user: 下面的汇编指令对应的C源代码是什么:

```asm
<kernel_dgemv_t_1_lib4>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  mov    %edi,-0x44(%rbp)
  mov    %rsi,-0x50(%rbp)
  mov    %edx,-0x48(%rbp)
  mov    %rcx,-0x58(%rbp)
  mov    %r8,-0x60(%rbp)
  mov    %r9,-0x68(%rbp)
  cmpl   $0x0,-0x44(%rbp)
  jle    L0
  movl   $0x4,-0x34(%rbp)
  movl   $0x4,-0x30(%rbp)
  mov    -0x44(%rbp),%eax
  mov    %eax,-0x2c(%rbp)
  pxor   %xmm0,%xmm0
  movsd  %xmm0,-0x28(%rbp)
  movl   $0x0,-0x38(%rbp)
  jmp    L4
L52:
  mov    -0x58(%rbp),%rax
  movsd  (%rax),%xmm0
  movsd  %xmm0,-0x20(%rbp)
  mov    -0x58(%rbp),%rax
  movsd  0x8(%rax),%xmm0
  movsd  %xmm0,-0x18(%rbp)
  mov    -0x58(%rbp),%rax
  movsd  0x10(%rax),%xmm0
  movsd  %xmm0,-0x10(%rbp)
  mov    -0x58(%rbp),%rax
  movsd  0x18(%rax),%xmm0
  movsd  %xmm0,-0x8(%rbp)
  mov    -0x50(%rbp),%rax
  movsd  (%rax),%xmm0
  mulsd  -0x20(%rbp),%xmm0
  movsd  -0x28(%rbp),%xmm1
  addsd  %xmm1,%xmm0
  movsd  %xmm0,-0x28(%rbp)
  mov    -0x50(%rbp),%rax
  add    $0x8,%rax
  movsd  (%rax),%xmm0
  mulsd  -0x18(%rbp),%xmm0
  movsd  -0x28(%rbp),%xmm1
  addsd  %xmm1,%xmm0
  movsd  %xmm0,-0x28(%rbp)
  mov    -0x50(%rbp),%rax
  add    $0x10,%rax
  movsd  (%rax),%xmm0
  mulsd  -0x10(%rbp),%xmm0
  movsd  -0x28(%rbp),%xmm1
  addsd  %xmm1,%xmm0
  movsd  %xmm0,-0x28(%rbp)
  mov    -0x50(%rbp),%rax
  add    $0x18,%rax
  movsd  (%rax),%xmm0
  mulsd  -0x8(%rbp),%xmm0
  movsd  -0x28(%rbp),%xmm1
  addsd  %xmm1,%xmm0
  movsd  %xmm0,-0x28(%rbp)
  mov    -0x48(%rbp),%eax
  imul   -0x30(%rbp),%eax
  cltq
  shl    $0x3,%rax
  add    %rax,-0x50(%rbp)
  addq   $0x20,-0x58(%rbp)
  mov    -0x30(%rbp),%eax
  add    %eax,-0x38(%rbp)
L4:
  mov    -0x2c(%rbp),%eax
  sub    -0x30(%rbp),%eax
  cmp    %eax,-0x38(%rbp)
  jle    L52
  jmp    L50
L49:
  mov    -0x58(%rbp),%rax
  movsd  (%rax),%xmm0
  movsd  %xmm0,-0x20(%rbp)
  mov    -0x50(%rbp),%rax
  movsd  (%rax),%xmm0
  mulsd  -0x20(%rbp),%xmm0
  movsd  -0x28(%rbp),%xmm1
  addsd  %xmm1,%xmm0
  movsd  %xmm0,-0x28(%rbp)
  addq   $0x8,-0x50(%rbp)
  addq   $0x8,-0x58(%rbp)
  addl   $0x1,-0x38(%rbp)
L50:
  mov    -0x38(%rbp),%eax
  cmp    -0x2c(%rbp),%eax
  jl     L49
  cmpl   $0x0,0x10(%rbp)
  jne    L5
  mov    -0x60(%rbp),%rax
  movsd  -0x28(%rbp),%xmm0
  movsd  %xmm0,(%rax)
  jmp    L19
L5:
  cmpl   $0x1,0x10(%rbp)
  jne    L29
  mov    -0x60(%rbp),%rax
  movsd  (%rax),%xmm0
  addsd  -0x28(%rbp),%xmm0
  mov    -0x68(%rbp),%rax
  movsd  %xmm0,(%rax)
  jmp    L19
L29:
  mov    -0x60(%rbp),%rax
  movsd  (%rax),%xmm0
  subsd  -0x28(%rbp),%xmm0
  mov    -0x68(%rbp),%rax
  movsd  %xmm0,(%rax)
  jmp    L19
L0:
  nop
L19:
  pop    %rbp
  ret
```

assistant: ```c
void kernel_dgemv_t_1_lib4(int kmax, double *A, int sda, double *x, double *y, double *z, int alg) {
  if (kmax <= 0)
    return;
  const int lda = 4;
  const int bs = 4;
  int k, ka = kmax;
  double x_0, x_1, x_2, x_3, y_0 = 0;
  k = 0;
  for (; k < ka - bs + 1; k += bs) {
    x_0 = x[0];
    x_1 = x[1];
    x_2 = x[2];
    x_3 = x[3];
    y_0 += A[0 + lda * 0] * x_0;
    y_0 += A[1 + lda * 0] * x_1;
    y_0 += A[2 + lda * 0] * x_2;
    y_0 += A[3 + lda * 0] * x_3;
    A += sda * bs;
    x += 4;
  }
  for (; k < ka; k++) {
    x_0 = x[0];
    y_0 += A[0 + lda * 0] * x_0;
    A += 1;
    x += 1;
  }
  if (alg == 0) {
    y[0] = y_0;
  } else if (alg == 1) {
    z[0] = y[0] + y_0;
  } else {
    z[0] = y[0] - y_0;
  }
}
```