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

```asm
<passf4>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  mov    %edi,-0x34(%rsp)
  mov    %esi,-0x38(%rsp)
  mov    %rdx,%r12
  mov    %rcx,%r13
  mov    0x38(%rsp),%rdx
  mov    %edi,%ebx
  cmp    $0x2,%edi
  je     L51
  test   %esi,%esi
  jle    L4
  lea    (%rdi,%rdi,1),%r10d
  lea    (%r10,%rdi,1),%edi
  imul   %ebx,%esi
  mov    %esi,%eax
  lea    (%rsi,%rsi,1),%ecx
  lea    (%rcx,%rsi,1),%esi
  movl   $0x0,-0x3c(%rsp)
  movl   $0x0,-0x40(%rsp)
  lea    -0x1(%rbx),%r15d
  movslq %r10d,%r11
  mov    %r11,-0x30(%rsp)
  movslq %ebx,%rbx
  mov    %rbx,-0x28(%rsp)
  movslq %edi,%rdi
  mov    %rdi,-0x20(%rsp)
  cltq
  mov    %rax,-0x18(%rsp)
  movslq %ecx,%rax
  mov    %rax,-0x10(%rsp)
  movslq %esi,%rax
  mov    %rax,-0x8(%rsp)
  jmp    L16
L51:
  mov    -0x38(%rsp),%ebx
  test   %ebx,%ebx
  jle    L4
  lea    (%rbx,%rbx,1),%ecx
  lea    0x0(,%rbx,4),%esi
  lea    (%rcx,%rbx,1),%edx
  add    %edx,%edx
  mov    %r12,%rax
  lea    -0x1(%rbx),%edi
  shl    $0x5,%rdi
  lea    0x20(%r12,%rdi,1),%rdi
  movslq %esi,%rsi
  pxor   %xmm6,%xmm6
  cvtsi2ssl 0x40(%rsp),%xmm6
  movslq %ecx,%rcx
  movslq %edx,%rdx
L62:
  movss  0x4(%rax),%xmm2
  movss  0x14(%rax),%xmm0
  movaps %xmm2,%xmm4
  subss  %xmm0,%xmm4
  addss  %xmm0,%xmm2
  movss  0x1c(%rax),%xmm1
  movss  0xc(%rax),%xmm8
  movaps %xmm1,%xmm9
  addss  %xmm8,%xmm9
  movss  (%rax),%xmm3
  movss  0x10(%rax),%xmm0
  movaps %xmm3,%xmm5
  subss  %xmm0,%xmm5
  addss  %xmm0,%xmm3
  movss  0x8(%rax),%xmm0
  movss  0x18(%rax),%xmm7
  movaps %xmm0,%xmm10
  addss  %xmm7,%xmm10
  movaps %xmm3,%xmm11
  addss  %xmm10,%xmm11
  movss  %xmm11,0x0(%r13)
  subss  %xmm10,%xmm3
  movss  %xmm3,0x0(%r13,%rsi,4)
  movaps %xmm2,%xmm3
  addss  %xmm9,%xmm3
  movss  %xmm3,0x4(%r13)
  subss  %xmm9,%xmm2
  movss  %xmm2,0x4(%r13,%rsi,4)
  subss  %xmm8,%xmm1
  mulss  %xmm6,%xmm1
  movaps %xmm1,%xmm2
  addss  %xmm5,%xmm2
  movss  %xmm2,0x0(%r13,%rcx,4)
  subss  %xmm1,%xmm5
  movss  %xmm5,0x0(%r13,%rdx,4)
  subss  %xmm7,%xmm0
  mulss  %xmm6,%xmm0
  movaps %xmm0,%xmm1
  addss  %xmm4,%xmm1
  movss  %xmm1,0x4(%r13,%rcx,4)
  subss  %xmm0,%xmm4
  movss  %xmm4,0x4(%r13,%rdx,4)
  add    $0x20,%rax
  add    $0x8,%r13
  cmp    %rdi,%rax
  jne    L62
L4:
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
L38:
  mov    -0x3c(%rsp),%edi
  lea    0x0(,%rdi,4),%eax
  cltq
  lea    (%r12,%rax,4),%r14
  mov    -0x30(%rsp),%rsi
  lea    (%rsi,%rax,1),%rcx
