user: What is the c source code of the assembly code below:

```asm
<neoscrypt_chacha>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  mov    %rdi,%r14
  mov    %rdi,-0x8(%rsp)
  mov    %esi,-0x4c(%rsp)
  mov    (%rdi),%r12d
  mov    %r12d,-0x40(%rsp)
  mov    0x4(%rdi),%edi
  mov    %edi,-0x3c(%rsp)
  mov    0x8(%r14),%ebp
  mov    %ebp,-0x38(%rsp)
  mov    0xc(%r14),%edx
  mov    %edx,-0x34(%rsp)
  mov    0x10(%r14),%r10d
  mov    %r10d,-0x30(%rsp)
  mov    0x14(%r14),%r13d
  mov    %r13d,-0x2c(%rsp)
  mov    0x18(%r14),%ebx
  mov    %ebx,-0x28(%rsp)
  mov    0x1c(%r14),%r15d
  mov    %r15d,-0x24(%rsp)
  mov    0x20(%r14),%ecx
  mov    %ecx,-0x20(%rsp)
  mov    0x24(%r14),%eax
  mov    %eax,-0x1c(%rsp)
  mov    0x28(%r14),%r11d
  mov    %r11d,-0x48(%rsp)
  mov    0x2c(%r14),%r8d
  mov    %r8d,-0x44(%rsp)
  mov    0x30(%r14),%r11d
  mov    %r11d,-0x18(%rsp)
  mov    0x34(%r14),%r9d
  mov    %r9d,-0x14(%rsp)
  mov    0x38(%r14),%r8d
  mov    %r8d,-0x10(%rsp)
  mov    0x3c(%r14),%r14d
  mov    %r14d,-0xc(%rsp)
  test   %esi,%esi
  je     L12
  mov    -0x44(%rsp),%esi
  mov    %esi,-0x54(%rsp)
  mov    -0x48(%rsp),%esi
  mov    %esi,-0x58(%rsp)
  mov    %ebp,%esi
L21:
  add    %r10d,%r12d
  xor    %r12d,%r11d
  mov    %r11d,%ebp
  shl    $0x10,%ebp
  sar    $0x10,%r11d
  or     %ebp,%r11d
  add    %r11d,%ecx
  xor    %ecx,%r10d
  mov    %r10d,%ebp
  shl    $0xc,%ebp
  sar    $0x14,%r10d
  or     %ebp,%r10d
  add    %r10d,%r12d
  xor    %r12d,%r11d
  mov    %r11d,%ebp
  shl    $0x8,%ebp
  sar    $0x18,%r11d
  or     %ebp,%r11d
  add    %r11d,%ecx
  mov    %ecx,-0x60(%rsp)
  xor    %ecx,%r10d
  mov    %r10d,%ebp
  shl    $0x7,%ebp
  mov    %ebp,%ecx
  sar    $0x19,%r10d
  or     %r10d,%ecx
  mov    %ecx,-0x50(%rsp)
  add    %r13d,%edi
  xor    %edi,%r9d
  mov    %r9d,%ebp
  shl    $0x10,%ebp
  sar    $0x10,%r9d
  or     %ebp,%r9d
  add    %r9d,%eax
  xor    %eax,%r13d
  mov    %r13d,%ebp
  shl    $0xc,%ebp
  sar    $0x14,%r13d
  or     %ebp,%r13d
  add    %r13d,%edi
  xor    %edi,%r9d
  mov    %r9d,%ebp
  shl    $0x8,%ebp
  mov    %ebp,%ecx
  sar    $0x18,%r9d
  or     %r9d,%ecx
  add    %ecx,%eax
  mov    %eax,-0x5c(%rsp)
  xor    %eax,%r13d
  mov    %r13d,%r9d
  shl    $0x7,%r9d
  sar    $0x19,%r13d
  or     %r13d,%r9d
  add    %ebx,%esi
  xor    %esi,%r8d
  mov    %r8d,%ebp
  shl    $0x10,%ebp
  sar    $0x10,%r8d
  or     %ebp,%r8d
  mov    -0x58(%rsp),%ebp
  add    %r8d,%ebp
  xor    %ebp,%ebx
  mov    %ebx,%r13d
  shl    $0xc,%r13d
  sar    $0x14,%ebx
  or     %r13d,%ebx
  add    %ebx,%esi
  xor    %esi,%r8d
