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

```asm
<dfct>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  sub    $0x38,%rsp
  mov    %edi,%r14d
  mov    %rsi,%r12
  mov    %rdx,%rbx
  mov    %rcx,0x18(%rsp)
  mov    %r8,0x10(%rsp)
  mov    (%rcx),%r15d
  lea    0x0(,%r15,8),%eax
  cmp    %edi,%eax
  jl     L231
L179:
  mov    0x18(%rsp),%rax
  mov    0x4(%rax),%eax
  mov    %eax,0xc(%rsp)
  add    %eax,%eax
  cmp    %r14d,%eax
  jl     L186
L213:
  mov    %r14d,%r13d
  sar    %r13d
  movslq %r13d,%rax
  movss  (%r12,%rax,4),%xmm0
  movss  (%r12),%xmm1
  movslq %r14d,%rdx
  lea    0x0(,%rdx,4),%rdi
  mov    %rdi,0x20(%rsp)
  lea    (%r12,%rdi,1),%rsi
  mov    %rsi,0x28(%rsp)
  movss  (%rsi),%xmm3
  movaps %xmm1,%xmm2
  addss  %xmm3,%xmm2
  subss  %xmm3,%xmm1
  movss  %xmm1,(%r12)
  movaps %xmm2,%xmm1
  subss  %xmm0,%xmm1
  movss  %xmm1,(%rbx)
  addss  %xmm2,%xmm0
  movss  %xmm0,(%rbx,%rax,4)
  cmp    $0x2,%r14d
  jle    L9
  mov    %r14d,%ebp
  sar    $0x2,%ebp
  cmp    $0x7,%r14d
  jle    L67
  lea    -0x4(,%rax,4),%rdx
  mov    %ebp,%esi
  neg    %rax
  lea    (%rdi,%rax,4),%rcx
  add    %r12,%rcx
  mov    $0x1,%eax
L8:
  movss  (%r12,%rax,4),%xmm2
  movss  (%rcx,%rdx,1),%xmm5
  movaps %xmm2,%xmm0
  addss  %xmm5,%xmm0
  movss  (%r12,%rdx,1),%xmm1
  movss  (%rcx,%rax,4),%xmm4
  movaps %xmm1,%xmm3
  addss  %xmm4,%xmm3
  subss  %xmm5,%xmm2
  movss  %xmm2,(%r12,%rax,4)
  subss  %xmm4,%xmm1
  movss  %xmm1,(%r12,%rdx,1)
  movaps %xmm0,%xmm1
  subss  %xmm3,%xmm1
  movss  %xmm1,(%rbx,%rax,4)
  addss  %xmm3,%xmm0
  movss  %xmm0,(%rbx,%rdx,1)
  add    $0x1,%rax
  sub    $0x4,%rdx
  cmp    %rsi,%rax
  jne    L8
L67:
  movslq %ebp,%rcx
  lea    (%r12,%rcx,4),%rax
  mov    %r14d,%edx
  sub    %ebp,%edx
  movslq %edx,%rdx
  lea    (%r12,%rdx,4),%rdx
  movss  (%rax),%xmm0
  addss  (%rdx),%xmm0
  movss  %xmm0,(%rbx,%rcx,4)
  movss  (%rax),%xmm0
  subss  (%rdx),%xmm0
  movss  %xmm0,(%rax)
  movslq %r15d,%r15
  mov    0x10(%rsp),%rax
  lea    (%rax,%r15,4),%r15
  mov    %r15,%rcx
  mov    0xc(%rsp),%edx
  mov    %r12,%rsi
  mov    %r13d,%edi
  call   <dctsub@plt>
  cmp    $0x4,%r13d
  jg     L72
  je     L59
  movss  (%r12),%xmm0
  subss  0x4(%r12),%xmm0
  mov    0x20(%rsp),%rax
  movss  %xmm0,-0x4(%r12,%rax,1)
  movss  0x4(%r12),%xmm0
  addss  (%r12),%xmm0
  movss  %xmm0,0x4(%r12)
  jmp    L117
L231:
  mov    %edi,%r15d
  sar    $0x3,%r15d
  mov    %r8,%rdx
  mov    %rcx,%rsi
  mov    %r15d,%edi
  call   <makewt@plt>
  jmp    L179
L186:
  mov    %r14d,%edi
  sar    %edi
  mov    %edi,0xc(%rsp)
  movslq %r15d,%rax
  mov    0x10(%rsp),%rsi
  lea    (%rsi,%rax,4),%rdx
  mov    0x18(%rsp),%rsi
  call   <makect@plt>
  jmp    L213
L72:
  mov    0x18(%rsp),%rax
  lea    0x8(%rax),%rsi
  mov    %r12,%rdx
  mov    %r13d,%edi
