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

```asm
<kernel_dtrmv_u_n_8_lib4>:
  endbr64
  test   %edi,%edi
  jle    L56
  push   %r12
  pxor   %xmm1,%xmm1
  shl    $0x2,%edx
  mov    %edi,%r11d
  push   %rbp
  movslq %edx,%rdx
  lea    0x100(%rsi),%r10
  lea    0x40(%rcx),%rbp
  push   %rbx
  movsd  0x10(%rcx),%xmm2
  lea    (%rsi,%rdx,8),%rdi
  mulsd  0x50(%rsi),%xmm2
  movsd  0x18(%rcx),%xmm0
  add    $0x100,%rdi
  movsd  0x70(%rsi),%xmm5
  movsd  0x20(%rcx),%xmm3
  movsd  0x90(%rsi),%xmm6
  movsd  0xb8(%rsi),%xmm7
  mulsd  %xmm0,%xmm5
  movupd 0x20(%rsi),%xmm11
  movsd  0x38(%rcx),%xmm8
  mulsd  %xmm3,%xmm6
  addsd  %xmm1,%xmm2
  mulsd  0x78(%rsi),%xmm0
  addsd  %xmm2,%xmm5
  movsd  0x30(%rcx),%xmm2
  movapd %xmm0,%xmm4
  movsd  0x28(%rcx),%xmm0
  addsd  %xmm5,%xmm6
  movsd  0x98(%rsi),%xmm5
  addsd  %xmm1,%xmm4
  mulsd  %xmm0,%xmm7
  mulsd  %xmm3,%xmm5
  mulsd  -0x80(%rdi),%xmm3
  addsd  %xmm5,%xmm4
  movsd  0xb0(%rsi),%xmm5
  addsd  %xmm1,%xmm3
  mulsd  %xmm0,%xmm5
  addsd  %xmm4,%xmm7
  movsd  -0x60(%rdi),%xmm4
  mulsd  %xmm0,%xmm4
  mulsd  -0x58(%rdi),%xmm0
  addsd  %xmm6,%xmm5
  movsd  0xd0(%rsi),%xmm6
  mulsd  %xmm2,%xmm6
  addsd  %xmm4,%xmm3
  movsd  -0x40(%rdi),%xmm4
  addsd  %xmm1,%xmm0
  mulsd  %xmm2,%xmm4
  addsd  %xmm5,%xmm6
  movsd  0xd8(%rsi),%xmm5
  mulsd  %xmm2,%xmm5
  addsd  %xmm3,%xmm4
  movsd  -0x38(%rdi),%xmm3
  mulsd  %xmm2,%xmm3
  mulsd  -0x30(%rdi),%xmm2
  addsd  %xmm7,%xmm5
  movupd (%rcx),%xmm7
  unpckhpd %xmm7,%xmm7
  addsd  %xmm0,%xmm3
  movsd  (%rsi),%xmm0
  mulsd  (%rcx),%xmm0
  mulpd  %xmm11,%xmm7
  movupd 0x40(%rsi),%xmm11
  addsd  %xmm1,%xmm2
  addsd  %xmm1,%xmm0
  movq   %xmm0,%xmm0
  addpd  %xmm7,%xmm0
  movupd 0x10(%rcx),%xmm7
  unpcklpd %xmm7,%xmm7
  mulpd  %xmm11,%xmm7
  movupd 0x60(%rsi),%xmm11
  addpd  %xmm7,%xmm0
  movupd 0x10(%rcx),%xmm7
  unpckhpd %xmm7,%xmm7
  mulpd  %xmm11,%xmm7
  addpd  %xmm7,%xmm0
  movupd 0x20(%rcx),%xmm7
  movupd 0x80(%rsi),%xmm11
  unpcklpd %xmm7,%xmm7
  mulpd  %xmm11,%xmm7
  movupd 0xa0(%rsi),%xmm11
  addpd  %xmm7,%xmm0
  movupd 0x20(%rcx),%xmm7
  unpckhpd %xmm7,%xmm7
  mulpd  %xmm11,%xmm7
  movupd 0xc0(%rsi),%xmm11
  addpd  %xmm7,%xmm0
  movupd 0x30(%rcx),%xmm7
  unpcklpd %xmm7,%xmm7
  mulpd  %xmm11,%xmm7