  mov    %r8d,%r13d
  shl    $0x8,%r13d
  mov    %r13d,%eax
  sar    $0x18,%r8d
  or     %r8d,%eax
  add    %eax,%ebp
  xor    %ebp,%ebx
  mov    %ebx,%r8d
  shl    $0x7,%r8d
  mov    %r8d,%r10d
  sar    $0x19,%ebx
  or     %ebx,%r10d
  add    %r15d,%edx
  xor    %edx,%r14d
  mov    %r14d,%r8d
  shl    $0x10,%r8d
  sar    $0x10,%r14d
  or     %r8d,%r14d
  mov    -0x54(%rsp),%ebx
  add    %r14d,%ebx
  xor    %ebx,%r15d
  mov    %r15d,%r8d
  shl    $0xc,%r8d
  sar    $0x14,%r15d
  or     %r8d,%r15d
  add    %r15d,%edx
  xor    %edx,%r14d
  mov    %r14d,%r13d
  shl    $0x8,%r13d
  sar    $0x18,%r14d
  or     %r14d,%r13d
  add    %r13d,%ebx
  xor    %ebx,%r15d
  mov    %r15d,%r8d
  shl    $0x7,%r8d
  sar    $0x19,%r15d
  or     %r15d,%r8d
  add    %r9d,%r12d
  xor    %r12d,%r13d
  mov    %r13d,%r14d
  shl    $0x10,%r14d
  sar    $0x10,%r13d
  or     %r14d,%r13d
  add    %r13d,%ebp
  xor    %ebp,%r9d
  mov    %r9d,%r14d
  shl    $0xc,%r14d
  sar    $0x14,%r9d
  or     %r14d,%r9d
  add    %r9d,%r12d
  xor    %r12d,%r13d
  mov    %r13d,%r14d
  shl    $0x8,%r14d
  sar    $0x18,%r13d
  or     %r13d,%r14d
  add    %r14d,%ebp
  mov    %ebp,-0x58(%rsp)
  xor    %ebp,%r9d
  mov    %r9d,%r13d
  shl    $0x7,%r13d
  sar    $0x19,%r9d
  or     %r9d,%r13d
  add    %r10d,%edi
  xor    %edi,%r11d
  mov    %r11d,%r9d
  shl    $0x10,%r9d
  sar    $0x10,%r11d
  or     %r9d,%r11d
  add    %r11d,%ebx
  xor    %ebx,%r10d
  mov    %r10d,%r9d
  shl    $0xc,%r9d
  sar    $0x14,%r10d
  or     %r9d,%r10d
  add    %r10d,%edi
  xor    %edi,%r11d
  mov    %r11d,%r9d
  shl    $0x8,%r9d
  sar    $0x18,%r11d
  or     %r9d,%r11d
  add    %r11d,%ebx
  mov    %ebx,-0x54(%rsp)
  xor    %ebx,%r10d
  mov    %r10d,%ebx
  shl    $0x7,%ebx
  sar    $0x19,%r10d
  or     %r10d,%ebx
  add    %r8d,%esi
  xor    %esi,%ecx
  mov    %ecx,%r9d
  shl    $0x10,%r9d
  sar    $0x10,%ecx
  or     %ecx,%r9d
  mov    -0x60(%rsp),%r15d
  lea    (%r15,%r9,1),%ecx
  xor    %ecx,%r8d
  mov    %r8d,%r15d
  shl    $0xc,%r15d
  sar    $0x14,%r8d
  or     %r15d,%r8d
  add    %r8d,%esi
  xor    %esi,%r9d
  mov    %r9d,%r15d
  shl    $0x8,%r15d
  sar    $0x18,%r9d
  or     %r15d,%r9d
  add    %r9d,%ecx
  xor    %ecx,%r8d
  mov    %r8d,%r15d
  shl    $0x7,%r15d
  sar    $0x19,%r8d
  or     %r8d,%r15d
  mov    -0x50(%rsp),%r10d
  add    %r10d,%edx
  xor    %edx,%eax
  mov    %eax,%r8d
  shl    $0x10,%r8d
  sar    $0x10,%eax
  or     %eax,%r8d
  mov    -0x5c(%rsp),%eax
  add    %r8d,%eax
  xor    %eax,%r10d
  mov    %r10d,%ebp
  shl    $0xc,%r10d
  sar    $0x14,%ebp
  or     %ebp,%r10d
