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

```asm
<kernel_dgemv_n_8_vs_lib4>:
  endbr64
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  mov    0x28(%rsp),%r12
  mov    0x30(%rsp),%r13d
  test   %esi,%esi
  jle    L17
  shl    $0x2,%ecx
  mov    %edi,%ebx
  mov    %esi,%ebp
  mov    %rdx,%r10
  movslq %ecx,%rcx
  lea    (%rdx,%rcx,8),%r11
  cmp    $0x3,%esi
  jle    L116
  lea    -0x4(%rsi),%edi
  pxor   %xmm7,%xmm7
  pxor   %xmm8,%xmm8
  mov    %r11,%rdx
  shr    $0x2,%edi
  mov    %r8,%rcx
  mov    %r10,%rax
  xor    %esi,%esi
  movapd %xmm7,%xmm4
  movapd %xmm7,%xmm5
  movapd %xmm8,%xmm9
  add    $0x1,%edi
L28:
  movupd (%rax),%xmm15
  movupd (%rcx),%xmm3
  add    $0x1,%esi
  sub    $0xffffffffffffff80,%rdx
  movupd 0x20(%rax),%xmm14
  movlpd 0x8(%rax),%xmm14
  add    $0x20,%rcx
  sub    $0xffffffffffffff80,%rax
  movhpd -0x60(%rax),%xmm15
  movupd -0x10(%rcx),%xmm2
  movupd -0x40(%rax),%xmm13
  mulpd  %xmm3,%xmm15
  movupd -0x50(%rax),%xmm6
  movupd -0x20(%rax),%xmm12
  mulpd  %xmm3,%xmm14
  movlpd -0x68(%rax),%xmm6
  movupd -0x10(%rax),%xmm1
  movhpd -0x20(%rax),%xmm13
  movlpd -0x38(%rax),%xmm12
  mulpd  %xmm2,%xmm13
  movlpd -0x28(%rax),%xmm1
  movupd -0x70(%rax),%xmm11
  mulpd  %xmm3,%xmm6
  movupd -0x30(%rax),%xmm10
  mulpd  %xmm2,%xmm12
  mulpd  %xmm2,%xmm1
  movapd %xmm15,%xmm0
  movhpd -0x50(%rax),%xmm11
  unpcklpd %xmm14,%xmm0
  unpckhpd %xmm14,%xmm15
  movhpd -0x10(%rax),%xmm10
  addpd  %xmm5,%xmm0
  mulpd  %xmm3,%xmm11
  movapd %xmm13,%xmm5
  mulpd  %xmm2,%xmm10
  unpcklpd %xmm12,%xmm5
  unpckhpd %xmm12,%xmm13
  addpd  %xmm15,%xmm0
  addpd  %xmm5,%xmm0
  movapd %xmm0,%xmm5
  movapd %xmm11,%xmm0
  unpckhpd %xmm6,%xmm11
  unpcklpd %xmm6,%xmm0
  movupd -0x60(%rdx),%xmm6
  movlpd -0x78(%rdx),%xmm6
  addpd  %xmm13,%xmm5
  addpd  %xmm4,%xmm0
  movapd %xmm10,%xmm4
  unpckhpd %xmm1,%xmm10
  mulpd  %xmm3,%xmm6
  unpcklpd %xmm1,%xmm4
  addpd  %xmm11,%xmm0
  movupd -0x20(%rdx),%xmm11
  movlpd -0x38(%rdx),%xmm11
  mulpd  %xmm2,%xmm11
  addpd  %xmm4,%xmm0
  movapd %xmm0,%xmm4
  movupd -0x80(%rdx),%xmm0
  addpd  %xmm10,%xmm4
  movupd -0x40(%rdx),%xmm10
  movhpd -0x60(%rdx),%xmm0
  mulpd  %xmm3,%xmm0
  movhpd -0x20(%rdx),%xmm10
  mulpd  %xmm2,%xmm10
  movapd %xmm0,%xmm1
  unpckhpd %xmm6,%xmm0
