user: What would the C source look like for the assembly code provided here:

```asm
<dedisperse_lagged>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  sub    $0x38,%rsp
  mov    %rdi,%r14
  mov    %rdi,0x18(%rsp)
  mov    %rsi,%rbp
  mov    %rsi,0x20(%rsp)
  mov    %edx,%r15d
  mov    %ecx,%ebx
  mov    %ecx,0x2c(%rsp)
  cmp    $0x1,%edx
  setg   %dil
  movzbl %dil,%edi
  call   <assert@plt>
  test   %ebx,%ebx
  setg   %dil
  movzbl %dil,%edi
  call   <assert@plt>
  lea    -0x1(%r15,%rbx,1),%ebx
  movslq %ebx,%rbx
  mov    0x8(%r14),%rax
  sub    (%r14),%rax
  sar    $0x2,%rax
  cmp    %rbx,%rax
  setge  %dil
  movzbl %dil,%edi
  call   <assert@plt>
  mov    0x8(%rbp),%rax
  sub    0x0(%rbp),%rax
  sar    $0x2,%rax
  cmp    %rax,%rbx
  setle  %dil
  movzbl %dil,%edi
  call   <assert@plt>
  mov    %r15d,%edi
  call   <get_npass@plt>
  mov    %eax,%ebx
  mov    %eax,0x28(%rsp)
  mov    $0x1,%eax
  mov    %ebx,%ecx
  shl    %cl,%eax
  cmp    %r15d,%eax
  sete   %dil
  movzbl %dil,%edi
  call   <assert@plt>
  movl   $0x0,0x14(%rsp)
  mov    %r15d,%ebp
  mov    0x2c(%rsp),%r14d
  test   %ebx,%ebx
  jg     L44
  mov    0x20(%rsp),%rax
  mov    0x18(%rsp),%rsi
  mov    %rsi,0x20(%rsp)
  mov    %rax,0x18(%rsp)
L57:
  test   %r15d,%r15d
  jle    L23
  mov    0x2c(%rsp),%ebx
  shl    $0x2,%ebx
  mov    %r15d,%r15d
  mov    $0x0,%ebp
  mov    0x18(%rsp),%r12
  mov    0x20(%rsp),%r13
L36:
  mov    0x0(%r13,%rbp,8),%rsi
  mov    (%r12,%rbp,8),%rdi
  mov    %ebx,%edx
  call   <memcpy@plt>
  add    $0x1,%rbp
  add    $0x4,%ebx
  cmp    %r15,%rbp
  jne    L36
L23:
  add    $0x38,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
L53:
  movslq %ebp,%rax
  shl    $0x3,%rax
  mov    %rax,0x8(%rsp)
  mov    0x18(%rsp),%r13
  mov    0x20(%rsp),%r12
  mov    $0x0,%ebx
L20:
  mov    %ebx,%eax
  cltd
  idiv   %ebp
  mov    %eax,%r8d
  lea    (%rax,%r14,1),%ecx
  mov    %ebp,%edx
  mov    %r12,%rsi
  mov    %r13,%rdi
  call   <dedisperse_kernel_lagged@plt>
  add    %ebp,%ebx
  mov    0x8(%rsp),%rax
  add    %rax,%r13
  add    %rax,%r12
  cmp    %ebx,%r15d
  jg     L20
L30:
  mov    %ebp,%eax
  shr    $0x1f,%eax
  add    %ebp,%eax
  sar    %eax
  mov    %eax,%ebp
  addl   $0x1,0x14(%rsp)
  mov    0x14(%rsp),%eax
  cmp    %eax,0x28(%rsp)
  je     L57
  mov    0x18(%rsp),%rax
  mov    0x20(%rsp),%rdi
  mov    %rdi,0x18(%rsp)
  mov    %rax,0x20(%rsp)
L44:
  test   %r15d,%r15d
  jg     L53
  jmp    L30
```

assistant: ```c
void dedisperse_lagged(float **inin, float **outout, int nchan, int ndat) {
  assert(nchan >= 2);
  assert(ndat >= 1);
  assert(inin[1] - inin[0] >= nchan + ndat - 1);
  assert(outout[1] - outout[0] >= nchan + ndat - 1);
  int npass = get_npass(nchan);
  assert(nchan == (1 << npass));
  int bs = nchan;
  float **in = inin;
  float **out = outout;
  for (int i = 0; i < npass; i++) {
#pragma omp parallel for
    for (int j = 0; j < nchan; j += bs)
      dedisperse_kernel_lagged(in + j, out + j, bs, ndat + j / bs, j / bs);
    float **tmp = in;
    in = out;
    out = tmp;
    bs /= 2;
  }
  for (int j = 0; j < nchan; j++)
    memcpy(out[j], in[j], (ndat + j) * sizeof(float));
}
```