  add    %r10d,%edx
  xor    %edx,%r8d
  mov    %r8d,%ebp
  shl    $0x8,%ebp
  sar    $0x18,%r8d
  or     %ebp,%r8d
  add    %r8d,%eax
  xor    %eax,%r10d
  mov    %r10d,%ebp
  shl    $0x7,%ebp
  sar    $0x19,%r10d
  or     %ebp,%r10d
  subl   $0x2,-0x4c(%rsp)
  jne    L21
L4:
  mov    -0x40(%rsp),%ebp
  add    %r12d,%ebp
  mov    -0x8(%rsp),%r12
  mov    %ebp,(%r12)
  add    -0x3c(%rsp),%edi
  mov    %edi,0x4(%r12)
  add    -0x38(%rsp),%esi
  mov    %esi,0x8(%r12)
  add    -0x34(%rsp),%edx
  mov    %edx,0xc(%r12)
  mov    -0x30(%rsp),%edx
  add    %r10d,%edx
  mov    %edx,0x10(%r12)
  mov    -0x2c(%rsp),%edx
  add    %r13d,%edx
  mov    %edx,0x14(%r12)
  mov    -0x28(%rsp),%edx
  add    %ebx,%edx
  mov    %edx,0x18(%r12)
  mov    -0x24(%rsp),%edx
  add    %r15d,%edx
  mov    %edx,0x1c(%r12)
  mov    -0x20(%rsp),%edx
  add    %ecx,%edx
  mov    %edx,0x20(%r12)
  add    -0x1c(%rsp),%eax
  mov    %eax,0x24(%r12)
  mov    -0x48(%rsp),%eax
  add    -0x58(%rsp),%eax
  mov    %eax,0x28(%r12)
  mov    -0x44(%rsp),%eax
  add    -0x54(%rsp),%eax
  mov    %eax,0x2c(%r12)
  mov    -0x18(%rsp),%eax
  add    %r11d,%eax
  mov    %eax,0x30(%r12)
  mov    -0x14(%rsp),%eax
  add    %r9d,%eax
  mov    %eax,0x34(%r12)
  mov    -0x10(%rsp),%eax
  add    %r8d,%eax
  mov    %eax,0x38(%r12)
  mov    -0xc(%rsp),%eax
  add    %r14d,%eax
  mov    %eax,0x3c(%r12)
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
L12:
  mov    -0xc(%rsp),%r14d
  mov    -0x10(%rsp),%r8d
  mov    -0x14(%rsp),%r9d
  mov    -0x18(%rsp),%r11d
  mov    -0x44(%rsp),%eax
  mov    %eax,-0x54(%rsp)
  mov    -0x48(%rsp),%eax
  mov    %eax,-0x58(%rsp)
  mov    -0x1c(%rsp),%eax
  mov    -0x20(%rsp),%ecx
  mov    -0x24(%rsp),%r15d
  mov    -0x28(%rsp),%ebx
  mov    -0x2c(%rsp),%r13d
  mov    -0x30(%rsp),%r10d
  mov    -0x34(%rsp),%edx
  mov    -0x38(%rsp),%esi
  mov    -0x3c(%rsp),%edi
  mov    -0x40(%rsp),%r12d
  jmp    L4
```

assistant: ```c
void neoscrypt_chacha(uint *X, uint rounds) {
  uint x0, x1, x2, x3, x4, x5, x6, x7, x8, x9, x10, x11, x12, x13, x14, x15, t;
  x0 = X[0];
  x1 = X[1];
  x2 = X[2];
  x3 = X[3];
  x4 = X[4];
  x5 = X[5];
  x6 = X[6];
  x7 = X[7];
  x8 = X[8];
  x9 = X[9];
  x10 = X[10];
  x11 = X[11];
  x12 = X[12];
  x13 = X[13];
  x14 = X[14];
  x15 = X[15];
  for (; rounds; rounds -= 2) {
    x0 += x4;
    t = x12 ^ x0;
    x12 = (((t) << (16)) | ((t) >> (32 - 16)));
    x8 += x12;
    t = x4 ^ x8;
    x4 = (((t) << (12)) | ((t) >> (32 - 12)));
    x0 += x4;
    t = x12 ^ x0;
    x12 = (((t) << (8)) | ((t) >> (32 - 8)));
    x8 += x12;
