user: 下面的汇编指令对应的C源代码是什么:

```asm
<CAST_cbc_encrypt>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  sub    $0x68,%rsp
  mov    %rdi,%rbp
  mov    %rsi,0x18(%rsp)
  mov    %rdx,0x20(%rsp)
  mov    %rcx,%r13
  mov    %r8,%r15
  mov    %fs:0x28,%rax
  mov    %rax,0x58(%rsp)
  xor    %eax,%eax
  test   %r9d,%r9d
  je     L197
  mov    %rdx,%rbx
  movzbl (%r8),%edx
  shl    $0x18,%rdx
  movzbl 0x1(%r8),%eax
  shl    $0x10,%rax
  or     %rdx,%rax
  movzbl 0x3(%r8),%edx
  or     %rdx,%rax
  movzbl 0x2(%r8),%edx
  shl    $0x8,%rdx
  or     %rax,%rdx
  movzbl 0x4(%r8),%eax
  shl    $0x18,%rax
  movzbl 0x5(%r8),%ecx
  shl    $0x10,%rcx
  or     %rax,%rcx
  movzbl 0x7(%r8),%eax
  or     %rax,%rcx
  movzbl 0x6(%r8),%eax
  shl    $0x8,%rax
  or     %rcx,%rax
  mov    %rbx,%rcx
  sub    $0x8,%rcx
  js     L187
  shr    $0x3,%rcx
  mov    %rcx,(%rsp)
  lea    0x8(,%rcx,8),%rbx
  mov    %rbx,0x8(%rsp)
  lea    (%rdi,%rbx,1),%r14
  mov    %rsi,%r12
  lea    0x40(%rsp),%rbx
  mov    %rax,%rsi
L46:
  movzbl 0x0(%rbp),%eax
  shl    $0x18,%rax
  movzbl 0x1(%rbp),%ecx
  shl    $0x10,%rcx
  or     %rax,%rcx
  movzbl 0x3(%rbp),%eax
  or     %rax,%rcx
  movzbl 0x2(%rbp),%eax
  shl    $0x8,%rax
  or     %rax,%rcx
  movzbl 0x4(%rbp),%eax
  shl    $0x18,%rax
  movzbl 0x5(%rbp),%edi
  shl    $0x10,%rdi
  or     %rdi,%rax
  movzbl 0x6(%rbp),%edi
  shl    $0x8,%rdi
  add    $0x8,%rbp
  or     %rdi,%rax
  movzbl -0x1(%rbp),%edi
  or     %rdi,%rax
  xor    %rcx,%rdx
  mov    %rdx,0x40(%rsp)
  xor    %rsi,%rax
  mov    %rax,0x48(%rsp)
  mov    %r13,%rsi
  mov    %rbx,%rdi
  call   <CAST_encrypt@plt>
  mov    0x40(%rsp),%rdx
  mov    0x48(%rsp),%rsi
  mov    %rdx,%rax
  shr    $0x18,%rax
  mov    %al,(%r12)
  mov    %rdx,%rax
  shr    $0x10,%rax
  mov    %al,0x1(%r12)
  movzbl %dh,%eax
  mov    %al,0x2(%r12)
  mov    %dl,0x3(%r12)
  mov    %rsi,%rax
  shr    $0x18,%rax
  mov    %al,0x4(%r12)
  mov    %rsi,%rax
  shr    $0x10,%rax
  mov    %al,0x5(%r12)
  mov    %rsi,%rax
  movzbl %ah,%eax
  mov    %al,0x6(%r12)
  add    $0x8,%r12
  mov    %sil,-0x1(%r12)
  cmp    %rbp,%r14
  jne    L46
  mov    %rsi,%rax
  mov    0x8(%rsp),%rsi
  add    %rsi,0x18(%rsp)
  mov    (%rsp),%rbx
  neg    %rbx
  mov    0x20(%rsp),%rsi
  lea    -0x10(%rsi,%rbx,8),%rcx
L187:
  cmp    $0xfffffffffffffff8,%rcx
  je     L206
  add    $0x8,%rcx
  add    %rcx,%rbp
  cmp    $0x8,%rcx
  ja     L200
  lea    D16(%rip),%rsi
  movslq (%rsi,%rcx,4),%rcx
  add    %rsi,%rcx
  notrack jmp *%rcx
  movzbl -0x1(%rbp),%ecx
  lea    -0x1(%rbp),%rbp
  jmp    L174