  movupd 0xe0(%rsi),%xmm11
  addpd  %xmm7,%xmm0
  movupd 0x30(%rcx),%xmm7
  unpckhpd %xmm7,%xmm7
  mulpd  %xmm11,%xmm7
  addpd  %xmm7,%xmm0
  movaps %xmm0,-0x30(%rsp)
  movsd  0xf0(%rsi),%xmm0
  mulsd  %xmm8,%xmm0
  addsd  %xmm6,%xmm0
  movapd %xmm0,%xmm13
  movsd  0xf8(%rsi),%xmm0
  mulsd  %xmm8,%xmm0
  addsd  %xmm5,%xmm0
  movapd %xmm0,%xmm12
  movsd  -0x20(%rdi),%xmm0
  mulsd  %xmm8,%xmm0
  addsd  %xmm4,%xmm0
  movapd %xmm0,%xmm15
  movsd  -0x18(%rdi),%xmm0
  mulsd  %xmm8,%xmm0
  movapd %xmm0,%xmm4
  movsd  -0x10(%rdi),%xmm0
  addsd  %xmm3,%xmm4
  mulsd  %xmm8,%xmm0
  mulsd  -0x8(%rdi),%xmm8
  addsd  %xmm2,%xmm0
  addsd  %xmm1,%xmm8
  movapd %xmm0,%xmm14
  movsd  %xmm8,-0x18(%rsp)
  cmp    $0xb,%r11d
  jle    L41
  lea    -0xc(%r11),%r12d
  mov    %rdi,%rdx
  mov    %rbp,%rcx
  mov    %r10,%rax
  shr    $0x2,%r12d
  xor    %esi,%esi
  lea    0x1(%r12),%ebx
  nopw   0x0(%rax,%rax,1)
L4:
  movupd (%rax),%xmm7
  movupd (%rcx),%xmm0
  add    $0x1,%esi
  sub    $0xffffffffffffff80,%rdx
  movupd 0x20(%rax),%xmm5
  movlpd 0x8(%rax),%xmm5
  add    $0x20,%rcx
  sub    $0xffffffffffffff80,%rax
  movhpd -0x60(%rax),%xmm7
  movupd -0x40(%rax),%xmm6
  movupd -0x10(%rcx),%xmm3
  mulpd  %xmm0,%xmm7
  movupd -0x20(%rax),%xmm2
  movlpd -0x38(%rax),%xmm2
  mulpd  %xmm0,%xmm5
  movhpd -0x20(%rax),%xmm6
  mulpd  %xmm3,%xmm6
  mulpd  %xmm3,%xmm2
  movapd %xmm7,%xmm1
  unpcklpd %xmm5,%xmm1
  addpd  -0x30(%rsp),%xmm1
  unpckhpd %xmm5,%xmm7
  movapd %xmm6,%xmm5
  unpcklpd %xmm2,%xmm5
  unpckhpd %xmm2,%xmm6
  addpd  %xmm7,%xmm1
  movupd -0x30(%rax),%xmm7
  movhpd -0x10(%rax),%xmm7
  addpd  %xmm5,%xmm1
  mulpd  %xmm3,%xmm7
  addpd  %xmm6,%xmm1
  movupd -0x40(%rdx),%xmm6
  movhpd -0x20(%rdx),%xmm6
  movaps %xmm1,-0x30(%rsp)
  movupd -0x70(%rax),%xmm1
  mulpd  %xmm3,%xmm6
  movhpd -0x50(%rax),%xmm1
  mulpd  %xmm0,%xmm1
  movlpd %xmm6,-0x10(%rsp)
  unpckhpd %xmm6,%xmm6
  movapd %xmm1,%xmm2
  unpckhpd %xmm1,%xmm1
  addsd  %xmm13,%xmm2
  addsd  %xmm1,%xmm2
  movupd -0x50(%rax),%xmm1
  movlpd -0x68(%rax),%xmm1
  mulpd  %xmm0,%xmm1
  movapd %xmm2,%xmm13
  movupd -0x10(%rax),%xmm2
  movlpd -0x28(%rax),%xmm2
  addsd  %xmm7,%xmm13
  unpckhpd %xmm7,%xmm7
  mulpd  %xmm3,%xmm2
  movapd %xmm1,%xmm5
  unpckhpd %xmm1,%xmm1
  addsd  %xmm7,%xmm13