    t = x4 ^ x8;
    x4 = (((t) << (7)) | ((t) >> (32 - 7)));
    ;
    x1 += x5;
    t = x13 ^ x1;
    x13 = (((t) << (16)) | ((t) >> (32 - 16)));
    x9 += x13;
    t = x5 ^ x9;
    x5 = (((t) << (12)) | ((t) >> (32 - 12)));
    x1 += x5;
    t = x13 ^ x1;
    x13 = (((t) << (8)) | ((t) >> (32 - 8)));
    x9 += x13;
    t = x5 ^ x9;
    x5 = (((t) << (7)) | ((t) >> (32 - 7)));
    ;
    x2 += x6;
    t = x14 ^ x2;
    x14 = (((t) << (16)) | ((t) >> (32 - 16)));
    x10 += x14;
    t = x6 ^ x10;
    x6 = (((t) << (12)) | ((t) >> (32 - 12)));
    x2 += x6;
    t = x14 ^ x2;
    x14 = (((t) << (8)) | ((t) >> (32 - 8)));
    x10 += x14;
    t = x6 ^ x10;
    x6 = (((t) << (7)) | ((t) >> (32 - 7)));
    ;
    x3 += x7;
    t = x15 ^ x3;
    x15 = (((t) << (16)) | ((t) >> (32 - 16)));
    x11 += x15;
    t = x7 ^ x11;
    x7 = (((t) << (12)) | ((t) >> (32 - 12)));
    x3 += x7;
    t = x15 ^ x3;
    x15 = (((t) << (8)) | ((t) >> (32 - 8)));
    x11 += x15;
    t = x7 ^ x11;
    x7 = (((t) << (7)) | ((t) >> (32 - 7)));
    ;
    x0 += x5;
    t = x15 ^ x0;
    x15 = (((t) << (16)) | ((t) >> (32 - 16)));
    x10 += x15;
    t = x5 ^ x10;
    x5 = (((t) << (12)) | ((t) >> (32 - 12)));
    x0 += x5;
    t = x15 ^ x0;
    x15 = (((t) << (8)) | ((t) >> (32 - 8)));
    x10 += x15;
    t = x5 ^ x10;
    x5 = (((t) << (7)) | ((t) >> (32 - 7)));
    ;
    x1 += x6;
    t = x12 ^ x1;
    x12 = (((t) << (16)) | ((t) >> (32 - 16)));
    x11 += x12;
    t = x6 ^ x11;
    x6 = (((t) << (12)) | ((t) >> (32 - 12)));
    x1 += x6;
    t = x12 ^ x1;
    x12 = (((t) << (8)) | ((t) >> (32 - 8)));
    x11 += x12;
    t = x6 ^ x11;
    x6 = (((t) << (7)) | ((t) >> (32 - 7)));
    ;
    x2 += x7;
    t = x13 ^ x2;
    x13 = (((t) << (16)) | ((t) >> (32 - 16)));
    x8 += x13;
    t = x7 ^ x8;
    x7 = (((t) << (12)) | ((t) >> (32 - 12)));
    x2 += x7;
    t = x13 ^ x2;
    x13 = (((t) << (8)) | ((t) >> (32 - 8)));
    x8 += x13;
    t = x7 ^ x8;
    x7 = (((t) << (7)) | ((t) >> (32 - 7)));
    ;
    x3 += x4;
    t = x14 ^ x3;
    x14 = (((t) << (16)) | ((t) >> (32 - 16)));
    x9 += x14;
    t = x4 ^ x9;
    x4 = (((t) << (12)) | ((t) >> (32 - 12)));
    x3 += x4;
    t = x14 ^ x3;
    x14 = (((t) << (8)) | ((t) >> (32 - 8)));
    x9 += x14;
    t = x4 ^ x9;
    x4 = (((t) << (7)) | ((t) >> (32 - 7)));
    ;
  }
  X[0] += x0;
  X[1] += x1;
  X[2] += x2;
  X[3] += x3;
  X[4] += x4;
  X[5] += x5;
  X[6] += x6;
  X[7] += x7;
  X[8] += x8;
  X[9] += x9;
  X[10] += x10;
  X[11] += x11;
  X[12] += x12;
  X[13] += x13;
  X[14] += x14;
  X[15] += x15;
}
```