user: 提供的汇编代码用C语言表示会是什么样子:

```asm
<forward_gradient>:
  endbr64
  push   %r15
  mov    %ecx,%r10d
  lea    -0x1(%r8),%ecx
  mov    %rsi,%r9
  push   %r14
  lea    -0x1(%r10),%eax
  mov    %rdx,%rsi
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  mov    %r8d,-0x1c(%rsp)
  mov    %ecx,-0x44(%rsp)
  mov    %eax,-0x38(%rsp)
  test   %ecx,%ecx
  jle    L142
  mov    %eax,%ebx
  test   %eax,%eax
  jle    L388
  shr    $0x2,%eax
  and    $0xfffffffc,%ebx
  lea    -0x2(%r10),%r15d
  mov    %r10d,%r14d
  sub    $0x1,%eax
  sub    %ebx,%r14d
  movslq %r10d,%rcx
  mov    %ebx,-0x28(%rsp)
  add    $0x1,%rax
  lea    -0x1(%r14),%ebx
  mov    %r15d,-0x34(%rsp)
  xor    %ebp,%ebp
  shl    $0x4,%rax
  mov    %r14d,-0x24(%rsp)
  lea    0x0(,%rcx,4),%r12
  mov    %rax,-0x30(%rsp)
  mov    %r15d,%eax
  lea    (%rdi,%r12,1),%rdx
  lea    0x4(,%rax,4),%rax
  mov    %ebx,-0x20(%rsp)
  mov    %rdx,%r8
  movq   $0x0,-0x58(%rsp)
  movq   $0x0,-0x50(%rsp)
  movl   $0x0,-0x48(%rsp)
  mov    %rax,-0x10(%rsp)
  mov    %rcx,-0x40(%rsp)
  mov    %r9,%rcx
  mov    %rdx,-0x18(%rsp)
  mov    %rdi,%rdx
  nopw   0x0(%rax,%rax,1)
L198:
  mov    -0x58(%rsp),%rax
  mov    -0x40(%rsp),%rbx
  lea    0x10(%rcx),%r11
  lea    0x4(%rdx),%r14
  mov    %rax,%r13
  add    %rbx,%rax
  lea    0x10(%r8),%rbx
  mov    %rax,-0x58(%rsp)
  mov    -0x50(%rsp),%rax
  add    %rsi,%rax
  cmp    %rbx,%rcx
  setae  %r15b
  cmp    %r11,%r8
  setae  %bl
  or     %ebx,%r15d
  lea    0x14(%rdx),%rbx
  cmp    %rbx,%rcx
  setae  %bl
  cmp    %rdx,%r11
  setbe  %r11b
  or     %ebx,%r11d
  and    %r15d,%r11d
  cmp    $0x2,%r10d
  lea    0x4(%r8),%r15
  setne  %bl
  and    %ebx,%r11d
  mov    %rax,%rbx
  sub    %r15,%rbx
  lea    0x4(%rcx),%r15
  cmp    $0x8,%rbx
  seta   %bl
  and    %ebx,%r11d
  mov    %rax,%rbx
  sub    %r15,%rbx
  cmp    $0x8,%rbx
  seta   %bl
  test   %bl,%r11b
  je     L57
  mov    %rax,%r11
  sub    %r14,%r11
  cmp    $0xc,%r11
  jbe    L57
  cmpl   $0x2,-0x34(%rsp)
  jbe    L200
  mov    -0x30(%rsp),%rbx
  xor    %r11d,%r11d
  nopl   0x0(%rax,%rax,1)
L150:
  movups (%r14,%r11,1),%xmm0
  movups (%rdx,%r11,1),%xmm2
  subps  %xmm2,%xmm0
  movups %xmm0,(%rcx,%r11,1)
  movups (%r8,%r11,1),%xmm0
  movups (%rdx,%r11,1),%xmm3
  subps  %xmm3,%xmm0
  movups %xmm0,(%rax,%r11,1)
  add    $0x10,%r11