  mov    $0x0,%ecx
L174:
  movzbl -0x1(%rbp),%esi
  shl    $0x8,%rsi
  or     %rcx,%rsi
  lea    -0x1(%rbp),%rbp
L98:
  lea    -0x1(%rbp),%rdi
  movzbl -0x1(%rbp),%ecx
  shl    $0x10,%rcx
  or     %rsi,%rcx
L198:
  lea    -0x1(%rdi),%rbp
  movzbl -0x1(%rdi),%esi
  shl    $0x18,%rsi
  or     %rcx,%rsi
L29:
  lea    -0x1(%rbp),%rcx
  movzbl -0x1(%rbp),%edi
L157:
  lea    -0x1(%rcx),%rbp
  movzbl -0x1(%rcx),%ecx
  shl    $0x8,%rcx
  or     %rdi,%rcx
L66:
  lea    -0x1(%rbp),%r8
  movzbl -0x1(%rbp),%edi
  shl    $0x10,%rdi
  or     %rcx,%rdi
L30:
  movzbl -0x1(%r8),%ecx
  shl    $0x18,%rcx
  or     %rdi,%rcx
L39:
  xor    %rcx,%rdx
  mov    %rdx,0x40(%rsp)
  xor    %rax,%rsi
  mov    %rsi,0x48(%rsp)
  lea    0x40(%rsp),%rdi
  mov    %r13,%rsi
  call   <CAST_encrypt@plt>
  mov    0x40(%rsp),%rdx
  mov    0x48(%rsp),%rax
  mov    %rdx,%rcx
  shr    $0x18,%rcx
  mov    0x18(%rsp),%rsi
  mov    %cl,(%rsi)
  mov    %rdx,%rcx
  shr    $0x10,%rcx
  mov    %cl,0x1(%rsi)
  movzbl %dh,%ebx
  mov    %bl,0x2(%rsi)
  mov    %dl,0x3(%rsi)
  mov    %rax,%rcx
  shr    $0x18,%rcx
  mov    %cl,0x4(%rsi)
  mov    %rax,%rcx
  shr    $0x10,%rcx
  mov    %cl,0x5(%rsi)
  movzbl %ah,%ebx
  mov    %bl,0x6(%rsi)
  mov    %al,0x7(%rsi)
L206:
  mov    %rdx,%r8
  shr    $0x18,%r8
  mov    %rdx,%rdi
  shr    $0x10,%rdi
  movzbl %dh,%ebp
  mov    %rax,%rsi
  shr    $0x18,%rsi
  mov    %rax,%rcx
  shr    $0x10,%rcx
  movzbl %ah,%ebx
  mov    %rbx,%r9
  mov    %eax,%ebx
L190:
  mov    %r8b,(%r15)
  mov    %dil,0x1(%r15)
  mov    %bpl,0x2(%r15)
  mov    %dl,0x3(%r15)
  mov    %sil,0x4(%r15)
  mov    %cl,0x5(%r15)
  mov    %r9b,0x6(%r15)
  mov    %bl,0x7(%r15)
  mov    0x58(%rsp),%rax
  sub    %fs:0x28,%rax
  jne    L166
  add    $0x68,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
  mov    $0x0,%esi
  jmp    L98
  mov    %rbp,%rdi
  mov    $0x0,%ecx
  jmp    L198
  mov    $0x0,%esi
  jmp    L29
  mov    %rbp,%rcx
  mov    $0x0,%esi
  mov    $0x0,%edi
  jmp    L157
  mov    $0x0,%esi
  mov    $0x0,%ecx
  jmp    L66
  mov    %rbp,%r8
  mov    $0x0,%esi
  mov    $0x0,%edi
  jmp    L30
L200:
  mov    $0x0,%esi
  mov    $0x0,%ecx
  jmp    L39
L197:
  movzbl (%r8),%edx
  shl    $0x18,%rdx
  movzbl 0x1(%r8),%eax
  shl    $0x10,%rax
  or     %rdx,%rax
  movzbl 0x3(%r8),%edx
  or     %rdx,%rax
  movzbl 0x2(%r8),%edx
  shl    $0x8,%rdx
  or     %rax,%rdx
  mov    %rdx,%r14
  movzbl 0x4(%r8),%edx
  shl    $0x18,%rdx
  movzbl 0x5(%r8),%eax
  shl    $0x10,%rax
  or     %rdx,%rax
  movzbl 0x7(%r8),%edx
  or     %rdx,%rax
  movzbl 0x6(%r8),%ebx