  unpcklpd %xmm6,%xmm1
  movupd -0x30(%rdx),%xmm6
  addpd  %xmm7,%xmm1
  movhpd -0x10(%rdx),%xmm6
  mulpd  %xmm2,%xmm6
  addpd  %xmm0,%xmm1
  movapd %xmm10,%xmm0
  unpckhpd %xmm11,%xmm10
  unpcklpd %xmm11,%xmm0
  addpd  %xmm0,%xmm1
  movupd -0x70(%rdx),%xmm0
  movhpd -0x50(%rdx),%xmm0
  mulpd  %xmm3,%xmm0
  movapd %xmm1,%xmm7
  movupd -0x50(%rdx),%xmm1
  movlpd -0x68(%rdx),%xmm1
  addpd  %xmm10,%xmm7
  mulpd  %xmm3,%xmm1
  addsd  %xmm0,%xmm9
  unpckhpd %xmm0,%xmm0
  addsd  %xmm0,%xmm9
  movupd -0x10(%rdx),%xmm0
  movlpd -0x28(%rdx),%xmm0
  mulpd  %xmm2,%xmm0
  movapd %xmm1,%xmm2
  unpckhpd %xmm1,%xmm1
  addsd  %xmm8,%xmm2
  addsd  %xmm6,%xmm9
  unpckhpd %xmm6,%xmm6
  addsd  %xmm2,%xmm1
  addsd  %xmm6,%xmm9
  addsd  %xmm0,%xmm1
  unpckhpd %xmm0,%xmm0
  addsd  %xmm0,%xmm1
  movapd %xmm1,%xmm8
  cmp    %esi,%edi
  ja     L28
  mov    %edi,%eax
  shl    $0x2,%edi
  mov    %rax,%rdx
  shl    $0x5,%rax
  shl    $0x7,%rdx
  add    %rax,%r8
  add    %rdx,%r10
  add    %rdx,%r11
  cmp    %edi,%ebp
  jle    L74
L134:
  mov    %ebp,%edx
  mov    $0x1,%eax
  sub    %edi,%edx
  cmp    %ebp,%edi
  cmovl  %edx,%eax
  cmp    $0x1,%edx
  je     L80
  cmp    %ebp,%edi
  jge    L80
  movupd (%r10),%xmm3
  movupd 0x20(%r10),%xmm11
  mov    %eax,%edx
  movupd 0x10(%r10),%xmm0
  movlpd 0x8(%r10),%xmm0
  shr    %edx
  movhpd 0x10(%r10),%xmm3
  movupd (%r8),%xmm2
  movhpd 0x30(%r10),%xmm11
  movupd 0x30(%r10),%xmm1
  movapd %xmm3,%xmm6
  movlpd 0x28(%r10),%xmm1
  movapd %xmm0,%xmm10
  unpckhpd %xmm11,%xmm3
  mulpd  %xmm2,%xmm3
  unpcklpd %xmm11,%xmm6
  movupd 0x20(%r11),%xmm11
  mulpd  %xmm2,%xmm6
  unpcklpd %xmm1,%xmm10
  unpckhpd %xmm1,%xmm0
  mulpd  %xmm2,%xmm10
  movhpd 0x30(%r11),%xmm11
  mulpd  %xmm2,%xmm0
  movapd %xmm6,%xmm1
  unpcklpd %xmm10,%xmm1
  unpckhpd %xmm10,%xmm6
  addpd  %xmm5,%xmm1
  movapd %xmm1,%xmm5
  movapd %xmm3,%xmm1
  unpckhpd %xmm0,%xmm3
  unpcklpd %xmm0,%xmm1
  movupd 0x10(%r11),%xmm0
  movlpd 0x8(%r11),%xmm0
  addpd  %xmm6,%xmm5
  addpd  %xmm4,%xmm1
  movupd 0x30(%r11),%xmm6
  movlpd 0x28(%r11),%xmm6
  movapd %xmm0,%xmm10
  unpcklpd %xmm6,%xmm10
  unpckhpd %xmm6,%xmm0
  mulpd  %xmm2,%xmm10
  movapd %xmm1,%xmm4
  movupd (%r11),%xmm1
  addpd  %xmm3,%xmm4
  mulpd  %xmm2,%xmm0
  movhpd 0x10(%r11),%xmm1