  addsd  %xmm12,%xmm5
  movlpd %xmm2,-0x8(%rsp)
  unpckhpd %xmm2,%xmm2
  addsd  %xmm1,%xmm5
  movupd -0x80(%rdx),%xmm1
  movhpd -0x60(%rdx),%xmm1
  mulpd  %xmm0,%xmm1
  movapd %xmm5,%xmm12
  movapd %xmm1,%xmm5
  unpckhpd %xmm1,%xmm1
  addsd  %xmm15,%xmm5
  addsd  %xmm1,%xmm5
  movupd -0x20(%rdx),%xmm1
  movlpd -0x38(%rdx),%xmm1
  mulpd  %xmm3,%xmm1
  movapd %xmm5,%xmm15
  movupd -0x60(%rdx),%xmm5
  movlpd -0x78(%rdx),%xmm5
  mulpd  %xmm0,%xmm5
  movapd %xmm5,%xmm8
  unpckhpd %xmm5,%xmm5
  addsd  %xmm4,%xmm8
  movapd %xmm8,%xmm4
  movupd -0x70(%rdx),%xmm8
  addsd  %xmm5,%xmm4
  movhpd -0x50(%rdx),%xmm8
  movupd -0x30(%rdx),%xmm5
  addsd  -0x8(%rsp),%xmm12
  mulpd  %xmm0,%xmm8
  addsd  -0x10(%rsp),%xmm15
  movhpd -0x10(%rdx),%xmm5
  addsd  %xmm1,%xmm4
  unpckhpd %xmm1,%xmm1
  mulpd  %xmm3,%xmm5
  addsd  %xmm2,%xmm12
  addsd  %xmm6,%xmm15
  addsd  %xmm1,%xmm4
  movapd %xmm8,%xmm9
  unpckhpd %xmm8,%xmm8
  addsd  %xmm14,%xmm9
  addsd  %xmm8,%xmm9
  movupd -0x50(%rdx),%xmm8
  movlpd -0x68(%rdx),%xmm8
  mulpd  %xmm0,%xmm8
  movupd -0x10(%rdx),%xmm0
  movlpd -0x28(%rdx),%xmm0
  movapd %xmm9,%xmm14
  mulpd  %xmm3,%xmm0
  movsd  -0x18(%rsp),%xmm3
  addsd  %xmm5,%xmm14
  unpckhpd %xmm5,%xmm5
  addsd  %xmm8,%xmm3
  unpckhpd %xmm8,%xmm8
  addsd  %xmm5,%xmm14
  addsd  %xmm8,%xmm3
  addsd  %xmm0,%xmm3
  unpckhpd %xmm0,%xmm0
  addsd  %xmm0,%xmm3
  movsd  %xmm3,-0x18(%rsp)
  cmp    %esi,%ebx
  ja     L4
  mov    %rbx,%rax
  shl    $0x5,%rbx
  shl    $0x7,%rax
  add    %rbx,%rbp
  add    %rax,%r10
  add    %rax,%rdi
  lea    0xc(,%r12,4),%eax
L22:
  cmp    %eax,%r11d
  jle    L0
  sub    %eax,%r11d
  cmp    $0x1,%r11d
  je     L91
  movupd (%r10),%xmm1
  movupd 0x20(%r10),%xmm7
  mov    %r11d,%eax
  movupd 0x10(%r10),%xmm0
  movlpd 0x8(%r10),%xmm0
  shr    %eax
  movhpd 0x10(%r10),%xmm1
  movupd 0x0(%rbp),%xmm2
  movhpd 0x30(%r10),%xmm7
  movupd 0x30(%r10),%xmm5
  movapd %xmm1,%xmm3
  movlpd 0x28(%r10),%xmm5
  movapd %xmm0,%xmm6
  unpckhpd %xmm7,%xmm1
  mulpd  %xmm2,%xmm1
  unpcklpd %xmm7,%xmm3
  mulpd  %xmm2,%xmm3
  unpcklpd %xmm5,%xmm6
  unpckhpd %xmm5,%xmm0
  movupd 0x30(%rdi),%xmm5
  mulpd  %xmm2,%xmm6
  movlpd 0x28(%rdi),%xmm5
  mulpd  %xmm2,%xmm0
  movapd %xmm3,%xmm8
  unpcklpd %xmm6,%xmm8
  addpd  -0x30(%rsp),%xmm8