  shl    $0x8,%rbx
  or     %rax,%rbx
  mov    0x20(%rsp),%rax
  mov    %rax,%r12
  sub    $0x8,%r12
  js     L92
  mov    %r12,%rax
  shr    $0x3,%rax
  mov    %rax,0x28(%rsp)
  lea    0x8(,%rax,8),%rax
  mov    %rax,0x30(%rsp)
  add    %rdi,%rax
  mov    %rax,0x8(%rsp)
  mov    0x18(%rsp),%r12
  lea    0x40(%rsp),%rax
  mov    %rax,0x10(%rsp)
  mov    %rcx,(%rsp)
  mov    %r8,0x38(%rsp)
L172:
  movzbl 0x0(%rbp),%edx
  shl    $0x18,%rdx
  movzbl 0x1(%rbp),%eax
  shl    $0x10,%rax
  or     %rdx,%rax
  movzbl 0x3(%rbp),%edx
  or     %rdx,%rax
  mov    %r14,%r15
  movzbl 0x2(%rbp),%r14d
  shl    $0x8,%r14
  or     %rax,%r14
  movzbl 0x4(%rbp),%edx
  shl    $0x18,%rdx
  movzbl 0x5(%rbp),%eax
  shl    $0x10,%rax
  or     %rax,%rdx
  movzbl 0x6(%rbp),%eax
  shl    $0x8,%rax
  add    $0x8,%rbp
  mov    %rbx,%r13
  movzbl -0x1(%rbp),%ebx
  or     %rdx,%rax
  or     %rax,%rbx
  mov    %r14,0x40(%rsp)
  mov    %rbx,0x48(%rsp)
  mov    (%rsp),%rsi
  mov    0x10(%rsp),%rdi
  call   <CAST_decrypt@plt>
  mov    %r15,%rdx
  xor    0x40(%rsp),%rdx
  mov    %r13,%rax
  xor    0x48(%rsp),%rax
  mov    %rdx,%rcx
  shr    $0x18,%rcx
  mov    %cl,(%r12)
  mov    %rdx,%rcx
  shr    $0x10,%rcx
  mov    %cl,0x1(%r12)
  movzbl %dh,%ecx
  mov    %cl,0x2(%r12)
  mov    %dl,0x3(%r12)
  mov    %rax,%rdx
  shr    $0x18,%rdx
  mov    %dl,0x4(%r12)
  mov    %rax,%rdx
  shr    $0x10,%rdx
  mov    %dl,0x5(%r12)
  movzbl %ah,%ecx
  mov    %cl,0x6(%r12)
  add    $0x8,%r12
  mov    %al,-0x1(%r12)
  cmp    %rbp,0x8(%rsp)
  jne    L172
  mov    (%rsp),%r13
  mov    0x38(%rsp),%r15
  mov    0x30(%rsp),%rsi
  add    %rsi,0x18(%rsp)
  mov    0x28(%rsp),%rax
  neg    %rax
  mov    0x20(%rsp),%rsi
  lea    -0x10(%rsi,%rax,8),%r12
L92:
  cmp    $0xfffffffffffffff8,%r12
  jne    L94
L90:
  mov    %r14,%r8
  shr    $0x18,%r8
  mov    %r14,%rdi
  shr    $0x10,%rdi
  mov    %r14,%rax
  movzbl %ah,%ebp
  mov    %r14d,%edx
  mov    %rbx,%rsi
  shr    $0x18,%rsi
  mov    %rbx,%rcx
  shr    $0x10,%rcx
  movzbl %bh,%eax
  mov    %rax,%r9
  jmp    L190
L94:
  movzbl 0x0(%rbp),%edx
  shl    $0x18,%rdx
  movzbl 0x1(%rbp),%eax
  shl    $0x10,%rax
  or     %rdx,%rax
  movzbl 0x3(%rbp),%edx
  or     %rdx,%rax
  movzbl 0x2(%rbp),%edx
  shl    $0x8,%rdx
  mov    %rdx,%rsi
  or     %rax,%rsi
  mov    %rsi,(%rsp)
  movzbl 0x4(%rbp),%edx
  shl    $0x18,%rdx
  movzbl 0x5(%rbp),%eax
  shl    $0x10,%rax
  or     %rdx,%rax
  movzbl 0x7(%rbp),%edx
  or     %rdx,%rax
  movzbl 0x6(%rbp),%edx
  shl    $0x8,%rdx
  or     %rax,%rdx
  mov    %rdx,%rbp
  mov    %rsi,0x40(%rsp)