  call   <bitrv2@plt>
  mov    0x10(%rsp),%rdx
  mov    %r12,%rsi
  mov    %r13d,%edi
  call   <cftfsub@plt>
  mov    %r15,%rcx
  mov    0xc(%rsp),%edx
  mov    %r12,%rsi
  mov    %r13d,%edi
  call   <rftfsub@plt>
L82:
  movss  (%r12),%xmm0
  subss  0x4(%r12),%xmm0
  mov    0x20(%rsp),%rax
  movss  %xmm0,-0x4(%r12,%rax,1)
  movss  0x4(%r12),%xmm0
  addss  (%r12),%xmm0
  movss  %xmm0,0x4(%r12)
  lea    -0x2(%r13),%eax
  cltq
L189:
  movss  (%r12,%rax,4),%xmm0
  addss  0x4(%r12,%rax,4),%xmm0
  movss  %xmm0,0x4(%r12,%rax,8)
  movss  (%r12,%rax,4),%xmm0
  subss  0x4(%r12,%rax,4),%xmm0
  movss  %xmm0,-0x4(%r12,%rax,8)
  sub    $0x2,%rax
  cmp    $0x1,%eax
  jg     L189
L117:
  cmp    $0x1,%ebp
  jle    L201
  mov    $0x2,%r13d
  mov    0x18(%rsp),%rax
  add    $0x8,%rax
  mov    %rax,0x18(%rsp)
  jmp    L71
L59:
  mov    0x10(%rsp),%rdx
  mov    %r12,%rsi
  mov    $0x4,%edi
  call   <cftfsub@plt>
  jmp    L82
L209:
  mov    %rbx,%rdx
  mov    0x18(%rsp),%rsi
  mov    %ebp,%edi
  call   <bitrv2@plt>
  mov    0x10(%rsp),%rdx
  mov    %rbx,%rsi
  mov    %ebp,%edi
  call   <cftfsub@plt>
  mov    %r15,%rcx
  mov    0xc(%rsp),%edx
  mov    %rbx,%rsi
  mov    %ebp,%edi
  call   <rftfsub@plt>
L29:
  mov    %r14d,%eax
  sub    %r13d,%eax
  cltq
  movss  (%rbx),%xmm0
  subss  0x4(%rbx),%xmm0
  movss  %xmm0,(%r12,%rax,4)
  movslq %r13d,%rax
  movss  0x4(%rbx),%xmm0
  addss  (%rbx),%xmm0
  movss  %xmm0,(%r12,%rax,4)
L33:
  lea    0x0(,%r13,4),%eax
  cltq
  lea    0x0(,%rax,4),%rsi
  movslq %r13d,%rcx
  sub    %rcx,%rax
  lea    (%r12,%rax,4),%rdx
  mov    $0x2,%eax
L26:
  movss  (%rbx,%rax,4),%xmm0
  subss  0x4(%rbx,%rax,4),%xmm0
  movss  %xmm0,(%rdx)
  movss  (%rbx,%rax,4),%xmm0
  addss  0x4(%rbx,%rax,4),%xmm0
  movss  %xmm0,(%rdx,%rcx,8)
  add    $0x2,%rax
  add    %rsi,%rdx
  cmp    %eax,%ebp
  jg     L26
  add    %r13d,%r13d
  mov    %ebp,%esi
  sar    %esi
L112:
  lea    0x0(%rbp,%rbp,1),%eax
  cltq
  lea    (%rbx,%rax,4),%rcx
  mov    %rcx,%rdx
  movslq %ebp,%rdi
  neg    %rdi
  shl    $0x2,%rdi
  add    %rdi,%rcx
  mov    $0x0,%eax
L99:
  movss  (%rdx),%xmm0
  subss  (%rcx,%rax,4),%xmm0
  movss  %xmm0,(%rbx,%rax,4)
  movss  (%rdx),%xmm0
  addss  (%rcx,%rax,4),%xmm0
  movss  %xmm0,(%rdx,%rdi,1)
  add    $0x1,%rax
  sub    $0x4,%rdx
  cmp    %eax,%esi
  jg     L99
  add    %esi,%ebp
  movslq %ebp,%rbp
  movss  (%rbx,%rbp,4),%xmm0
  movslq %esi,%rax
  movss  %xmm0,(%rbx,%rax,4)
  cmp    $0x1,%esi
  jle    L223
  mov    %esi,%ebp
L71:
  mov    %r15,%rcx
  mov    0xc(%rsp),%edx
  mov    %rbx,%rsi
  mov    %ebp,%edi
  call   <dctsub@plt>
  cmp    $0x4,%ebp
  jg     L209
  je     L147
  mov    %r14d,%eax
  sub    %r13d,%eax
  cltq
  movss  (%rbx),%xmm0
  subss  0x4(%rbx),%xmm0
  movss  %xmm0,(%r12,%rax,4)
  movslq %r13d,%rax
  movss  (%rbx),%xmm0