  cmp    %rbx,%r11
  jne    L150
  mov    -0x28(%rsp),%eax
  cmp    %eax,-0x38(%rsp)
  je     L104
  cmpl   $0x2,-0x24(%rsp)
  mov    -0x20(%rsp),%r14d
  je     L289
  mov    %eax,%r11d
L110:
  lea    0x1(%r13,%r11,1),%r15
  add    -0x58(%rsp),%r11
  lea    0x0(,%r15,4),%rbx
  movq   (%rdi,%r15,4),%xmm0
  lea    -0x4(%rdi,%rbx,1),%r13
  movq   0x0(%r13),%xmm1
  subps  %xmm1,%xmm0
  movlps %xmm0,-0x4(%r9,%rbx,1)
  movq   (%rdi,%r11,4),%xmm0
  mov    %r14d,%r11d
  movq   0x0(%r13),%xmm1
  and    $0xfffffffe,%r11d
  subps  %xmm1,%xmm0
  add    %r11d,%eax
  movlps %xmm0,-0x4(%rsi,%rbx,1)
  cmp    %r11d,%r14d
  je     L104
L289:
  add    %ebp,%eax
  movslq %eax,%r11
  lea    0x1(%rax),%ebx
  add    %r10d,%eax
  lea    (%rdi,%r11,4),%r13
  movslq %ebx,%rbx
  cltq
  movss  (%rdi,%rbx,4),%xmm0
  subss  0x0(%r13),%xmm0
  movss  %xmm0,(%r9,%r11,4)
  movss  (%rdi,%rax,4),%xmm0
  subss  0x0(%r13),%xmm0
  movss  %xmm0,(%rsi,%r11,4)
L104:
  addl   $0x1,-0x48(%rsp)
  add    %r12,%rcx
  mov    -0x48(%rsp),%eax
  add    %r12,%r8
  add    %r12,-0x50(%rsp)
  add    %r12,%rdx
  add    %r10d,%ebp
  cmp    -0x44(%rsp),%eax
  jne    L198
L258:
  mov    -0x44(%rsp),%ebx
  imul   %r10d,%ebx
  movslq %ebx,%r12
  lea    0x0(,%r12,4),%rax
  lea    0x4(%rax),%rdx
  lea    (%rsi,%rax,1),%rcx
  lea    (%r9,%rdx,1),%r13
  mov    %rcx,%rbp
  lea    (%r9,%rax,1),%r11
  sub    %r13,%rbp
  lea    (%rdi,%rdx,1),%r8
  cmp    $0x8,%rbp
  mov    %r11,%rbp
  seta   %r13b
  sub    %r8,%rbp
  cmp    $0xc,%rbp
  seta   %bpl
  and    %r13d,%ebp
  cmp    $0x2,%r10d
  setne  %r13b
  test   %r13b,%bpl
  je     L69
  mov    %rcx,%rbp
  sub    %r8,%rbp
  cmp    $0xc,%rbp
  jbe    L69
  cmpl   $0x2,-0x34(%rsp)
  jbe    L173
  mov    -0x38(%rsp),%ebp
  add    %rdi,%rax
  xor    %edx,%edx
  pxor   %xmm1,%xmm1
  shr    $0x2,%ebp
  shl    $0x4,%rbp
  nopl   0x0(%rax)
L226:
  movups (%r8,%rdx,1),%xmm0
  movups (%rax,%rdx,1),%xmm4
  subps  %xmm4,%xmm0
  movups %xmm0,(%r11,%rdx,1)
  movups %xmm1,(%rcx,%rdx,1)
  add    $0x10,%rdx
  cmp    %rbp,%rdx
  jne    L226
  mov    -0x38(%rsp),%ecx
  mov    %ecx,%edx
  and    $0xfffffffc,%edx
  mov    %edx,%eax
  cmp    %edx,%ecx
  je     L388
  mov    %r10d,%r8d
  sub    %edx,%r8d
  lea    -0x1(%r8),%ecx
  cmp    $0x2,%r8d
  je     L30
L346:
