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

```asm
<drawline>:
  endbr64
  push   %r15
  mov    %r8d,%eax
  mov    %ecx,%r10d
  push   %r14
  mov    %esi,%r14d
  push   %r13
  push   %r12
  push   %rbp
  mov    %edx,%ebp
  mov    %ecx,%edx
  push   %rbx
  sub    %r9d,%edx
  mov    %r8d,%ebx
  mov    %edx,%ecx
  sub    $0x28,%rsp
  mov    0x60(%rsp),%r12d
  mov    %rdi,(%rsp)
  sub    %r12d,%eax
  or     %eax,%ecx
  je     L25
  mov    %r9d,%ecx
  mov    %r9d,%r15d
  sub    %r10d,%ecx
  test   %edx,%edx
  cmovs  %ecx,%edx
  mov    %r12d,%ecx
  sub    %r8d,%ecx
  test   %eax,%eax
  cmovs  %ecx,%eax
  cmp    %eax,%edx
  jge    L135
  cmp    %r12d,%r8d
  jle    L63
L129:
  sub    %r15d,%r10d
  movslq %ebp,%rax
  mov    %r12d,%r8d
  xor    %r13d,%r13d
  mov    %r10d,0x14(%rsp)
  mov    %r12d,%r10d
  imul   %r14d,%r10d
  mov    %rax,0x18(%rsp)
  nopw   0x0(%rax,%rax,1)
L94:
  test   %ebp,%ebp
  jle    L3
  mov    %r13d,%eax
  mov    %ebx,%esi
  mov    %r8d,0x10(%rsp)
  sub    %r12d,%esi
  cltd
  mov    %r10d,0xc(%rsp)
  idiv   %esi
  mov    0x18(%rsp),%rdx
  mov    $0xff,%esi
  lea    (%rax,%r15,1),%edi
  imul   %ebp,%edi
  add    %r10d,%edi
  movslq %edi,%rdi
  add    (%rsp),%rdi
  call   <memset@plt>
  mov    0x10(%rsp),%r8d
  mov    0xc(%rsp),%r10d
L3:
  add    $0x1,%r8d
  add    0x14(%rsp),%r13d
  add    %r14d,%r10d
  cmp    %ebx,%r8d
  jle    L94
L142:
  add    $0x28,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
  nopl   0x0(%rax,%rax,1)
L135:
  cmp    %r9d,%r10d
  jg     L97
L35:
  mov    %r10d,%r11d
  lea    -0x1(%rbp),%eax
  sub    %ebx,%r12d
  mov    %r10d,%r13d
  imul   %ebp,%r11d
  mov    %eax,0x18(%rsp)
  mov    %r12d,0x14(%rsp)
  xor    %r12d,%r12d
  nopl   (%rax)
L48:
  test   %ebp,%ebp
  jle    L79
  mov    %r12d,%eax
  mov    %r15d,%edi
  mov    0x18(%rsp),%esi
  mov    %r10d,0x10(%rsp)
  sub    %r10d,%edi
  cltd
  mov    %r11d,0xc(%rsp)
  idiv   %edi
  lea    0x1(%rsi),%r8
  mov    $0xff,%esi
  mov    %r8,%rdx
  lea    (%rax,%rbx,1),%edi
  imul   %r14d,%edi
  add    %r11d,%edi
  movslq %edi,%rdi
  add    (%rsp),%rdi
  call   <memset@plt>
  mov    0x10(%rsp),%r10d
  mov    0xc(%rsp),%r11d
L79:
  add    $0x1,%r13d
  add    0x14(%rsp),%r12d
  add    %ebp,%r11d
  cmp    %r13d,%r15d
  jge    L48
  add    $0x28,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
  nopw   0x0(%rax,%rax,1)
L25:
  test   %ebp,%ebp
  jle    L142
  imul   %esi,%ebx
  movslq %ebp,%rdx
  mov    $0xff,%esi
  imul   %ebp,%r10d
  lea    (%rbx,%r10,1),%edi
  movslq %edi,%rdi
  add    (%rsp),%rdi
  add    $0x28,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  jmp    1050 <memset@plt>
L63:
  jne    L6
  test   %r8d,%r8d
  jle    L86
  lea    -0x1(%r8),%r12d
L112:
  mov    %r15d,%eax
  mov    %r10d,%r15d
  mov    %eax,%r10d
  jmp    L129
L97:
  mov    %r10d,%eax
  mov    %r12d,%ebx
  mov    %r9d,%r10d
  mov    %r8d,%r12d
  mov    %eax,%r15d
  jmp    L35
L6:
  mov    %r12d,%eax
  mov    %r10d,%r15d
  mov    %r8d,%r12d
  mov    %r9d,%r10d
  mov    %eax,%ebx
  jmp    L129
L86:
  lea    0x1(%r8),%eax
  cmp    %eax,%r8d
  jg     L142
  mov    %eax,%ebx
  jmp    L112
```

assistant: ```c
void drawline(unsigned char *buffer, int rowstride, int bpp, int x1, int y1, int x2, int y2) {
  int i, j;
  i = x1 - x2;
  j = y1 - y2;
  if (i == 0 && j == 0) {
    for (i = 0; i < bpp; i++)
      buffer[y1 * rowstride + x1 * bpp + i] = 0xff;
    return;
  }
  if (i < 0)
    i = -i;
  if (j < 0)
    j = -j;
  if (i < j) {
    if (y1 > y2) {
      i = y2;
      y2 = y1;
      y1 = i;
      i = x2;
      x2 = x1;
      x1 = i;
    }
    if (y2 == y1) {
      if (y2 > 0)
        y1--;
      else
        y2++;
    }
    for (j = y1; j <= y2; j++)
      for (i = 0; i < bpp; i++)
        buffer[j * rowstride + (x1 + (j - y1) * (x2 - x1) / (y2 - y1)) * bpp + i] = 0xff;
  } else {
    if (x1 > x2) {
      i = y2;
      y2 = y1;
      y1 = i;
      i = x2;
      x2 = x1;
      x1 = i;
    }
    for (i = x1; i <= x2; i++)
      for (j = 0; j < bpp; j++)
        buffer[(y1 + (i - x1) * (y2 - y1) / (x2 - x1)) * rowstride + i * bpp + j] = 0xff;
  }
}
```