  lea    (%r12,%rcx,4),%rbp
  mov    -0x28(%rsp),%rbx
  lea    (%rbx,%rax,1),%rcx
  lea    (%r12,%rcx,4),%rbx
  add    -0x20(%rsp),%rax
  lea    (%r12,%rax,4),%r11
  movslq %edi,%rax
  lea    0x0(%r13,%rax,4),%r10
  mov    -0x18(%rsp),%rsi
  lea    (%rsi,%rax,1),%rcx
  lea    0x0(%r13,%rcx,4),%rdi
  mov    -0x10(%rsp),%rsi
  lea    (%rsi,%rax,1),%rcx
  lea    0x0(%r13,%rcx,4),%rsi
  add    -0x8(%rsp),%rax
  lea    0x0(%r13,%rax,4),%rcx
  mov    $0x0,%eax
  pxor   %xmm1,%xmm1
  cvtsi2ssl 0x40(%rsp),%xmm1
L9:
  movss  0x4(%r14,%rax,4),%xmm0
  movss  0x4(%rbp,%rax,4),%xmm3
  movaps %xmm0,%xmm2
  subss  %xmm3,%xmm2
  addss  %xmm3,%xmm0
  movss  0x4(%rbx,%rax,4),%xmm8
  movss  0x4(%r11,%rax,4),%xmm4
  movaps %xmm8,%xmm9
  addss  %xmm4,%xmm9
  movss  (%r14,%rax,4),%xmm5
  movss  0x0(%rbp,%rax,4),%xmm3
  movaps %xmm5,%xmm6
  subss  %xmm3,%xmm6
  addss  %xmm3,%xmm5
  movss  (%rbx,%rax,4),%xmm3
  movss  (%r11,%rax,4),%xmm7
  movaps %xmm3,%xmm10
  addss  %xmm7,%xmm10
  movaps %xmm5,%xmm11
  addss  %xmm10,%xmm11
  movss  %xmm11,(%r10,%rax,4)
  subss  %xmm10,%xmm5
  movaps %xmm0,%xmm10
  addss  %xmm9,%xmm10
  movss  %xmm10,0x4(%r10,%rax,4)
  subss  %xmm9,%xmm0
  subss  %xmm8,%xmm4
  mulss  %xmm1,%xmm4
  movaps %xmm4,%xmm8
  addss  %xmm6,%xmm8
  subss  %xmm4,%xmm6
  subss  %xmm7,%xmm3
  mulss  %xmm1,%xmm3
  movaps %xmm3,%xmm4
  addss  %xmm2,%xmm4
  subss  %xmm3,%xmm2
  movaps %xmm8,%xmm3
  mulss  (%r8,%rax,4),%xmm3
  movaps %xmm1,%xmm7
  mulss  0x4(%r8,%rax,4),%xmm7
  mulss  %xmm4,%xmm7
  subss  %xmm7,%xmm3
  movss  %xmm3,(%rdi,%rax,4)
  movaps %xmm1,%xmm3
  mulss  0x4(%r8,%rax,4),%xmm3
  mulss  %xmm8,%xmm3
  mulss  (%r8,%rax,4),%xmm4
  addss  %xmm4,%xmm3
  movss  %xmm3,0x4(%rdi,%rax,4)
  movaps %xmm5,%xmm3
  mulss  (%r9,%rax,4),%xmm3
  movaps %xmm1,%xmm4
  mulss  0x4(%r9,%rax,4),%xmm4
  mulss  %xmm0,%xmm4
  subss  %xmm4,%xmm3
  movss  %xmm3,(%rsi,%rax,4)
  movaps %xmm1,%xmm3
  mulss  0x4(%r9,%rax,4),%xmm3
  mulss  %xmm5,%xmm3
  mulss  (%r9,%rax,4),%xmm0
  addss  %xmm3,%xmm0
  movss  %xmm0,0x4(%rsi,%rax,4)
  movaps %xmm6,%xmm0
  mulss  (%rdx,%rax,4),%xmm0
  movaps %xmm1,%xmm3
  mulss  0x4(%rdx,%rax,4),%xmm3
  mulss  %xmm2,%xmm3
  subss  %xmm3,%xmm0
  movss  %xmm0,(%rcx,%rax,4)
  movaps %xmm1,%xmm0
  mulss  0x4(%rdx,%rax,4),%xmm0
  mulss  %xmm6,%xmm0
  mulss  (%rdx,%rax,4),%xmm2
  addss  %xmm2,%xmm0
  movss  %xmm0,0x4(%rcx,%rax,4)
  add    $0x2,%rax
  cmp    %eax,%r15d
  jg     L9
L42:
  addl   $0x1,-0x40(%rsp)
