user: Translate the below assembly code into C programming language:

```asm
<substring>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  sub    $0x28,%rsp
  test   %rdi,%rdi
  je     L167
  mov    %rdi,0x8(%rsp)
  mov    %esi,%r13d
  mov    %edx,%r15d
  xor    %r8d,%r8d
  cmp    %edx,%esi
  jge    L224
  mov    $0x1,%edi
  call   <malloc@plt>
  mov    0x8(%rsp),%r9
  mov    %rax,%r8
  cmpb   $0x0,(%r9)
  je     L99
  test   %r15d,%r15d
  jle    L103
  mov    %r9,%rbp
  mov    $0x1,%r14d
  xor    %r12d,%r12d
  xor    %ebx,%ebx
  jmp    L51
  nopw   0x0(%rax,%rax,1)
L94:
  cmp    %ebx,%r15d
  je     L55
L51:
  cmp    %ebx,%r13d
  jg     L136
  movslq %r12d,%rdx
  cmp    %r12d,%r14d
  je     L173
L115:
  movzbl 0x0(%rbp),%eax
  add    $0x1,%r12d
  mov    %al,(%r8,%rdx,1)
L136:
  add    $0x1,%rbp
  add    $0x1,%ebx
  cmpb   $0x0,0x0(%rbp)
  jne    L94
L66:
  cmp    %ebx,%r13d
  jg     L204
L224:
  add    $0x28,%rsp
  mov    %r8,%rax
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
  xchg   %ax,%ax
L55:
  movslq %r12d,%rbp
  lea    (%r8,%rbp,1),%rax
  cmp    %r14d,%r12d
  je     L108
L52:
  movb   $0x0,(%rax)
  jmp    L66
  nopl   (%rax)
L173:
  lea    (%r12,%r12,1),%r14d
  mov    %rdx,0x18(%rsp)
  mov    %r14d,%edi
  mov    %r9,0x10(%rsp)
  mov    %r8,0x8(%rsp)
  call   <malloc@plt>
  mov    0x8(%rsp),%r8
  mov    0x18(%rsp),%rdx
  mov    0x10(%rsp),%r9
  mov    %rax,%r10
  mov    %r8,%rsi
  lea    (%rax,%rdx,1),%rdi
  sub    %rax,%rsi
  test   %r12d,%r12d
  je     L212
  nopl   0x0(%rax,%rax,1)
L156:
  movzbl (%rsi,%rax,1),%ecx
  add    $0x1,%rax
  mov    %cl,-0x1(%rax)
  cmp    %rdi,%rax
  jne    L156
L220:
  mov    %r8,%rdi
  mov    %rdx,0x18(%rsp)
  mov    %r9,0x10(%rsp)
  mov    %r10,0x8(%rsp)
  call   <free@plt>
  mov    0x8(%rsp),%r8
  mov    0x10(%rsp),%r9
  mov    0x18(%rsp),%rdx
  jmp    L115
  nopl   0x0(%rax,%rax,1)
L108:
  lea    0x1(%r12),%edi
  mov    %r9,0x10(%rsp)
  mov    %r8,0x8(%rsp)
  call   <malloc@plt>
  test   %r12d,%r12d
  mov    0x8(%rsp),%r8
  mov    0x10(%rsp),%r9
  mov    %rax,%r14
  je     L96
  lea    -0x1(%r12),%eax
  mov    %r8,%rcx
  lea    0x1(%r14,%rax,1),%rsi
  sub    %r14,%rcx
  mov    %r14,%rax
  nopl   0x0(%rax)
L127:
  movzbl (%rcx,%rax,1),%edx
  add    $0x1,%rax
  mov    %dl,-0x1(%rax)
  cmp    %rsi,%rax
  jne    L127
L96:
  mov    %r8,%rdi
  mov    %r9,0x8(%rsp)
  call   <free@plt>
  mov    0x8(%rsp),%r9
  lea    (%r14,%rbp,1),%rax
  mov    %r14,%r8
  jmp    L52
  xchg   %ax,%ax
L204:
  lea    0x1(%rbx),%edx
  mov    %r13d,%ecx
  lea    D0(%rip),%rdi
  mov    %r9,%rsi
  call   <printf@plt>
  xor    %r8d,%r8d
  jmp    L224
L167:
  lea    D18(%rip),%rdi
  call   <puts@plt>
  xor    %r8d,%r8d
  jmp    L224
L99:
  xor    %ebx,%ebx
  jmp    L66
L103:
  xor    %ebx,%ebx
  jmp    L52
L212:
  xor    %edx,%edx
  jmp    L220
```

tool_calls: name: retrieve_data
arguments: tag: D0
type: string
name: retrieve_data
arguments: tag: D18
type: string

tool: D0: %s has a length of %d but was given a start index of %d


tool: D18: substring() was given a null message!

assistant: ```c
char *substring(char *message, int start, int end) {
  if (message == NULL) {
    puts("substring() was given a null message!");
    return NULL;
  }
  if (start == end || start > end) {
    return NULL;
  }
  int messIndex = 0, strIndex = 0, size = 1;
  char *string = (char *)malloc(sizeof(char));
  while (message[messIndex] != 0) {
    if (messIndex >= end) {
      if (strIndex == size) {
        char *tmpString = (char *)malloc(sizeof(char) * (size) + 1);
        for (int i = 0; i < size; i++) {
          tmpString[i] = string[i];
        }
        size = size + 1;
        free(string);
        string = tmpString;
      }
      string[strIndex] = 0;
      break;
    } else if (messIndex >= start) {
      if (strIndex == size) {
        char *tmpString = (char *)malloc(sizeof(char) * (size * 2));
        for (int i = 0; i < size; i++) {
          tmpString[i] = string[i];
        }
        size = size * 2;
        free(string);
        string = tmpString;
      }
      string[strIndex] = message[messIndex];
      strIndex++;
    }
    messIndex++;
  }
  if (messIndex < start) {
    printf("%s has a length of %d but was given a start index of %d\n", message, messIndex + 1, start);
    return NULL;
  }
  return string;
}
```