  mov    %rdx,0x48(%rsp)
  lea    0x40(%rsp),%rdi
  mov    %r13,%rsi
  call   <CAST_decrypt@plt>
  mov    %r14,%rdx
  xor    0x40(%rsp),%rdx
  xor    0x48(%rsp),%rbx
  add    $0x8,%r12
  mov    0x18(%rsp),%rax
  add    %r12,%rax
  cmp    $0x8,%r12
  ja     L228
  lea    D3(%rip),%rsi
  movslq (%rsi,%r12,4),%rcx
  add    %rsi,%rcx
  notrack jmp *%rcx
  mov    %bl,-0x1(%rax)
  lea    -0x1(%rax),%rax
  movzbl %bh,%ecx
  mov    %cl,-0x1(%rax)
  lea    -0x1(%rax),%rax
  lea    -0x1(%rax),%rcx
  mov    %rbx,%rsi
  shr    $0x10,%rsi
  mov    %sil,-0x1(%rax)
L75:
  lea    -0x1(%rcx),%rax
  shr    $0x18,%rbx
  mov    %bl,-0x1(%rcx)
  lea    -0x1(%rax),%rcx
  mov    %dl,-0x1(%rax)
L201:
  lea    -0x1(%rcx),%rax
  movzbl %dh,%ebx
  mov    %bl,-0x1(%rcx)
  lea    -0x1(%rax),%rcx
  mov    %rdx,%rsi
  shr    $0x10,%rsi
  mov    %sil,-0x1(%rax)
L28:
  shr    $0x18,%rdx
  mov    %dl,-0x1(%rcx)
  mov    %rbp,%rbx
  mov    (%rsp),%r14
  jmp    L90
  mov    %rax,%rcx
  jmp    L75
  mov    %rax,%rcx
  jmp    L201
  mov    %rax,%rcx
  jmp    L28
L228:
  mov    %rbp,%rbx
  mov    (%rsp),%r14
  jmp    L90
L166:
  call   <__stack_chk_fail@plt>
```

assistant: ```c
void CAST_cbc_encrypt(const unsigned char *in, unsigned char *out, long length, const CAST_KEY *ks, unsigned char *iv, int enc) {
  register CAST_LONG tin0, tin1;
  register CAST_LONG tout0, tout1, xor0, xor1;
  register long l = length;
  CAST_LONG tin[2];
  if (enc) {
    (tout0 = ((unsigned long)(*((iv)++))) << 24L, tout0 |= ((unsigned long)(*((iv)++))) << 16L, tout0 |= ((unsigned long)(*((iv)++))) << 8L, tout0 |= ((unsigned long)(*((iv)++))));
    (tout1 = ((unsigned long)(*((iv)++))) << 24L, tout1 |= ((unsigned long)(*((iv)++))) << 16L, tout1 |= ((unsigned long)(*((iv)++))) << 8L, tout1 |= ((unsigned long)(*((iv)++))));
    iv -= 8;
    for (l -= 8; l >= 0; l -= 8) {
      (tin0 = ((unsigned long)(*((in)++))) << 24L, tin0 |= ((unsigned long)(*((in)++))) << 16L, tin0 |= ((unsigned long)(*((in)++))) << 8L, tin0 |= ((unsigned long)(*((in)++))));
      (tin1 = ((unsigned long)(*((in)++))) << 24L, tin1 |= ((unsigned long)(*((in)++))) << 16L, tin1 |= ((unsigned long)(*((in)++))) << 8L, tin1 |= ((unsigned long)(*((in)++))));
      tin0 ^= tout0;
      tin1 ^= tout1;
      tin[0] = tin0;
      tin[1] = tin1;
      CAST_encrypt(tin, ks);
      tout0 = tin[0];
      tout1 = tin[1];
      (*((out)++) = (unsigned char)(((tout0) >> 24L) & 0xff), *((out)++) = (unsigned char)(((tout0) >> 16L) & 0xff), *((out)++) = (unsigned char)(((tout0) >> 8L) & 0xff), *((out)++) = (unsigned char)(((tout0)) & 0xff));