  movapd %xmm1,%xmm3
  unpckhpd %xmm11,%xmm1
  mulpd  %xmm2,%xmm1
  unpcklpd %xmm11,%xmm3
  mulpd  %xmm2,%xmm3
  movapd %xmm3,%xmm12
  unpckhpd %xmm10,%xmm3
  unpcklpd %xmm10,%xmm12
  addpd  %xmm12,%xmm7
  addpd  %xmm3,%xmm7
  movapd %xmm1,%xmm3
  unpckhpd %xmm1,%xmm1
  addsd  %xmm9,%xmm3
  addsd  %xmm3,%xmm1
  movapd %xmm1,%xmm9
  movapd %xmm0,%xmm1
  unpckhpd %xmm0,%xmm0
  addsd  %xmm8,%xmm1
  addsd  %xmm1,%xmm0
  movapd %xmm0,%xmm8
  cmp    $0x1,%edx
  je     L54
  movupd 0x40(%r10),%xmm1
  movupd 0x60(%r10),%xmm11
  movupd 0x50(%r10),%xmm0
  movlpd 0x48(%r10),%xmm0
  movhpd 0x50(%r10),%xmm1
  movupd 0x10(%r8),%xmm2
  movhpd 0x70(%r10),%xmm11
  movupd 0x70(%r10),%xmm6
  movapd %xmm1,%xmm3
  movlpd 0x68(%r10),%xmm6
  movapd %xmm0,%xmm10
  unpckhpd %xmm11,%xmm1
  mulpd  %xmm2,%xmm1
  unpcklpd %xmm11,%xmm3
  movupd 0x60(%r11),%xmm11
  mulpd  %xmm2,%xmm3
  unpcklpd %xmm6,%xmm10
  unpckhpd %xmm6,%xmm0
  mulpd  %xmm2,%xmm10
  movhpd 0x70(%r11),%xmm11
  mulpd  %xmm2,%xmm0
  movapd %xmm3,%xmm6
  unpcklpd %xmm10,%xmm6
  unpckhpd %xmm10,%xmm3
  addpd  %xmm6,%xmm5
  movupd 0x70(%r11),%xmm6
  movlpd 0x68(%r11),%xmm6
  addpd  %xmm3,%xmm5
  movapd %xmm1,%xmm3
  unpckhpd %xmm0,%xmm1
  unpcklpd %xmm0,%xmm3
  movupd 0x50(%r11),%xmm0
  movlpd 0x48(%r11),%xmm0
  addpd  %xmm4,%xmm3
  movapd %xmm0,%xmm10
  unpckhpd %xmm6,%xmm0
  mulpd  %xmm2,%xmm0
  unpcklpd %xmm6,%xmm10
  mulpd  %xmm2,%xmm10
  movapd %xmm3,%xmm4
  addpd  %xmm1,%xmm4
  movupd 0x40(%r11),%xmm1
  movhpd 0x50(%r11),%xmm1
  movapd %xmm1,%xmm3
  unpckhpd %xmm11,%xmm1
  mulpd  %xmm2,%xmm1
  unpcklpd %xmm11,%xmm3
  mulpd  %xmm2,%xmm3
  movapd %xmm3,%xmm12
  unpckhpd %xmm10,%xmm3
  unpcklpd %xmm10,%xmm12
  addpd  %xmm12,%xmm7
  addpd  %xmm3,%xmm7
  movapd %xmm1,%xmm3
  unpckhpd %xmm1,%xmm1
  addsd  %xmm9,%xmm3
  addsd  %xmm3,%xmm1
  movapd %xmm1,%xmm9
  movapd %xmm0,%xmm1
  unpckhpd %xmm0,%xmm0
  addsd  %xmm8,%xmm1
  addsd  %xmm1,%xmm0
  movapd %xmm0,%xmm8
L54:
  mov    %eax,%edx
  and    $0xfffffffe,%edx
  mov    %edx,%esi
  mov    %rsi,%rcx
  lea    (%r8,%rsi,8),%r8
  shl    $0x5,%rcx
  add    %rcx,%r10
  add    %rcx,%r11
  cmp    %eax,%edx
  je     L74
L80:
  movsd  (%r8),%xmm0
  movupd (%r10),%xmm2
  movupd (%r11),%xmm3
  movapd %xmm0,%xmm1
  unpcklpd %xmm1,%xmm1