  lea    0x1(%r12,%rdx,1),%r8
  lea    0x0(,%r8,4),%rdx
  movq   (%rdi,%r8,4),%xmm0
  movq   -0x4(%rdi,%rdx,1),%xmm1
  subps  %xmm1,%xmm0
  movlps %xmm0,-0x4(%r9,%rdx,1)
  movq   $0x0,-0x4(%rsi,%rdx,1)
  mov    %ecx,%edx
  and    $0xfffffffe,%edx
  add    %edx,%eax
  cmp    %ecx,%edx
  je     L388
L30:
  add    %ebx,%eax
  cltq
  add    $0x1,%rax
  movss  (%rdi,%rax,4),%xmm0
  subss  -0x4(%rdi,%rax,4),%xmm0
  lea    0x0(,%rax,4),%rdx
  movss  %xmm0,-0x4(%r9,%rdx,1)
  movl   $0x0,-0x4(%rsi,%rdx,1)
L388:
  cmpl   $0x1,-0x1c(%rsp)
  jle    L164
  cmp    $0x1,%r10d
  jne    L158
  lea    0x14(%rdi),%rax
  lea    0x10(%r9),%rdx
  mov    -0x1c(%rsp),%ebx
  cmp    %rax,%r9
  lea    0x4(%rdi),%rcx
  setae  %al
  cmp    %rdx,%rdi
  setae  %dl
  or     %edx,%eax
  cmp    $0x2,%ebx
  setne  %dl
  and    %edx,%eax
  mov    %rsi,%rdx
  sub    %rcx,%rdx
  cmp    $0xc,%rdx
  seta   %dl
  test   %dl,%al
  je     L294
  lea    0x4(%r9),%rdx
  mov    %rsi,%rax
  sub    %rdx,%rax
  cmp    $0x8,%rax
  jbe    L294
  lea    -0x2(%rbx),%eax
  cmp    $0x2,%eax
  jbe    L3
  mov    -0x44(%rsp),%edx
  xor    %eax,%eax
  pxor   %xmm1,%xmm1
  shr    $0x2,%edx
  shl    $0x4,%rdx
  cs nopw 0x0(%rax,%rax,1)
L43:
  movups %xmm1,(%r9,%rax,1)
  movups 0x4(%rdi,%rax,1),%xmm0
  movups (%rdi,%rax,1),%xmm5
  subps  %xmm5,%xmm0
  movups %xmm0,(%rsi,%rax,1)
  add    $0x10,%rax
  cmp    %rdx,%rax
  jne    L43
  mov    -0x44(%rsp),%ecx
  mov    %ecx,%edx
  and    $0xfffffffc,%edx
  lea    0x1(%rdx),%eax
  cmp    %ecx,%edx
  je     L164
  mov    -0x1c(%rsp),%r8d
  sub    %edx,%r8d
  lea    -0x1(%r8),%ecx
  cmp    $0x2,%r8d
  je     L181
L197:
  movq   $0x0,(%r9,%rdx,4)
  movq   0x4(%rdi,%rdx,4),%xmm0
  movq   (%rdi,%rdx,4),%xmm1
  subps  %xmm1,%xmm0
  movlps %xmm0,(%rsi,%rdx,4)
  mov    %ecx,%edx
  and    $0xfffffffe,%edx
  add    %edx,%eax
  cmp    %ecx,%edx
  je     L164
L181:
  sub    $0x1,%eax
  cltq
  movl   $0x0,(%r9,%rax,4)
  movss  0x4(%rdi,%rax,4),%xmm0
  subss  (%rdi,%rax,4),%xmm0
  movss  %xmm0,(%rsi,%rax,4)
L164:
  imul   -0x1c(%rsp),%r10d
  movslq %r10d,%rax
  shl    $0x2,%rax
  movl   $0x0,-0x4(%r9,%rax,1)
  movl   $0x0,-0x4(%rsi,%rax,1)
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
  nopl   0x0(%rax,%rax,1)
L57:
  mov    -0x10(%rsp),%r11
  mov    -0x50(%rsp),%rax
  mov    -0x18(%rsp),%rbx