      (*((out)++) = (unsigned char)(((tout1) >> 24L) & 0xff), *((out)++) = (unsigned char)(((tout1) >> 16L) & 0xff), *((out)++) = (unsigned char)(((tout1) >> 8L) & 0xff), *((out)++) = (unsigned char)(((tout1)) & 0xff));
    }
    if (l != -8) {
      {
        in += l + 8;
        tin0 = tin1 = 0;
        switch (l + 8) {
        case 8:
          tin1 = ((unsigned long)(*(--(in))));
        case 7:
          tin1 |= ((unsigned long)(*(--(in)))) << 8;
        case 6:
          tin1 |= ((unsigned long)(*(--(in)))) << 16;
        case 5:
          tin1 |= ((unsigned long)(*(--(in)))) << 24;
        case 4:
          tin0 = ((unsigned long)(*(--(in))));
        case 3:
          tin0 |= ((unsigned long)(*(--(in)))) << 8;
        case 2:
          tin0 |= ((unsigned long)(*(--(in)))) << 16;
        case 1:
          tin0 |= ((unsigned long)(*(--(in)))) << 24;
        }
      };
      tin0 ^= tout0;
      tin1 ^= tout1;
      tin[0] = tin0;
      tin[1] = tin1;
      CAST_encrypt(tin, ks);
      tout0 = tin[0];
      tout1 = tin[1];
      (*((out)++) = (unsigned char)(((tout0) >> 24L) & 0xff), *((out)++) = (unsigned char)(((tout0) >> 16L) & 0xff), *((out)++) = (unsigned char)(((tout0) >> 8L) & 0xff), *((out)++) = (unsigned char)(((tout0)) & 0xff));
      (*((out)++) = (unsigned char)(((tout1) >> 24L) & 0xff), *((out)++) = (unsigned char)(((tout1) >> 16L) & 0xff), *((out)++) = (unsigned char)(((tout1) >> 8L) & 0xff), *((out)++) = (unsigned char)(((tout1)) & 0xff));
    }
    (*((iv)++) = (unsigned char)(((tout0) >> 24L) & 0xff), *((iv)++) = (unsigned char)(((tout0) >> 16L) & 0xff), *((iv)++) = (unsigned char)(((tout0) >> 8L) & 0xff), *((iv)++) = (unsigned char)(((tout0)) & 0xff));
    (*((iv)++) = (unsigned char)(((tout1) >> 24L) & 0xff), *((iv)++) = (unsigned char)(((tout1) >> 16L) & 0xff), *((iv)++) = (unsigned char)(((tout1) >> 8L) & 0xff), *((iv)++) = (unsigned char)(((tout1)) & 0xff));
  } else {
    (xor0 = ((unsigned long)(*((iv)++))) << 24L, xor0 |= ((unsigned long)(*((iv)++))) << 16L, xor0 |= ((unsigned long)(*((iv)++))) << 8L, xor0 |= ((unsigned long)(*((iv)++))));
    (xor1 = ((unsigned long)(*((iv)++))) << 24L, xor1 |= ((unsigned long)(*((iv)++))) << 16L, xor1 |= ((unsigned long)(*((iv)++))) << 8L, xor1 |= ((unsigned long)(*((iv)++))));
    iv -= 8;
    for (l -= 8; l >= 0; l -= 8) {
      (tin0 = ((unsigned long)(*((in)++))) << 24L, tin0 |= ((unsigned long)(*((in)++))) << 16L, tin0 |= ((unsigned long)(*((in)++))) << 8L, tin0 |= ((unsigned long)(*((in)++))));