  mulpd  %xmm1,%xmm2
  addpd  %xmm2,%xmm5
  movupd 0x10(%r10),%xmm2
  mulpd  %xmm1,%xmm2
  mulpd  %xmm3,%xmm1
  addpd  %xmm2,%xmm4
  addpd  %xmm1,%xmm7
  movsd  0x10(%r11),%xmm1
  mulsd  %xmm0,%xmm1
  mulsd  0x18(%r11),%xmm0
  addsd  %xmm1,%xmm9
  addsd  %xmm0,%xmm8
L74:
  test   %r13d,%r13d
  je     L103
  movupd (%r9),%xmm3
  movupd 0x10(%r9),%xmm2
  movupd 0x20(%r9),%xmm6
  movsd  0x30(%r9),%xmm1
  movsd  0x38(%r9),%xmm0
  cmp    $0x1,%r13d
  je     L121
  subpd  %xmm7,%xmm6
  subpd  %xmm5,%xmm3
  subpd  %xmm4,%xmm2
  subsd  %xmm9,%xmm1
  subsd  %xmm8,%xmm0
  movapd %xmm6,%xmm7
  movapd %xmm3,%xmm5
  movapd %xmm2,%xmm4
  movapd %xmm1,%xmm9
  movapd %xmm0,%xmm8
L103:
  movapd %xmm7,%xmm3
  movups %xmm5,(%r12)
  unpckhpd %xmm3,%xmm3
  movups %xmm4,0x10(%r12)
  cmp    $0x7,%ebx
  jle    L86
  movups %xmm7,0x20(%r12)
  movsd  %xmm9,0x30(%r12)
  movsd  %xmm8,0x38(%r12)
L17:
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  ret
  nopl   0x0(%rax,%rax,1)
L86:
  movsd  %xmm7,0x20(%r12)
  cmp    $0x5,%ebx
  jle    L17
  movsd  %xmm3,0x28(%r12)
  cmp    $0x7,%ebx
  jne    L17
  movsd  %xmm9,0x30(%r12)
  jmp    L17
  nopl   0x0(%rax)
L121:
  addpd  %xmm6,%xmm7
  addpd  %xmm3,%xmm5
  addpd  %xmm2,%xmm4
  addsd  %xmm1,%xmm9
  addsd  %xmm0,%xmm8
  jmp    L103
  nopl   0x0(%rax,%rax,1)
L116:
  pxor   %xmm7,%xmm7
  pxor   %xmm8,%xmm8
  xor    %edi,%edi
  movapd %xmm7,%xmm4
  movapd %xmm7,%xmm5
  movapd %xmm8,%xmm9
  jmp    L134
```

assistant: ```c
void kernel_dgemv_n_8_vs_lib4(int km, int kmax, double *A0, int sda, double *x, double *y, double *z, 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;
  k = 0;
  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) {
    goto store;
  } 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];
    goto store;
  } else {
    y_0 = y[0] - y_0;
    y_1 = y[1] - y_1;
    y_2 = y[2] - y_2;
    y_3 = y[3] - y_3;
    y_4 = y[4] - y_4;
    y_5 = y[5] - y_5;
    y_6 = y[6] - y_6;
    y_7 = y[7] - y_7;
    goto store;
  }
store:
  z[0] = y_0;
  z[1] = y_1;
  z[2] = y_2;
  z[3] = y_3;
  if (km >= 8) {
    z[4] = y_4;
    z[5] = y_5;
    z[6] = y_6;
    z[7] = y_7;
  } else {
    z[4] = y_4;
    if (km >= 6) {
      z[5] = y_5;
      if (km > 6) {
        z[6] = y_6;
      }
    }
  }
}
```