  unpckhpd %xmm6,%xmm3
  movupd 0x20(%rdi),%xmm6
  movhpd 0x30(%rdi),%xmm6
  movapd %xmm8,%xmm11
  addpd  %xmm3,%xmm11
  movapd %xmm1,%xmm3
  unpckhpd %xmm1,%xmm1
  addsd  %xmm13,%xmm3
  movaps %xmm11,-0x30(%rsp)
  addsd  %xmm3,%xmm1
  movapd %xmm1,%xmm13
  movapd %xmm0,%xmm1
  unpckhpd %xmm0,%xmm0
  addsd  %xmm12,%xmm1
  addsd  %xmm1,%xmm0
  movupd (%rdi),%xmm1
  movhpd 0x10(%rdi),%xmm1
  movapd %xmm1,%xmm3
  movapd %xmm0,%xmm12
  movupd 0x10(%rdi),%xmm0
  movlpd 0x8(%rdi),%xmm0
  unpcklpd %xmm6,%xmm3
  unpckhpd %xmm6,%xmm1
  mulpd  %xmm2,%xmm3
  mulpd  %xmm2,%xmm1
  movapd %xmm3,%xmm7
  unpckhpd %xmm3,%xmm3
  addsd  %xmm15,%xmm7
  addsd  %xmm7,%xmm3
  movapd %xmm3,%xmm15
  movapd %xmm0,%xmm3
  unpckhpd %xmm5,%xmm0
  mulpd  %xmm2,%xmm0
  unpcklpd %xmm5,%xmm3
  mulpd  %xmm2,%xmm3
  addsd  %xmm3,%xmm4
  unpckhpd %xmm3,%xmm3
  addsd  %xmm3,%xmm4
  movapd %xmm1,%xmm3
  unpckhpd %xmm1,%xmm1
  addsd  %xmm14,%xmm3
  addsd  %xmm3,%xmm1
  movapd %xmm1,%xmm14
  movsd  -0x18(%rsp),%xmm1
  addsd  %xmm0,%xmm1
  unpckhpd %xmm0,%xmm0
  addsd  %xmm1,%xmm0
  movapd %xmm0,%xmm10
  movsd  %xmm0,-0x18(%rsp)
  cmp    $0x1,%eax
  je     L84
  movupd 0x40(%r10),%xmm1
  movupd 0x60(%r10),%xmm7
  movupd 0x50(%r10),%xmm0
  movlpd 0x48(%r10),%xmm0
  movhpd 0x50(%r10),%xmm1
  movupd 0x10(%rbp),%xmm2
  movhpd 0x70(%r10),%xmm7
  movupd 0x70(%r10),%xmm5
  movapd %xmm1,%xmm3
  movlpd 0x68(%r10),%xmm5
  movapd %xmm0,%xmm6
  unpckhpd %xmm7,%xmm1
  mulpd  %xmm2,%xmm1
  unpcklpd %xmm7,%xmm3
  mulpd  %xmm2,%xmm3
  unpcklpd %xmm5,%xmm6
  unpckhpd %xmm5,%xmm0
  movupd 0x70(%rdi),%xmm5
  mulpd  %xmm2,%xmm6
  movlpd 0x68(%rdi),%xmm5
  mulpd  %xmm2,%xmm0
  movapd %xmm3,%xmm8
  unpcklpd %xmm6,%xmm8
  unpckhpd %xmm6,%xmm3
  movupd 0x60(%rdi),%xmm6
  addpd  %xmm11,%xmm8
  movhpd 0x70(%rdi),%xmm6
  addpd  %xmm3,%xmm8
  movapd %xmm1,%xmm3
  unpckhpd %xmm1,%xmm1
  addsd  %xmm13,%xmm3
  movaps %xmm8,-0x30(%rsp)
  addsd  %xmm3,%xmm1
  movapd %xmm1,%xmm13
  movapd %xmm0,%xmm1
  unpckhpd %xmm0,%xmm0
  addsd  %xmm12,%xmm1
  addsd  %xmm1,%xmm0
  movupd 0x40(%rdi),%xmm1
  movhpd 0x50(%rdi),%xmm1
  movapd %xmm1,%xmm3
  movapd %xmm0,%xmm12
  movupd 0x50(%rdi),%xmm0
  movlpd 0x48(%rdi),%xmm0
  unpcklpd %xmm6,%xmm3
  unpckhpd %xmm6,%xmm1
