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

```asm
<convex_hull>:
  endbr64
  push   %rbp
  mov    %edi,%ecx
  mov    %rsp,%rbp
  sub    $0x20,%rsp
  mov    %edi,-0x14(%rbp)
  mov    %fs:0x28,%rax
  mov    %rax,-0x8(%rbp)
  xor    %eax,%eax
  movslq %edi,%rax
  mov    %rsp,%rdi
  lea    0xf(,%rax,4),%rax
  mov    %rax,%rdx
  and    $0xfffffffffffff000,%rax
  sub    %rax,%rdi
  and    $0xfffffffffffffff0,%rdx
  cmp    %rdi,%rsp
  je     L72
L223:
  sub    $0x1000,%rsp
  orq    $0x0,0xff8(%rsp)
  cmp    %rdi,%rsp
  jne    L223
L72:
  and    $0xfff,%edx
  sub    %rdx,%rsp
  test   %rdx,%rdx
  jne    L37
L239:
  mov    %rsp,%r8
  test   %ecx,%ecx
  jle    L159
  lea    -0x1(%rcx),%eax
  cmp    $0xe,%eax
  jbe    L154
  mov    %ecx,%edi
  mov    %rsi,%rdx
  pxor   %xmm5,%xmm5
  mov    %r8,%rax
  shr    $0x4,%edi
  pxor   %xmm3,%xmm3
  sub    $0x1,%edi
  shl    $0x4,%rdi
  lea    0x10(%rsi,%rdi,1),%rdi
L231:
  movdqu (%rdx),%xmm0
  movdqa %xmm5,%xmm2
  add    $0x10,%rdx
  add    $0x40,%rax
  pcmpgtb %xmm0,%xmm2
  movdqa %xmm0,%xmm1
  punpcklbw %xmm2,%xmm1
  punpckhbw %xmm2,%xmm0
  movdqa %xmm3,%xmm2
  pcmpgtw %xmm1,%xmm2
  movdqa %xmm1,%xmm4
  punpckhwd %xmm2,%xmm1
  punpcklwd %xmm2,%xmm4
  movdqa %xmm0,%xmm2
  movups %xmm1,-0x30(%rax)
  movdqa %xmm3,%xmm1
  pcmpgtw %xmm0,%xmm1
  movups %xmm4,-0x40(%rax)
  punpcklwd %xmm1,%xmm2
  punpckhwd %xmm1,%xmm0
  movups %xmm2,-0x20(%rax)
  movups %xmm0,-0x10(%rax)
  cmp    %rdi,%rdx
  jne    L231
  mov    %ecx,%eax
  and    $0xfffffff0,%eax
  test   $0xf,%cl
  je     L159
L71:
  movslq %eax,%rdi
  lea    (%r8,%rdi,4),%rdx
  movsbl (%rsi,%rdi,1),%edi
  mov    %edi,(%rdx)
  lea    0x1(%rax),%edi
  cmp    %edi,%ecx
  jle    L159
  movslq %edi,%rdi
  movsbl (%rsi,%rdi,1),%edi
  mov    %edi,0x4(%rdx)
  lea    0x2(%rax),%edi
  cmp    %edi,%ecx
  jle    L159
  movslq %edi,%rdi
  movsbl (%rsi,%rdi,1),%edi
  mov    %edi,0x8(%rdx)
  lea    0x3(%rax),%edi
  cmp    %edi,%ecx
  jle    L159
  movslq %edi,%rdi
  movsbl (%rsi,%rdi,1),%edi
  mov    %edi,0xc(%rdx)
  lea    0x4(%rax),%edi
  cmp    %edi,%ecx
  jle    L159
  movslq %edi,%rdi
  movsbl (%rsi,%rdi,1),%edi
  mov    %edi,0x10(%rdx)
  lea    0x5(%rax),%edi
  cmp    %edi,%ecx
  jle    L159
  movslq %edi,%rdi
  movsbl (%rsi,%rdi,1),%edi
  mov    %edi,0x14(%rdx)
  lea    0x6(%rax),%edi
  cmp    %edi,%ecx
  jle    L159
  movslq %edi,%rdi
  movsbl (%rsi,%rdi,1),%edi
  mov    %edi,0x18(%rdx)
  lea    0x7(%rax),%edi
  cmp    %edi,%ecx
  jle    L159
  movslq %edi,%rdi
  movsbl (%rsi,%rdi,1),%edi
  mov    %edi,0x1c(%rdx)
  lea    0x8(%rax),%edi
  cmp    %edi,%ecx
  jle    L159
  movslq %edi,%rdi
  movsbl (%rsi,%rdi,1),%edi
  mov    %edi,0x20(%rdx)
  lea    0x9(%rax),%edi
  cmp    %edi,%ecx
  jle    L159
  movslq %edi,%rdi
  movsbl (%rsi,%rdi,1),%edi
  mov    %edi,0x24(%rdx)
  lea    0xa(%rax),%edi
  cmp    %edi,%ecx
  jle    L159
  movslq %edi,%rdi
  movsbl (%rsi,%rdi,1),%edi
  mov    %edi,0x28(%rdx)
  lea    0xb(%rax),%edi
  cmp    %edi,%ecx
  jle    L159
  movslq %edi,%rdi
  movsbl (%rsi,%rdi,1),%edi
  mov    %edi,0x2c(%rdx)
  lea    0xc(%rax),%edi
  cmp    %edi,%ecx
  jle    L159
  movslq %edi,%rdi
  movsbl (%rsi,%rdi,1),%edi
  mov    %edi,0x30(%rdx)
  lea    0xd(%rax),%edi
  cmp    %edi,%ecx
  jle    L159
  movslq %edi,%rdi
  add    $0xe,%eax
  movsbl (%rsi,%rdi,1),%edi
  mov    %edi,0x34(%rdx)
  cmp    %eax,%ecx
  jle    L159
  cltq
  movsbl (%rsi,%rax,1),%eax
  mov    %eax,0x38(%rdx)
  nopl   0x0(%rax)
L159:
  xor    %ecx,%ecx
  mov    %r8,%rdx
  lea    -0x14(%rbp),%rsi
  mov    $0x245,%edi
  call   <_ada_use_c2phc@plt>
  mov    -0x8(%rbp),%rdx
  sub    %fs:0x28,%rdx
  jne    L214
  leave
  ret
  nopl   0x0(%rax)
L37:
  orq    $0x0,-0x8(%rsp,%rdx,1)
  jmp    L239
L154:
  xor    %eax,%eax
  jmp    L71
L214:
  call   <__stack_chk_fail@plt>
```

assistant: ```c
int convex_hull(int nc_pts, char *pts) {
  int fail, i;
  int points[nc_pts];
  double *c;
  for (i = 0; i < nc_pts; i++)
    points[i] = (int)pts[i];
  fail = _ada_use_c2phc(581, &nc_pts, points, c);
  return fail;
}
```