      (tin1 = ((unsigned long)(*((in)++))) << 24L, tin1 |= ((unsigned long)(*((in)++))) << 16L, tin1 |= ((unsigned long)(*((in)++))) << 8L, tin1 |= ((unsigned long)(*((in)++))));
      tin[0] = tin0;
      tin[1] = tin1;
      CAST_decrypt(tin, ks);
      tout0 = tin[0] ^ xor0;
      tout1 = tin[1] ^ xor1;
      (*((out)++) = (unsigned char)(((tout0) >> 24L) & 0xff), *((out)++) = (unsigned char)(((tout0) >> 16L) & 0xff), *((out)++) = (unsigned char)(((tout0) >> 8L) & 0xff), *((out)++) = (unsigned char)(((tout0)) & 0xff));
      (*((out)++) = (unsigned char)(((tout1) >> 24L) & 0xff), *((out)++) = (unsigned char)(((tout1) >> 16L) & 0xff), *((out)++) = (unsigned char)(((tout1) >> 8L) & 0xff), *((out)++) = (unsigned char)(((tout1)) & 0xff));
      xor0 = tin0;
      xor1 = tin1;
    }
    if (l != -8) {
      (tin0 = ((unsigned long)(*((in)++))) << 24L, tin0 |= ((unsigned long)(*((in)++))) << 16L, tin0 |= ((unsigned long)(*((in)++))) << 8L, tin0 |= ((unsigned long)(*((in)++))));
      (tin1 = ((unsigned long)(*((in)++))) << 24L, tin1 |= ((unsigned long)(*((in)++))) << 16L, tin1 |= ((unsigned long)(*((in)++))) << 8L, tin1 |= ((unsigned long)(*((in)++))));
      tin[0] = tin0;
      tin[1] = tin1;
      CAST_decrypt(tin, ks);
      tout0 = tin[0] ^ xor0;
      tout1 = tin[1] ^ xor1;
      {
        out += l + 8;
        switch (l + 8) {
        case 8:
          *(--(out)) = (unsigned char)(((tout1)) & 0xff);
        case 7:
          *(--(out)) = (unsigned char)(((tout1) >> 8) & 0xff);
        case 6:
          *(--(out)) = (unsigned char)(((tout1) >> 16) & 0xff);
        case 5:
          *(--(out)) = (unsigned char)(((tout1) >> 24) & 0xff);
        case 4:
          *(--(out)) = (unsigned char)(((tout0)) & 0xff);
        case 3:
          *(--(out)) = (unsigned char)(((tout0) >> 8) & 0xff);
        case 2:
          *(--(out)) = (unsigned char)(((tout0) >> 16) & 0xff);
        case 1:
          *(--(out)) = (unsigned char)(((tout0) >> 24) & 0xff);
        }
      };
      xor0 = tin0;
      xor1 = tin1;
    }
    (*((iv)++) = (unsigned char)(((xor0) >> 24L) & 0xff), *((iv)++) = (unsigned char)(((xor0) >> 16L) & 0xff), *((iv)++) = (unsigned char)(((xor0) >> 8L) & 0xff), *((iv)++) = (unsigned char)(((xor0)) & 0xff));
    (*((iv)++) = (unsigned char)(((xor1) >> 24L) & 0xff), *((iv)++) = (unsigned char)(((xor1) >> 16L) & 0xff), *((iv)++) = (unsigned char)(((xor1) >> 8L) & 0xff), *((iv)++) = (unsigned char)(((xor1)) & 0xff));
  }
  tin0 = tin1 = tout0 = tout1 = xor0 = xor1 = 0;
  tin[0] = tin[1] = 0;
}
```