  mulpd  %xmm2,%xmm3
  mulpd  %xmm2,%xmm1
  movapd %xmm3,%xmm7
  unpckhpd %xmm3,%xmm3
  addsd  %xmm15,%xmm7
  addsd  %xmm7,%xmm3
  movapd %xmm3,%xmm15
  movapd %xmm0,%xmm3
  unpckhpd %xmm5,%xmm0
  mulpd  %xmm2,%xmm0
  unpcklpd %xmm5,%xmm3
  mulpd  %xmm2,%xmm3
  addsd  %xmm3,%xmm4
  unpckhpd %xmm3,%xmm3
  addsd  %xmm3,%xmm4
  movapd %xmm1,%xmm3
  unpckhpd %xmm1,%xmm1
  addsd  %xmm14,%xmm3
  addsd  %xmm3,%xmm1
  movapd %xmm1,%xmm14
  movapd %xmm0,%xmm1
  unpckhpd %xmm0,%xmm0
  addsd  %xmm10,%xmm1
  addsd  %xmm1,%xmm0
  movsd  %xmm0,-0x18(%rsp)
L84:
  mov    %r11d,%eax
  and    $0xfffffffe,%eax
  mov    %eax,%ecx
  mov    %rcx,%rdx
  lea    0x0(%rbp,%rcx,8),%rbp
  shl    $0x5,%rdx
  add    %rdx,%r10
  add    %rdx,%rdi
  cmp    %r11d,%eax
  je     L0
L91:
  movsd  0x0(%rbp),%xmm0
  movupd (%r10),%xmm6
  movapd %xmm0,%xmm1
  unpcklpd %xmm1,%xmm1
  mulpd  %xmm6,%xmm1
  addpd  -0x30(%rsp),%xmm1
  movaps %xmm1,-0x30(%rsp)
  movsd  0x10(%r10),%xmm1
  mulsd  %xmm0,%xmm1
  addsd  %xmm1,%xmm13
  movsd  0x18(%r10),%xmm1
  mulsd  %xmm0,%xmm1
  addsd  %xmm1,%xmm12
  movsd  (%rdi),%xmm1
  mulsd  %xmm0,%xmm1
  addsd  %xmm1,%xmm15
  movsd  0x8(%rdi),%xmm1
  mulsd  %xmm0,%xmm1
  addsd  %xmm1,%xmm4
  movsd  0x10(%rdi),%xmm1
  mulsd  %xmm0,%xmm1
  mulsd  0x18(%rdi),%xmm0
  addsd  -0x18(%rsp),%xmm0
  addsd  %xmm1,%xmm14
  movsd  %xmm0,-0x18(%rsp)
L0:
  movapd -0x30(%rsp),%xmm6
  movapd %xmm6,%xmm3
  movapd %xmm6,%xmm2
  unpckhpd %xmm3,%xmm3
  movapd %xmm3,%xmm1
  test   %r9d,%r9d
  je     L48
  movupd (%r8),%xmm0
  movsd  0x10(%r8),%xmm7
  movsd  0x20(%r8),%xmm5
  movsd  0x28(%r8),%xmm10
  movapd %xmm0,%xmm6
  movsd  0x30(%r8),%xmm11
  movsd  0x38(%r8),%xmm3
  unpckhpd %xmm6,%xmm6
  movapd %xmm6,%xmm8
  movsd  0x18(%r8),%xmm6
  cmp    $0x1,%r9d
  je     L63
  subpd  -0x30(%rsp),%xmm0
  subsd  -0x18(%rsp),%xmm3
  subsd  %xmm13,%xmm7
  subsd  %xmm12,%xmm6
  pop    %rbx
  pop    %rbp
  subsd  %xmm15,%xmm5
  subsd  %xmm4,%xmm10
  pop    %r12
  subsd  %xmm14,%xmm11
  movups %xmm0,(%r8)
  movsd  %xmm7,0x10(%r8)
  movsd  %xmm6,0x18(%r8)
  movsd  %xmm5,0x20(%r8)
  movsd  %xmm10,0x28(%r8)
  movsd  %xmm11,0x30(%r8)
  movsd  %xmm3,0x38(%r8)
  ret
L48:
  movsd  %xmm4,0x28(%r8)
  movsd  -0x18(%rsp),%xmm4
  pop    %rbx
  movsd  %xmm6,(%r8)
