user: What is the c source code of the assembly code below:

```asm
<mjt_pton6>:
  endbr64
  push   %r13
  mov    %rsi,%r13
  push   %r12
  xor    %r12d,%r12d
  push   %rbp
  push   %rbx
  sub    $0x28,%rsp
  movzbl (%rdi),%ecx
  mov    %fs:0x28,%rax
  mov    %rax,0x18(%rsp)
  xor    %eax,%eax
  mov    %rsp,%rbx
  cmp    $0x3a,%cl
  je     L162
L248:
  mov    %rbx,%rbp
  lea    0x10(%rsp),%r8
L241:
  mov    %rdi,%rsi
  xor    %eax,%eax
  jmp    L332
  nopw   0x0(%rax,%rax,1)
L145:
  movsbl %dl,%edx
L331:
  shl    $0x4,%eax
  or     %edx,%eax
  cmp    $0xffff,%eax
  ja     L102
L230:
  movzbl 0x1(%rsi),%ecx
  add    $0x1,%rsi
L332:
  lea    -0x30(%rcx),%edx
  cmp    $0x9,%dl
  jbe    L145
  lea    -0x61(%rcx),%edx
  cmp    $0x5,%dl
  ja     L103
  sub    $0x57,%ecx
  shl    $0x4,%eax
  movsbl %cl,%edx
  or     %edx,%eax
  cmp    $0xffff,%eax
  jbe    L230
L102:
  xor    %eax,%eax
L291:
  mov    0x18(%rsp),%rdx
  sub    %fs:0x28,%rdx
  jne    L276
  add    $0x28,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  ret
  nopw   0x0(%rax,%rax,1)
L103:
  lea    -0x41(%rcx),%edx
  cmp    $0x5,%dl
  ja     L43
  sub    $0x37,%ecx
  movsbl %cl,%edx
  jmp    L331
  nopl   0x0(%rax,%rax,1)
L162:
  cmpb   $0x3a,0x1(%rdi)
  jne    L102
  movzbl 0x2(%rdi),%ecx
  mov    %rbx,%r12
  add    $0x2,%rdi
  jmp    L248
  cs nopw 0x0(%rax,%rax,1)
L43:
  cmp    %rsi,%rdi
  je     L219
  cmp    $0x3a,%cl
  jne    L339
  mov    %r8,%rdx
  cmp    %r8,%rbp
  je     L102
  movzbl 0x1(%rsi),%ecx
  add    $0x2,%rbp
  lea    0x1(%rsi),%rdi
  mov    %ax,-0x2(%rbp)
  cmp    $0x3a,%cl
  jne    L241
  test   %r12,%r12
  jne    L102
  movzbl 0x2(%rsi),%ecx
  lea    0x2(%rsi),%rdi
  mov    %rbp,%r12
  test   %cl,%cl
  jne    L241
  jmp    L213
L339:
  test   %cl,%cl
  jne    L198
  lea    0x10(%rsp),%rdx
  cmp    %rdx,%rbp
  jae    L102
  mov    %ax,0x0(%rbp)
  add    $0x2,%rbp
L213:
  mov    %rdx,%rax
  sub    %rbp,%rax
  sar    %rax
  test   %eax,%eax
  mov    %eax,%edx
  setne  %cl
  test   %r12,%r12
  setne  %al
  cmp    %al,%cl
  jne    L102
  jmp    L287
L171:
  cmp    %rbx,%rbp
  jbe    L272
  movzwl (%rbx),%eax
  add    $0x2,%r13
  add    $0x2,%rbx
  rol    $0x8,%ax
  mov    %ax,-0x2(%r13)
L287:
  cmp    %rbx,%r12
  jne    L171
  test   %edx,%edx
  je     L197
  lea    0x0(%r13,%rdx,2),%rax
L148:
  movb   $0x0,0x0(%r13)
  add    $0x2,%r13
  movb   $0x0,-0x1(%r13)
  cmp    %rax,%r13
  jne    L148
L197:
  mov    $0xffffffff,%edx
  jmp    L171
L219:
  cmp    %r12,%rbp
  jne    L102
  test   %cl,%cl
  jne    L102
L91:
  lea    0x10(%rsp),%rdx
  jmp    L213
L198:
  cmp    $0x2e,%cl
  jne    L102
  lea    0xc(%rsp),%rax
  cmp    %rax,%rbp
  ja     L102
  mov    %r13,%rsi
  call   <mjt_pton4@plt>
  test   %eax,%eax
  je     L102
  movzwl 0x0(%r13),%eax
  add    $0x4,%rbp
  rol    $0x8,%ax
  mov    %ax,-0x4(%rbp)
  movzwl 0x2(%r13),%eax
  rol    $0x8,%ax
  mov    %ax,-0x2(%rbp)
  jmp    L91
L272:
  mov    $0x1,%eax
  jmp    L291
L276:
  call   <__stack_chk_fail@plt>
```

assistant: ```c
int mjt_pton6(const char *c, void *dst) {
  unsigned short w[8], *a = w, *z, *i;
  unsigned v, o;
  const char *sc;
  unsigned char *d = (unsigned char *)dst;
  if (*c != ':')
    z = (unsigned short *)0;
  else if (*++c != ':')
    return 0;
  else
    ++c, z = a;
  i = 0;
  for (;;) {
    v = 0;
    sc = c;
    for (;;) {
      if (*c >= '0' && *c <= '9')
        o = *c - '0';
      else if (*c >= 'a' && *c <= 'f')
        o = *c - 'a' + 10;
      else if (*c >= 'A' && *c <= 'F')
        o = *c - 'A' + 10;
      else
        break;
      v = (v << 4) | o;
      if (v > 0xffff)
        return 0;
      ++c;
    }
    if (sc == c) {
      if (z == a && !*c)
        break;
      else
        return 0;
    }
    if (*c == ':') {
      if (a >= w + 8)
        return 0;
      *a++ = v;
      if (*++c == ':') {
        if (z)
          return 0;
        z = a;
        if (!*++c)
          break;
      }
    } else if (!*c) {
      if (a >= w + 8)
        return 0;
      *a++ = v;
      break;
    } else if (*c == '.') {
      if (a > w + 6)
        return 0;
      if (!mjt_pton4(sc, d))
        return 0;
      *a++ = ((unsigned)(d[0]) << 8) | d[1];
      *a++ = ((unsigned)(d[2]) << 8) | d[3];
      break;
    } else
      return 0;
  }
  v = w + 8 - a;
  if ((v && !z) || (!v && z))
    return 0;
  for (i = w;; ++i) {
    if (i == z)
      while (v--) {
        *d++ = '\0';
        *d++ = '\0';
      }
    if (i >= a)
      break;
    *d++ = (unsigned char)((*i >> 8) & 255);
    *d++ = (unsigned char)(*i & 255);
  }
  return 1;
}
```