user: 下面的汇编指令对应的C源代码是什么:

```asm
<cftexp2>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  sub    $0x48,%rsp
  mov    %rsi,0x20(%rsp)
  mov    %edx,0x30(%rsp)
  mov    %rcx,0x38(%rsp)
  mov    %edi,%r15d
  sar    %r15d
  mov    %edi,%r14d
  sar    $0x2,%r14d
  cmp    $0x203,%edi
  jle    L11
  movslq %r15d,%rax
  shl    $0x3,%rax
  mov    %rax,0x18(%rsp)
  jmp    L101
L69:
  mov    %r14d,%edx
  sar    %edx
  mov    0x30(%rsp),%ecx
  mov    %ecx,%eax
  sub    %edx,%eax
  cltq
  mov    0x38(%rsp),%rdi
  lea    (%rdi,%rax,8),%r13
  mov    %ecx,%eax
  sub    %r14d,%eax
  cltq
  lea    (%rdi,%rax,8),%r12
  mov    %r14d,0x10(%rsp)
L147:
  mov    0x10(%rsp),%eax
  mov    %eax,%ebp
  sub    %r14d,%ebp
  cmp    %ebp,%r15d
  jle    L91
  add    %eax,%eax
  mov    %eax,0x4(%rsp)
  cltq
  shl    $0x3,%rax
  mov    %rax,0x8(%rsp)
  movslq %ebp,%rax
  mov    0x20(%rsp),%rcx
  lea    (%rcx,%rax,8),%rbx
  mov    %r12,0x28(%rsp)
  mov    0x18(%rsp),%r12
L13:
  mov    %r13,%rdx
  mov    %rbx,%rsi
  mov    %r14d,%edi
  call   <cftmdl1@plt>
  lea    (%rbx,%r12,1),%rsi
  mov    %r13,%rdx
  mov    %r14d,%edi
  call   <cftmdl1@plt>
  add    0x4(%rsp),%ebp
  add    0x8(%rsp),%rbx
  cmp    %ebp,%r15d
  jg     L13
  mov    0x28(%rsp),%r12
L91:
  mov    0x10(%rsp),%eax
  lea    (%rax,%rax,1),%ebp
  sub    %r14d,%ebp
  cmp    %ebp,%r15d
  jle    L102
  shl    $0x2,%eax
  mov    %eax,0x4(%rsp)
  cltq
  shl    $0x3,%rax
  mov    %rax,0x8(%rsp)
  movslq %ebp,%rax
  mov    0x20(%rsp),%rcx
  lea    (%rcx,%rax,8),%rbx
  mov    %r13,0x28(%rsp)
  mov    0x18(%rsp),%r13
L90:
  mov    %r12,%rdx
  mov    %rbx,%rsi
  mov    %r14d,%edi
  call   <cftmdl2@plt>
  lea    (%rbx,%r13,1),%rsi
  mov    %r12,%rdx
  mov    %r14d,%edi
  call   <cftmdl2@plt>
  add    0x4(%rsp),%ebp
  add    0x8(%rsp),%rbx
  cmp    %ebp,%r15d
  jg     L90
  mov    0x28(%rsp),%r13
L102:
  shll   $0x2,0x10(%rsp)
  mov    0x10(%rsp),%eax
  cmp    %eax,%r15d
  jg     L147
L45:
  sar    $0x2,%r14d
  cmp    $0x80,%r14d
  jle    L11
L101:
  cmp    %r14d,%r15d
  jg     L69
  jmp    L45
L11:
  cmp    %r14d,%r15d
  jle    L46
  mov    %r14d,%edx
  sar    %edx
  mov    0x30(%rsp),%ebp
  mov    %ebp,%eax
  sub    %edx,%eax
  cltq
  mov    0x38(%rsp),%r12
  lea    (%r12,%rax,8),%rax
  mov    %rax,0x8(%rsp)
  mov    %ebp,%eax
  sub    %r14d,%eax
  cltq
  lea    (%r12,%rax,8),%r13
  movslq %r15d,%rax
  shl    $0x3,%rax
  mov    %rax,0x10(%rsp)
  mov    %r14d,0x38(%rsp)
  mov    %r13,0x18(%rsp)
  mov    %r15d,0x4(%rsp)
L28:
  mov    0x38(%rsp),%eax
  mov    %eax,%r13d
  sub    %r14d,%r13d
  cmp    %r13d,0x4(%rsp)
  jle    L93
  add    %eax,%eax
  mov    %eax,0x28(%rsp)
  cltq
  shl    $0x3,%rax
  mov    %rax,0x30(%rsp)