  addss  0x4(%rbx),%xmm0
  movss  %xmm0,(%r12,%rax,4)
  cmp    $0x2,%ebp
  jg     L33
  add    %r13d,%r13d
  mov    %ebp,%esi
  sar    %esi
  test   %esi,%esi
  jg     L112
  lea    (%rsi,%rbp,1),%eax
  cltq
  movss  (%rbx,%rax,4),%xmm0
  movslq %esi,%rsi
  movss  %xmm0,(%rbx,%rsi,4)
L223:
  movss  (%rbx),%xmm0
  movslq %r13d,%r13
  movss  %xmm0,(%r12,%r13,4)
  movss  0x8(%rbx),%xmm0
  subss  0x4(%rbx),%xmm0
  mov    0x28(%rsp),%rax
  movss  %xmm0,(%rax)
  movss  0x8(%rbx),%xmm0
  addss  0x4(%rbx),%xmm0
L134:
  movss  %xmm0,(%r12)
  add    $0x38,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
L147:
  mov    0x10(%rsp),%rdx
  mov    %rbx,%rsi
  mov    $0x4,%edi
  call   <cftfsub@plt>
  jmp    L29
L201:
  mov    $0x2,%r13d
  jmp    L223
L9:
  movss  (%r12),%xmm0
  movss  %xmm0,0x4(%r12)
  movss  (%rbx),%xmm0
  movss  %xmm0,0x8(%r12)
  movss  0x4(%rbx),%xmm0
  jmp    L134
```

assistant: ```c
void dfct(int n, float *a, float *t, int *ip, float *w) {
  int j, k, l, m, mh, nw, nc;
  float xr, xi, yr, yi;
  nw = ip[0];
  if (n > (nw << 3)) {
    nw = n >> 3;
    makewt(nw, ip, w);
  }
  nc = ip[1];
  if (n > (nc << 1)) {
    nc = n >> 1;
    makect(nc, ip, w + nw);
  }
  m = n >> 1;
  yi = a[m];
  xi = a[0] + a[n];
  a[0] -= a[n];
  t[0] = xi - yi;
  t[m] = xi + yi;
  if (n > 2) {
    mh = m >> 1;
    for (j = 1; j < mh; j++) {
      k = m - j;
      xr = a[j] - a[n - j];
      xi = a[j] + a[n - j];
      yr = a[k] - a[n - k];
      yi = a[k] + a[n - k];
      a[j] = xr;
      a[k] = yr;
      t[j] = xi - yi;
      t[k] = xi + yi;
    }
    t[mh] = a[mh] + a[n - mh];
    a[mh] -= a[n - mh];
    dctsub(m, a, nc, w + nw);
    if (m > 4) {
      bitrv2(m, ip + 2, a);
      cftfsub(m, a, w);
      rftfsub(m, a, nc, w + nw);
    } else if (m == 4) {
      cftfsub(m, a, w);
    }
    a[n - 1] = a[0] - a[1];
    a[1] = a[0] + a[1];
    for (j = m - 2; j >= 2; j -= 2) {
      a[2 * j + 1] = a[j] + a[j + 1];
      a[2 * j - 1] = a[j] - a[j + 1];
    }
    l = 2;
    m = mh;
    while (m >= 2) {
      dctsub(m, t, nc, w + nw);
      if (m > 4) {
        bitrv2(m, ip + 2, t);
        cftfsub(m, t, w);
        rftfsub(m, t, nc, w + nw);
      } else if (m == 4) {
        cftfsub(m, t, w);
      }
      a[n - l] = t[0] - t[1];
      a[l] = t[0] + t[1];
      k = 0;
      for (j = 2; j < m; j += 2) {
        k += l << 2;
        a[k - l] = t[j] - t[j + 1];
        a[k + l] = t[j] + t[j + 1];
      }
      l <<= 1;
      mh = m >> 1;
      for (j = 0; j < mh; j++) {
        k = m - j;
        t[j] = t[m + k] - t[m + j];
        t[k] = t[m + k] + t[m + j];
      }
      t[mh] = t[m + mh];
      m = mh;
    }
    a[l] = t[0];
    a[n] = t[2] - t[1];
    a[0] = t[2] + t[1];
  } else {
    a[1] = a[0];
    a[2] = t[0];
    a[0] = t[1];
  }
}
```