  pop    %rbp
  pop    %r12
  movsd  %xmm3,0x8(%r8)
  movsd  %xmm13,0x10(%r8)
  movsd  %xmm12,0x18(%r8)
  movsd  %xmm15,0x20(%r8)
  movsd  %xmm14,0x30(%r8)
  movsd  %xmm4,0x38(%r8)
  ret
  nopw   0x0(%rax,%rax,1)
L56:
  ret
  nopl   0x0(%rax)
L63:
  addsd  -0x18(%rsp),%xmm3
  addsd  %xmm0,%xmm2
  pop    %rbx
  addsd  %xmm8,%xmm1
  addsd  %xmm13,%xmm7
  pop    %rbp
  pop    %r12
  addsd  %xmm12,%xmm6
  addsd  %xmm15,%xmm5
  addsd  %xmm10,%xmm4
  addsd  %xmm14,%xmm11
  movsd  %xmm2,(%r8)
  movsd  %xmm1,0x8(%r8)
  movsd  %xmm7,0x10(%r8)
  movsd  %xmm6,0x18(%r8)
  movsd  %xmm5,0x20(%r8)
  movsd  %xmm4,0x28(%r8)
  movsd  %xmm11,0x30(%r8)
  movsd  %xmm3,0x38(%r8)
  ret
  nopl   0x0(%rax)
L41:
  mov    $0x8,%eax
  jmp    L22
```

assistant: ```c
void kernel_dtrmv_u_n_8_lib4(int kmax, double *A0, int sda, double *x, double *y, int alg) {
  if (kmax <= 0)
    return;
  double *A1 = A0 + 4 * sda;
  const int lda = 4;
  int k;
  double x_0, x_1, x_2, x_3, y_0 = 0, y_1 = 0, y_2 = 0, y_3 = 0, y_4 = 0, y_5 = 0, y_6 = 0, y_7 = 0;
  x_0 = x[0];
  x_1 = x[1];
  x_2 = x[2];
  x_3 = x[3];
  y_0 += A0[0 + lda * 0] * x_0;
  y_0 += A0[0 + lda * 1] * x_1;
  y_1 += A0[1 + lda * 1] * x_1;
  y_0 += A0[0 + lda * 2] * x_2;
  y_1 += A0[1 + lda * 2] * x_2;
  y_2 += A0[2 + lda * 2] * x_2;
  y_0 += A0[0 + lda * 3] * x_3;
  y_1 += A0[1 + lda * 3] * x_3;
  y_2 += A0[2 + lda * 3] * x_3;
  y_3 += A0[3 + lda * 3] * x_3;
  A0 += 4 * lda;
  A1 += 4 * lda;
  x += 4;
  x_0 = x[0];
  x_1 = x[1];
  x_2 = x[2];
  x_3 = x[3];
  y_0 += A0[0 + lda * 0] * x_0;
  y_1 += A0[1 + lda * 0] * x_0;
  y_2 += A0[2 + lda * 0] * x_0;
  y_3 += A0[3 + lda * 0] * x_0;
  y_4 += A1[0 + lda * 0] * x_0;
  y_0 += A0[0 + lda * 1] * x_1;
  y_1 += A0[1 + lda * 1] * x_1;
  y_2 += A0[2 + lda * 1] * x_1;
  y_3 += A0[3 + lda * 1] * x_1;
  y_4 += A1[0 + lda * 1] * x_1;
  y_5 += A1[1 + lda * 1] * x_1;
  y_0 += A0[0 + lda * 2] * x_2;
  y_1 += A0[1 + lda * 2] * x_2;
  y_2 += A0[2 + lda * 2] * x_2;
  y_3 += A0[3 + lda * 2] * x_2;
  y_4 += A1[0 + lda * 2] * x_2;
  y_5 += A1[1 + lda * 2] * x_2;
  y_6 += A1[2 + lda * 2] * x_2;
  y_0 += A0[0 + lda * 3] * x_3;
  y_1 += A0[1 + lda * 3] * x_3;
  y_2 += A0[2 + lda * 3] * x_3;
  y_3 += A0[3 + lda * 3] * x_3;
  y_4 += A1[0 + lda * 3] * x_3;
