user: 请从给定的汇编指令推导出C源代码：

```asm
<mod_ssi_parse_ssi_stmt_offlen>:
  endbr64
  push   %r15
  lea    0x5(%rsi),%r15
  push   %r14
  push   %r13
  mov    %esi,%r13d
  push   %r12
  neg    %r13d
  mov    %rdi,%r12
  push   %rbp
  mov    %rsi,%rbp
  push   %rbx
  sub    $0x18,%rsp
  movl   $0x5,(%rdi)
  mov    %edx,0xc(%rsp)
  nopl   0x0(%rax)
L220:
  movsbl (%r15),%edi
  lea    0x0(%r13,%r15,1),%ebx
  mov    %r15,%r14
  add    $0x1,%r15
  call   <light_isalpha@plt>
  test   %rax,%rax
  jne    L220
  mov    %ebx,%eax
  sub    (%r12),%eax
  mov    %eax,0x4(%r12)
  je     L143
  lea    0x3(%rbx),%eax
  cmp    0xc(%rsp),%eax
  je     L139
  movsbl (%r14),%edi
  call   <isspace@plt>
  test   %rax,%rax
  je     L143
  movslq %ebx,%rax
  lea    0x1(%rbp,%rax,1),%r13
  nopw   0x0(%rax,%rax,1)
L169:
  movsbl 0x0(%r13),%edi
  mov    %ebx,%r14d
  add    $0x1,%r13
  add    $0x1,%ebx
  call   <isspace@plt>
  test   %rax,%rax
  jne    L169
  add    $0x4,%r14d
  cmp    0xc(%rsp),%r14d
  je     L139
  movslq %ebx,%rdx
  mov    %ebx,0x8(%r12)
  lea    0x0(%rbp,%rdx,1),%r15
  sub    %r15d,%ebx
L170:
  movsbl (%r15),%edi
  lea    (%rbx,%r15,1),%r13d
  mov    %r15,%r14
  add    $0x1,%r15
  call   <light_isalpha@plt>
  test   %rax,%rax
  jne    L170
  mov    %r13d,%eax
  sub    0x8(%r12),%eax
  mov    %eax,0xc(%r12)
  je     L143
  add    $0x1,%r13d
  cmpb   $0x3d,(%r14)
  jne    L143
  mov    0xc(%rsp),%r14d
  mov    %r13d,0x10(%r12)
  movslq %r13d,%rdi
  add    %rbp,%rdi
  mov    %r14d,%esi
  sub    %r13d,%esi
  sub    $0x3,%esi
  call   <mod_ssi_parse_ssi_stmt_value@plt>
  mov    %eax,0x14(%r12)
  mov    %eax,%ebx
  test   %eax,%eax
  je     L143
  add    %r13d,%ebx
  lea    0x3(%rbx),%eax
  cmp    %r14d,%eax
  je     L172
  movslq %ebx,%r13
  movsbl 0x0(%rbp,%r13,1),%edi
  call   <isspace@plt>
  test   %rax,%rax
  je     L143
  lea    0x1(%rbp,%r13,1),%r13
  nopw   0x0(%rax,%rax,1)
L201:
  movsbl 0x0(%r13),%edi
  mov    %ebx,%r14d
  add    $0x1,%r13
  add    $0x1,%ebx
  call   <isspace@plt>
  test   %rax,%rax
  jne    L201
  add    $0x4,%r14d
  cmp    0xc(%rsp),%r14d
  je     L172
  movslq %ebx,%rdx
  mov    %ebx,0x18(%r12)
  lea    0x0(%rbp,%rdx,1),%r14
  sub    %r14d,%ebx
L13:
  movsbl (%r14),%edi
  lea    (%rbx,%r14,1),%r13d
  mov    %r14,%r15
  add    $0x1,%r14
  call   <light_isalpha@plt>
  test   %rax,%rax
  jne    L13
  mov    %r13d,%eax
  sub    0x18(%r12),%eax
  mov    %eax,0x1c(%r12)
  je     L143
  add    $0x1,%r13d
  cmpb   $0x3d,(%r15)
  jne    L143
  mov    0xc(%rsp),%ebx
  mov    %r13d,0x20(%r12)
  movslq %r13d,%rdi
  add    %rbp,%rdi
  mov    %ebx,%esi
  sub    %r13d,%esi
  sub    $0x3,%esi
  call   <mod_ssi_parse_ssi_stmt_value@plt>
  mov    %eax,0x24(%r12)
  test   %eax,%eax
  je     L143
  add    %r13d,%eax
  mov    $0xa,%r8d
  lea    0x3(%rax),%edx
  cmp    %ebx,%edx
  je     L176
  movslq %eax,%rbx
  movsbl 0x0(%rbp,%rbx,1),%edi
  call   <isspace@plt>
  test   %rax,%rax
  je     L143
  nopl   (%rax)
L235:
  movsbl 0x1(%rbp,%rbx,1),%edi
  mov    %ebx,%r12d
  add    $0x1,%rbx
  call   <isspace@plt>
  test   %rax,%rax
  jne    L235
  add    $0x4,%r12d
  cmp    0xc(%rsp),%r12d
  jne    L143
  mov    $0xa,%r8d
L176:
  add    $0x18,%rsp
  mov    %r8d,%eax
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
  nopl   0x0(%rax)
L172:
  mov    $0x6,%r8d
  jmp    L176
L139:
  mov    $0x2,%r8d
  jmp    L176
  nopl   0x0(%rax,%rax,1)
L143:
  mov    $0xffffffff,%r8d
  jmp    L176
```

assistant: ```c
int mod_ssi_parse_ssi_stmt_offlen(int o[10], const char *const s, const int len) {
  int n = 5;
  o[0] = n;
  for (; light_isalpha(s[n]); ++n)
    ;
  o[1] = n - o[0];
  if (0 == o[1])
    return -1;
  if (n + 3 == len)
    return 2;
  if (!isspace(s[n]))
    return -1;
  do {
    ++n;
  } while (isspace(s[n]));
  if (n + 3 == len)
    return 2;
  o[2] = n;
  for (; light_isalpha(s[n]); ++n)
    ;
  o[3] = n - o[2];
  if (0 == o[3] || s[n++] != '=')
    return -1;
  o[4] = n;
  o[5] = mod_ssi_parse_ssi_stmt_value(s + n, len - n - 3);
  if (0 == o[5])
    return -1;
  n += o[5];
  if (n + 3 == len)
    return 6;
  if (!isspace(s[n]))
    return -1;
  do {
    ++n;
  } while (isspace(s[n]));
  if (n + 3 == len)
    return 6;
  o[6] = n;
  for (; light_isalpha(s[n]); ++n)
    ;
  o[7] = n - o[6];
  if (0 == o[7] || s[n++] != '=')
    return -1;
  o[8] = n;
  o[9] = mod_ssi_parse_ssi_stmt_value(s + n, len - n - 3);
  if (0 == o[9])
    return -1;
  n += o[9];
  if (n + 3 == len)
    return 10;
  if (!isspace(s[n]))
    return -1;
  do {
    ++n;
  } while (isspace(s[n]));
  if (n + 3 == len)
    return 10;
  return -1;
}
```