user: 下面的汇编指令对应的C源代码是什么：

```asm
<lsx_ddct>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  sub    $0x18,%rsp
  mov    %edi,%ebx
  mov    %esi,0xc(%rsp)
  mov    %rdx,%rbp
  mov    %rcx,%r12
  mov    %r8,%r14
  mov    (%rcx),%r13d
  lea    0x0(,%r13,4),%eax
  cmp    %edi,%eax
  jl     L143
L137:
  mov    0x4(%r12),%r15d
  cmp    %r15d,%ebx
  jg     L65
L148:
  cmpl   $0x0,0xc(%rsp)
  js     L27
  movslq %r13d,%r13
  lea    (%r14,%r13,8),%r13
  mov    %r13,%rcx
  mov    %r15d,%edx
  mov    %rbp,%rsi
  mov    %ebx,%edi
  call   <dctsub@plt>
  cmp    $0x4,%ebx
  jg     L142
  je     L138
  movsd  0x0(%rbp),%xmm0
  movsd  0x8(%rbp),%xmm1
  movapd %xmm0,%xmm3
  subsd  %xmm1,%xmm3
  addsd  %xmm1,%xmm0
  movsd  %xmm0,0x0(%rbp)
  cmp    $0x2,%ebx
  jg     L99
  jmp    L150
L143:
  mov    %edi,%r13d
  sar    $0x2,%r13d
  mov    %r8,%rdx
  mov    %rcx,%rsi
  mov    %r13d,%edi
  call   <makewt@plt>
  jmp    L137
L65:
  movslq %r13d,%rax
  lea    (%r14,%rax,8),%rdx
  mov    %r12,%rsi
  mov    %ebx,%edi
  call   <makect@plt>
  mov    %ebx,%r15d
  jmp    L148
L27:
  movslq %ebx,%rax
  movsd  -0x8(%rbp,%rax,8),%xmm3
  lea    -0x2(%rbx),%eax
  cmp    $0x1,%eax
  jle    L43
  cltq
  lea    0x0(,%rax,8),%rdx
  lea    0x0(%rbp,%rdx,1),%rax
  lea    -0x10(%rbp,%rdx,1),%rdx
  lea    -0x4(%rbx),%ecx
  shr    %ecx
  mov    %ecx,%ecx
  shl    $0x4,%rcx
  sub    %rcx,%rdx
L125:
  movsd  (%rax),%xmm0
  movsd  -0x8(%rax),%xmm1
  movapd %xmm0,%xmm2
  subsd  %xmm1,%xmm2
  movsd  %xmm2,0x8(%rax)
  addsd  %xmm1,%xmm0
  movsd  %xmm0,(%rax)
  sub    $0x10,%rax
  cmp    %rdx,%rax
  jne    L125
L43:
  movsd  0x0(%rbp),%xmm0
  movapd %xmm0,%xmm1
  subsd  %xmm3,%xmm1
  movsd  %xmm1,0x8(%rbp)
  addsd  %xmm3,%xmm0
  movsd  %xmm0,0x0(%rbp)
  cmp    $0x4,%ebx
  jg     L76
  je     L174
L20:
  movslq %r13d,%r13
  lea    (%r14,%r13,8),%rcx
  mov    %r15d,%edx
  mov    %rbp,%rsi
  mov    %ebx,%edi
  call   <dctsub@plt>
  jmp    L79
L76:
  movslq %r13d,%rax
  lea    (%r14,%rax,8),%rcx
  mov    %r15d,%edx
  mov    %rbp,%rsi
  mov    %ebx,%edi
  call   <rftbsub@plt>
  lea    0x8(%r12),%rsi
  mov    %rbp,%rdx
  mov    %ebx,%edi
  call   <bitrv2@plt>
  mov    %r14,%rdx
  mov    %rbp,%rsi
  mov    %ebx,%edi
  call   <cftbsub@plt>
  jmp    L20
L174:
  mov    %r14,%rdx
  mov    %rbp,%rsi
  mov    $0x4,%edi
  call   <cftfsub@plt>
  jmp    L20
L142:
  lea    0x8(%r12),%rsi
  mov    %rbp,%rdx
  mov    %ebx,%edi
  call   <bitrv2@plt>
  mov    %r14,%rdx
  mov    %rbp,%rsi
  mov    %ebx,%edi
  call   <cftfsub@plt>
  mov    %r13,%rcx
  mov    %r15d,%edx
  mov    %rbp,%rsi
  mov    %ebx,%edi
  call   <rftfsub@plt>
L121:
  movsd  0x0(%rbp),%xmm0
  movsd  0x8(%rbp),%xmm1
  movapd %xmm0,%xmm3
  subsd  %xmm1,%xmm3
  addsd  %xmm1,%xmm0
  movsd  %xmm0,0x0(%rbp)
L99:
  lea    0x8(%rbp),%rax
  mov    $0x2,%edx
L16:
  movsd  0x8(%rax),%xmm0
  movsd  0x10(%rax),%xmm1
  movapd %xmm0,%xmm2
  subsd  %xmm1,%xmm2
  movsd  %xmm2,(%rax)
  addsd  %xmm1,%xmm0
  movsd  %xmm0,0x8(%rax)
  add    $0x2,%edx
  add    $0x10,%rax
  cmp    %edx,%ebx
  jg     L16
L150:
  movslq %ebx,%rbx
  movsd  %xmm3,-0x8(%rbp,%rbx,8)
L79:
  add    $0x18,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
L138:
  mov    %r14,%rdx
  mov    %rbp,%rsi
  mov    $0x4,%edi
  call   <cftfsub@plt>
  jmp    L121
```

assistant: ```c
void lsx_ddct(int n, int isgn, double *a, int *ip, double *w) {
  int j, nw, nc;
  double xr;
  nw = ip[0];
  if (n > (nw << 2)) {
    nw = n >> 2;
    makewt(nw, ip, w);
  }
  nc = ip[1];
  if (n > nc) {
    nc = n;
    makect(nc, ip, w + nw);
  }
  if (isgn < 0) {
    xr = a[n - 1];
    for (j = n - 2; j >= 2; j -= 2) {
      a[j + 1] = a[j] - a[j - 1];
      a[j] += a[j - 1];
    }
    a[1] = a[0] - xr;
    a[0] += xr;
    if (n > 4) {
      rftbsub(n, a, nc, w + nw);
      bitrv2(n, ip + 2, a);
      cftbsub(n, a, w);
    } else if (n == 4) {
      cftfsub(n, a, w);
    }
  }
  dctsub(n, a, nc, w + nw);
  if (isgn >= 0) {
    if (n > 4) {
      bitrv2(n, ip + 2, a);
      cftfsub(n, a, w);
      rftfsub(n, a, nc, w + nw);
    } else if (n == 4) {
      cftfsub(n, a, w);
    }
    xr = a[0] - a[1];
    a[0] += a[1];
    for (j = 2; j < n; j += 2) {
      a[j - 1] = a[j] - a[j + 1];
      a[j] += a[j + 1];
    }
    a[n - 1] = xr;
  }
}
```