  y_5 += A1[1 + lda * 3] * x_3;
  y_6 += A1[2 + lda * 3] * x_3;
  y_7 += A1[3 + lda * 3] * x_3;
  A0 += 4 * lda;
  A1 += 4 * lda;
  x += 4;
  k = 8;
  for (; k < kmax - 3; k += 4) {
    x_0 = x[0];
    x_1 = x[1];
    x_2 = x[2];
    x_3 = x[3];
    y_0 += A0[0 + lda * 0] * x_0;
    y_1 += A0[1 + lda * 0] * x_0;
    y_2 += A0[2 + lda * 0] * x_0;
    y_3 += A0[3 + lda * 0] * x_0;
    y_4 += A1[0 + lda * 0] * x_0;
    y_5 += A1[1 + lda * 0] * x_0;
    y_6 += A1[2 + lda * 0] * x_0;
    y_7 += A1[3 + lda * 0] * x_0;
    y_0 += A0[0 + lda * 1] * x_1;
    y_1 += A0[1 + lda * 1] * x_1;
    y_2 += A0[2 + lda * 1] * x_1;
    y_3 += A0[3 + lda * 1] * x_1;
    y_4 += A1[0 + lda * 1] * x_1;
    y_5 += A1[1 + lda * 1] * x_1;
    y_6 += A1[2 + lda * 1] * x_1;
    y_7 += A1[3 + lda * 1] * x_1;
    y_0 += A0[0 + lda * 2] * x_2;
    y_1 += A0[1 + lda * 2] * x_2;
    y_2 += A0[2 + lda * 2] * x_2;
    y_3 += A0[3 + lda * 2] * x_2;
    y_4 += A1[0 + lda * 2] * x_2;
    y_5 += A1[1 + lda * 2] * x_2;
    y_6 += A1[2 + lda * 2] * x_2;
    y_7 += A1[3 + lda * 2] * x_2;
    y_0 += A0[0 + lda * 3] * x_3;
    y_1 += A0[1 + lda * 3] * x_3;
    y_2 += A0[2 + lda * 3] * x_3;
    y_3 += A0[3 + lda * 3] * x_3;
    y_4 += A1[0 + lda * 3] * x_3;
    y_5 += A1[1 + lda * 3] * x_3;
    y_6 += A1[2 + lda * 3] * x_3;
    y_7 += A1[3 + lda * 3] * x_3;
    A0 += 4 * lda;
    A1 += 4 * lda;
    x += 4;
  }
  for (; k < kmax; k++) {
    x_0 = x[0];
    y_0 += A0[0 + lda * 0] * x_0;
    y_1 += A0[1 + lda * 0] * x_0;
    y_2 += A0[2 + lda * 0] * x_0;
    y_3 += A0[3 + lda * 0] * x_0;
    y_4 += A1[0 + lda * 0] * x_0;
    y_5 += A1[1 + lda * 0] * x_0;
    y_6 += A1[2 + lda * 0] * x_0;
    y_7 += A1[3 + lda * 0] * x_0;
    A0 += 1 * lda;
    A1 += 1 * lda;
    x += 1;
  }
  if (alg == 0) {
    y[0] = y_0;
    y[1] = y_1;
    y[2] = y_2;
    y[3] = y_3;
    y[4] = y_4;
    y[5] = y_5;
    y[6] = y_6;
    y[7] = y_7;
  } else if (alg == 1) {
    y[0] += y_0;
    y[1] += y_1;
    y[2] += y_2;
    y[3] += y_3;
    y[4] += y_4;
    y[5] += y_5;
    y[6] += y_6;
    y[7] += y_7;
  } else {
    y[0] -= y_0;
    y[1] -= y_1;
    y[2] -= y_2;
    y[3] -= y_3;
    y[4] -= y_4;
    y[5] -= y_5;
    y[6] -= y_6;
    y[7] -= y_7;
  }
}
```