  movslq %r13d,%rax
  mov    0x20(%rsp),%rcx
  lea    (%rcx,%rax,8),%rbx
L116:
  mov    0x8(%rsp),%rdx
  mov    %rbx,%rsi
  mov    %r14d,%edi
  call   <cftmdl1@plt>
  mov    %r12,%rcx
  mov    %ebp,%edx
  mov    %rbx,%rsi
  mov    %r14d,%edi
  call   <cftfx41@plt>
  mov    0x10(%rsp),%rax
  lea    (%rbx,%rax,1),%r15
  mov    0x8(%rsp),%rdx
  mov    %r15,%rsi
  mov    %r14d,%edi
  call   <cftmdl1@plt>
  mov    %r12,%rcx
  mov    %ebp,%edx
  mov    %r15,%rsi
  mov    %r14d,%edi
  call   <cftfx41@plt>
  add    0x28(%rsp),%r13d
  add    0x30(%rsp),%rbx
  cmp    %r13d,0x4(%rsp)
  jg     L116
L93:
  mov    0x38(%rsp),%eax
  lea    (%rax,%rax,1),%r13d
  sub    %r14d,%r13d
  cmp    %r13d,0x4(%rsp)
  jle    L29
  shl    $0x2,%eax
  mov    %eax,0x28(%rsp)
  cltq
  shl    $0x3,%rax
  mov    %rax,0x30(%rsp)
  movslq %r13d,%rax
  mov    0x20(%rsp),%rcx
  lea    (%rcx,%rax,8),%rbx
L86:
  mov    0x18(%rsp),%rdx
  mov    %rbx,%rsi
  mov    %r14d,%edi
  call   <cftmdl2@plt>
  mov    %r12,%rcx
  mov    %ebp,%edx
  mov    %rbx,%rsi
  mov    %r14d,%edi
  call   <cftfx42@plt>
  mov    0x10(%rsp),%rax
  lea    (%rbx,%rax,1),%r15
  mov    0x18(%rsp),%rdx
  mov    %r15,%rsi
  mov    %r14d,%edi
  call   <cftmdl2@plt>
  mov    %r12,%rcx
  mov    %ebp,%edx
  mov    %r15,%rsi
  mov    %r14d,%edi
  call   <cftfx42@plt>
  add    0x28(%rsp),%r13d
  add    0x30(%rsp),%rbx
  cmp    %r13d,0x4(%rsp)
  jg     L86
L29:
  shll   $0x2,0x38(%rsp)
  mov    0x38(%rsp),%eax
  cmp    %eax,0x4(%rsp)
  jg     L28
L46:
  add    $0x48,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
```

assistant: ```c
void cftexp2(int n, double *a, int nw, double *w) {
  void cftmdl1(int n, double *a, double *w);
  void cftmdl2(int n, double *a, double *w);
  void cftfx41(int n, double *a, int nw, double *w);
  void cftfx42(int n, double *a, int nw, double *w);
  int j, k, l, m;
  m = n >> 1;
  l = n >> 2;
  while (l > 128) {
    for (k = l; k < m; k <<= 2) {
      for (j = k - l; j < m; j += 2 * k) {
        cftmdl1(l, &a[j], &w[nw - (l >> 1)]);
        cftmdl1(l, &a[m + j], &w[nw - (l >> 1)]);
      }
      for (j = 2 * k - l; j < m; j += 4 * k) {
        cftmdl2(l, &a[j], &w[nw - l]);
        cftmdl2(l, &a[m + j], &w[nw - l]);
      }
    }
    l >>= 2;
  }
  for (k = l; k < m; k <<= 2) {
    for (j = k - l; j < m; j += 2 * k) {
      cftmdl1(l, &a[j], &w[nw - (l >> 1)]);
      cftfx41(l, &a[j], nw, w);
      cftmdl1(l, &a[m + j], &w[nw - (l >> 1)]);
      cftfx41(l, &a[m + j], nw, w);
    }
    for (j = 2 * k - l; j < m; j += 4 * k) {
      cftmdl2(l, &a[j], &w[nw - l]);
      cftfx42(l, &a[j], nw, w);
      cftmdl2(l, &a[m + j], &w[nw - l]);
      cftfx42(l, &a[m + j], nw, w);
    }
  }
}
```