  mov    -0x40(%rsp),%eax
  mov    -0x34(%rsp),%esi
  add    %esi,-0x3c(%rsp)
  cmp    %eax,-0x38(%rsp)
  je     L4
L16:
  test   %r15d,%r15d
  jg     L38
  jmp    L42
```

assistant: ```c
void passf4(int ido, int l1, const float cc[], float ch[], const float wa1[], const float wa2[], const float wa3[], int isign) {
  int i, k, ac, ah;
  float ci2, ci3, ci4, cr2, cr3, cr4, ti1, ti2, ti3, ti4, tr1, tr2, tr3, tr4;
  if (ido == 2) {
    for (k = 0; k < l1; k++) {
      ac = 4 * k * ido + 1;
      ti1 = cc[ac] - cc[ac + 2 * ido];
      ti2 = cc[ac] + cc[ac + 2 * ido];
      tr4 = cc[ac + 3 * ido] - cc[ac + ido];
      ti3 = cc[ac + ido] + cc[ac + 3 * ido];
      tr1 = cc[ac - 1] - cc[ac + 2 * ido - 1];
      tr2 = cc[ac - 1] + cc[ac + 2 * ido - 1];
      ti4 = cc[ac + ido - 1] - cc[ac + 3 * ido - 1];
      tr3 = cc[ac + ido - 1] + cc[ac + 3 * ido - 1];
      ah = k * ido;
      ch[ah] = tr2 + tr3;
      ch[ah + 2 * l1 * ido] = tr2 - tr3;
      ch[ah + 1] = ti2 + ti3;
      ch[ah + 2 * l1 * ido + 1] = ti2 - ti3;
      ch[ah + l1 * ido] = tr1 + isign * tr4;
      ch[ah + 3 * l1 * ido] = tr1 - isign * tr4;
      ch[ah + l1 * ido + 1] = ti1 + isign * ti4;
      ch[ah + 3 * l1 * ido + 1] = ti1 - isign * ti4;
    }
  } else {
    for (k = 0; k < l1; k++) {
      for (i = 0; i < ido - 1; i += 2) {
        ac = i + 1 + 4 * k * ido;
        ti1 = cc[ac] - cc[ac + 2 * ido];
        ti2 = cc[ac] + cc[ac + 2 * ido];
        ti3 = cc[ac + ido] + cc[ac + 3 * ido];
        tr4 = cc[ac + 3 * ido] - cc[ac + ido];
        tr1 = cc[ac - 1] - cc[ac + 2 * ido - 1];
        tr2 = cc[ac - 1] + cc[ac + 2 * ido - 1];
        ti4 = cc[ac + ido - 1] - cc[ac + 3 * ido - 1];
        tr3 = cc[ac + ido - 1] + cc[ac + 3 * ido - 1];
        ah = i + k * ido;
        ch[ah] = tr2 + tr3;
        cr3 = tr2 - tr3;
        ch[ah + 1] = ti2 + ti3;
        ci3 = ti2 - ti3;
        cr2 = tr1 + isign * tr4;
        cr4 = tr1 - isign * tr4;
        ci2 = ti1 + isign * ti4;
        ci4 = ti1 - isign * ti4;
        ch[ah + l1 * ido] = wa1[i] * cr2 - isign * wa1[i + 1] * ci2;
        ch[ah + l1 * ido + 1] = wa1[i] * ci2 + isign * wa1[i + 1] * cr2;
        ch[ah + 2 * l1 * ido] = wa2[i] * cr3 - isign * wa2[i + 1] * ci3;
        ch[ah + 2 * l1 * ido + 1] = wa2[i] * ci3 + isign * wa2[i + 1] * cr3;
        ch[ah + 3 * l1 * ido] = wa3[i] * cr4 - isign * wa3[i + 1] * ci4;
        ch[ah + 3 * l1 * ido + 1] = wa3[i] * ci4 + isign * wa3[i + 1] * cr4;
      }
    }
  }
}
```