user: 请将这段汇编代码片段转换成等效的C代码：

```asm
<malloc_i_cat>:
  endbr64
  push   %r15
  mov    %rcx,%r15
  push   %r14
  mov    %edx,%r14d
  push   %r13
  mov    %rsi,%r13
  push   %r12
  push   %rbp
  mov    %rdi,%rbp
  push   %rbx
  sub    $0x18,%rsp
  test   %rdi,%rdi
  je     L262
  cmpb   $0x0,(%rdi)
  je     L136
  lea    0x1(%rdi),%rcx
  xor    %ebx,%ebx
  mov    %rcx,%rax
  nopl   0x0(%rax)
L135:
  add    $0x1,%rax
  mov    %ebx,%edx
  add    $0x1,%ebx
  cmpb   $0x0,-0x1(%rax)
  jne    L135
  lea    0x1(%rbx,%r14,1),%edi
  mov    %rcx,0x8(%rsp)
  mov    %edx,0x4(%rsp)
  call   <malloc@plt>
  mov    %rax,%r12
  test   %rax,%rax
  je     L174
  mov    0x8(%rsp),%rcx
  mov    0x4(%rsp),%edx
  sub    %rcx,%rax
  cmp    $0xe,%rax
  jbe    L97
  cmp    $0x6,%edx
  jbe    L97
  lea    0x1(%rdx),%esi
  cmp    $0xe,%edx
  jbe    L143
  mov    %esi,%ecx
  xor    %eax,%eax
  shr    $0x4,%ecx
  shl    $0x4,%rcx
  nopl   0x0(%rax)
L19:
  movdqu 0x0(%rbp,%rax,1),%xmm0
  movups %xmm0,(%r12,%rax,1)
  add    $0x10,%rax
  cmp    %rcx,%rax
  jne    L19
  mov    %esi,%ecx
  and    $0xfffffff0,%ecx
  mov    %ecx,%eax
  cmp    %esi,%ecx
  je     L183
  mov    %edx,%edi
  sub    %ecx,%edi
  lea    0x1(%rdi),%esi
  cmp    $0x6,%edi
  jbe    L79
L61:
  mov    0x0(%rbp,%rcx,1),%rdi
  mov    %rdi,(%r12,%rcx,1)
  mov    %esi,%ecx
  and    $0xfffffff8,%ecx
  add    %ecx,%eax
  cmp    %esi,%ecx
  je     L183
L79:
  movslq %eax,%rcx
  movzbl 0x0(%rbp,%rcx,1),%esi
  mov    %sil,(%r12,%rcx,1)
  lea    0x1(%rax),%ecx
  cmp    %eax,%edx
  jle    L183
  movslq %ecx,%rsi
  movzbl 0x0(%rbp,%rsi,1),%edi
  mov    %dil,(%r12,%rsi,1)
  lea    0x2(%rax),%esi
  cmp    %ecx,%edx
  jle    L183
  movslq %esi,%rcx
  movzbl 0x0(%rbp,%rcx,1),%edi
  mov    %dil,(%r12,%rcx,1)
  lea    0x3(%rax),%ecx
  cmp    %esi,%edx
  jle    L183
  movslq %ecx,%rsi
  movzbl 0x0(%rbp,%rsi,1),%edi
  mov    %dil,(%r12,%rsi,1)
  lea    0x4(%rax),%esi
  cmp    %ecx,%edx
  jle    L183
  movslq %esi,%rcx
  movzbl 0x0(%rbp,%rcx,1),%edi
  mov    %dil,(%r12,%rcx,1)
  lea    0x5(%rax),%ecx
  cmp    %esi,%edx
  jle    L183
  movslq %ecx,%rsi
  add    $0x6,%eax
  movzbl 0x0(%rbp,%rsi,1),%edi
  mov    %dil,(%r12,%rsi,1)
  cmp    %ecx,%edx
  jle    L183
  cltq
  movzbl 0x0(%rbp,%rax,1),%edx
  mov    %dl,(%r12,%rax,1)
L183:
  movslq %ebx,%rcx
  add    %r12,%rcx
L69:
  test   %r14d,%r14d
  jle    L106
L222:
  movslq %ebx,%rcx
  movslq %r14d,%rsi
  xor    %eax,%eax
  add    %r12,%rcx
  nopw   0x0(%rax,%rax,1)
L240:
  mov    (%r15),%edx
  add    %eax,%edx
  movslq %edx,%rdx
  movzbl 0x0(%r13,%rdx,1),%edx
  mov    %dl,(%rcx,%rax,1)
  add    $0x1,%rax
  cmp    %rsi,%rax
  jne    L240
  add    %r14d,%ebx
  movslq %ebx,%rbx
  movb   $0x0,(%r12,%rbx,1)
  test   %rbp,%rbp
  je     L293
L173:
  mov    %rbp,%rdi
  call   <free@plt>
L293:
  add    (%r15),%r14d
  add    $0x1,%r14d
  mov    %r14d,(%r15)
L165:
  add    $0x18,%rsp
  mov    %r12,%rax
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
  cs nopw 0x0(%rax,%rax,1)
L262:
  lea    0x1(%rdx),%edi
  call   <malloc@plt>
  mov    %rax,%r12
  test   %rax,%rax
  je     L174
  xor    %ebx,%ebx
  test   %r14d,%r14d
  jg     L222
  movb   $0x0,(%r12)
  jmp    L293
  xchg   %ax,%ax
L97:
  add    $0x1,%edx
  xor    %eax,%eax
  movslq %edx,%rcx
  nopl   0x0(%rax,%rax,1)
L25:
  movzbl 0x0(%rbp,%rax,1),%edx
  mov    %dl,(%r12,%rax,1)
  add    $0x1,%rax
  cmp    %rax,%rcx
  jne    L25
  jmp    L183
  nopw   0x0(%rax,%rax,1)
L106:
  movb   $0x0,(%rcx)
  jmp    L173
L174:
  xor    %r12d,%r12d
  jmp    L165
L136:
  lea    0x1(%rdx),%edi
  call   <malloc@plt>
  mov    %rax,%r12
  test   %rax,%rax
  je     L174
  mov    %rax,%rcx
  xor    %ebx,%ebx
  jmp    L69
L143:
  xor    %eax,%eax
  xor    %ecx,%ecx
  jmp    L61
```

assistant: ```c
char *malloc_i_cat(char *dest, char src[(30) + 1], int count, int *pos) {
  char *buffer;
  int k;
  int i;
  int j;
  k = 0;
  i = -1;
  j = -1;
  if (dest != NULL)
    while (dest[k] != 0)
      k++;
  if ((buffer = malloc(k + count + 1)) == NULL)
    return (NULL);
  while ((i = i + 1) < k)
    buffer[i] = dest[i];
  while ((j = j + 1) < count)
    buffer[i + j] = src[*pos + j];
  buffer[i + j] = 0;
  if (dest != NULL)
    free(dest);
  *pos = *pos + count + 1;
  return (buffer);
}
```