %ecx,%eax
  mov    %eax,-0x14(%rbp)
  subl   $0x1,-0x18(%rbp)
L40:
  cmpl   $0x0,-0x18(%rbp)
  jns    L15
  mov    -0x14(%rbp),%eax
  lea    0x30(%rax),%ecx
  mov    -0x1c(%rbp),%edx
  mov    -0x18(%rbp),%eax
  add    %edx,%eax
  cltq
  lea    0x1(%rax),%rdx
  mov    -0x8(%rbp),%rax
  add    %rdx,%rax
  mov    %ecx,%edx
  mov    %dl,(%rax)
  subl   $0x1,-0x1c(%rbp)
L1:
  cmpl   $0x0,-0x1c(%rbp)
  jns    L38
  jmp    L99
L31:
  addq   $0x1,-0x8(%rbp)
L99:
  mov    -0x8(%rbp),%rax
  movzbl (%rax),%eax
  cmp    $0x30,%al
  jne    L46
  mov    -0x8(%rbp),%rax
  add    $0x1,%rax
  movzbl (%rax),%eax
  test   %al,%al
  jne    L31
L46:
  mov    -0x8(%rbp),%rax
L14:
  leave
  ret
```

assistant: ```c
char *multiply(char *num1, char *num2) {
  if (*num1 == '\0') {
    return num1;
  }
  if (*num2 == '\0') {
    return num2;
  }
  int i, j;
  int len1 = strlen(num1);
  int len2 = strlen(num2);
  char *result = malloc(len1 + len2 + 1);
  memset(result, '0', len1 + len2 + 1);
  result[len1 + len2] = '\0';
  for (i = len2 - 1; i >= 0; i--) {
    int carry = 0;
    for (j = len1 - 1; j >= 0; j--) {
      carry += (num2[i] - '0') * (num1[j] - '0') + (result[i + j + 1] - '0');
      result[i + j + 1] = carry % 10 + '0';
      carry /= 10;
    }
    result[i + j + 1] = carry + '0';
  }
  while (result[0] == '0' && result[1] != '\0') {
    result++;
  }
  return result;
}
```