user: Converte this assembly snippet into its equivalent C code:

```asm
<lsx_ddct_f>:
  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     L91
L43:
  mov    0x4(%r12),%r15d
  cmp    %r15d,%ebx
  jg     L161
L40:
  cmpl   $0x0,0xc(%rsp)
  js     L77
  movslq %r13d,%r13
  lea    (%r14,%r13,4),%r13
  mov    %r13,%rcx
  mov    %r15d,%edx
  mov    %rbp,%rsi
  mov    %ebx,%edi
  call   <dctsub@plt>
  cmp    $0x4,%ebx
  jg     L137
  je     L31
  movss  0x0(%rbp),%xmm0
  movss  0x4(%rbp),%xmm1
  movaps %xmm0,%xmm3
  subss  %xmm1,%xmm3
  addss  %xmm1,%xmm0
  movss  %xmm0,0x0(%rbp)
  cmp    $0x2,%ebx
  jg     L132
  jmp    L117
L91:
  mov    %edi,%r13d
  sar    $0x2,%r13d
  mov    %r8,%rdx
  mov    %rcx,%rsi
  mov    %r13d,%edi
  call   <makewt@plt>
  jmp    L43
L161:
  movslq %r13d,%rax
  lea    (%r14,%rax,4),%rdx
  mov    %r12,%rsi
  mov    %ebx,%edi
  call   <makect@plt>
  mov    %ebx,%r15d
  jmp    L40
L77:
  movslq %ebx,%rax
  movss  -0x4(%rbp,%rax,4),%xmm3
  lea    -0x2(%rbx),%eax
  cmp    $0x1,%eax
  jle    L89
  cltq
  lea    0x0(,%rax,4),%rdx
  lea    0x0(%rbp,%rdx,1),%rax
  lea    -0x8(%rbp,%rdx,1),%rdx
  lea    -0x4(%rbx),%ecx
  shr    %ecx
  mov    %ecx,%ecx
  shl    $0x3,%rcx
  sub    %rcx,%rdx
L173:
  movss  (%rax),%xmm0
  movss  -0x4(%rax),%xmm1
  movaps %xmm0,%xmm2
  subss  %xmm1,%xmm2
  movss  %xmm2,0x4(%rax)
  addss  %xmm1,%xmm0
  movss  %xmm0,(%rax)
  sub    $0x8,%rax
  cmp    %rdx,%rax
  jne    L173
L89:
  movss  0x0(%rbp),%xmm0
  movaps %xmm0,%xmm1
  subss  %xmm3,%xmm1
  movss  %xmm1,0x4(%rbp)
  addss  %xmm3,%xmm0
  movss  %xmm0,0x0(%rbp)
  cmp    $0x4,%ebx
  jg     L170
  je     L148
L98:
  movslq %r13d,%r13
  lea    (%r14,%r13,4),%rcx
  mov    %r15d,%edx
  mov    %rbp,%rsi
  mov    %ebx,%edi
  call   <dctsub@plt>
  jmp    L85
L170:
  movslq %r13d,%rax
  lea    (%r14,%rax,4),%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    L98
L148:
  mov    %r14,%rdx
  mov    %rbp,%rsi
  mov    $0x4,%edi
  call   <cftfsub@plt>
  jmp    L98
L137:
  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>
L56:
  movss  0x0(%rbp),%xmm0
  movss  0x4(%rbp),%xmm1
  movaps %xmm0,%xmm3
  subss  %xmm1,%xmm3
  addss  %xmm1,%xmm0
  movss  %xmm0,0x0(%rbp)
L132:
  lea    0x4(%rbp),%rax
  mov    $0x2,%edx
L22:
  movss  0x4(%rax),%xmm0
  movss  0x8(%rax),%xmm1
  movaps %xmm0,%xmm2
  subss  %xmm1,%xmm2
  movss  %xmm2,(%rax)
  addss  %xmm1,%xmm0
  movss  %xmm0,0x4(%rax)
  add    $0x2,%edx
  add    $0x8,%rax
  cmp    %edx,%ebx
  jg     L22
L117:
  movslq %ebx,%rbx
  movss  %xmm3,-0x4(%rbp,%rbx,4)
L85:
  add    $0x18,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
L31:
  mov    %r14,%rdx
  mov    %rbp,%rsi
  mov    $0x4,%edi
  call   <cftfsub@plt>
  jmp    L56
```

assistant: ```c
void lsx_ddct_f(int n, int isgn, float *a, int *ip, float *w) {
  int j, nw, nc;
  float 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;
  }
}
```