  add    %rax,%r11
  nopw   0x0(%rax,%rax,1)
L59:
  movss  0x4(%rdi,%rax,1),%xmm0
  subss  (%rdi,%rax,1),%xmm0
  movss  %xmm0,(%r9,%rax,1)
  movss  (%rbx,%rax,1),%xmm0
  subss  (%rdi,%rax,1),%xmm0
  movss  %xmm0,(%rsi,%rax,1)
  add    $0x4,%rax
  cmp    %r11,%rax
  jne    L59
  jmp    L104
L200:
  mov    -0x38(%rsp),%r14d
  xor    %r11d,%r11d
  xor    %eax,%eax
  jmp    L110
L69:
  mov    -0x34(%rsp),%ecx
  lea    0x1(%r12,%rcx,1),%rcx
  shl    $0x2,%rcx
  jmp    L44
  nopl   0x0(%rax)
L275:
  add    $0x4,%rdx
L44:
  movss  0x4(%rdi,%rax,1),%xmm0
  subss  (%rdi,%rax,1),%xmm0
  movss  %xmm0,(%r9,%rax,1)
  movl   $0x0,(%rsi,%rax,1)
  mov    %rdx,%rax
  cmp    %rcx,%rdx
  jne    L275
  jmp    L388
L158:
  movslq %r10d,%rax
  mov    -0x1c(%rsp),%r11d
  mov    $0x1,%edx
  lea    0x0(,%rax,4),%rcx
  lea    -0x4(,%rax,4),%rax
  lea    (%rdi,%rcx,1),%r8
  nopw   0x0(%rax,%rax,1)
L281:
  movl   $0x0,(%r9,%rax,1)
  movss  (%r8,%rax,1),%xmm0
  add    $0x1,%edx
  subss  (%rdi,%rax,1),%xmm0
  movss  %xmm0,(%rsi,%rax,1)
  add    %rcx,%rax
  cmp    %edx,%r11d
  jne    L281
  jmp    L164
L294:
  mov    -0x44(%rsp),%edx
  xor    %eax,%eax
  cs nopw 0x0(%rax,%rax,1)
L340:
  movl   $0x0,(%r9,%rax,4)
  movss  0x4(%rdi,%rax,4),%xmm0
  subss  (%rdi,%rax,4),%xmm0
  movss  %xmm0,(%rsi,%rax,4)
  add    $0x1,%rax
  cmp    %rdx,%rax
  jne    L340
  jmp    L164
L142:
  lea    -0x2(%r10),%eax
  mov    %eax,-0x34(%rsp)
  mov    -0x38(%rsp),%eax
  test   %eax,%eax
  jg     L258
  jmp    L388
L173:
  mov    -0x38(%rsp),%ecx
  xor    %edx,%edx
  xor    %eax,%eax
  jmp    L346
L3:
  mov    -0x44(%rsp),%ecx
  mov    $0x1,%eax
  xor    %edx,%edx
  jmp    L197
```

assistant: ```c
void forward_gradient(const float *f, float *fx, float *fy, const int nx, const int ny) {
  for (int i = 0; i < ny - 1; i++) {
    for (int j = 0; j < nx - 1; j++) {
      const int p = i * nx + j;
      const int p1 = p + 1;
      const int p2 = p + nx;
      fx[p] = f[p1] - f[p];
      fy[p] = f[p2] - f[p];
    }
  }
  for (int j = 0; j < nx - 1; j++) {
    const int p = (ny - 1) * nx + j;
    fx[p] = f[p + 1] - f[p];
    fy[p] = 0;
  }
  for (int i = 1; i < ny; i++) {
    const int p = i * nx - 1;
    fx[p] = 0;
    fy[p] = f[p + nx] - f[p];
  }
  fx[ny * nx - 1] = 0;
  fy[ny * nx - 1] = 0;
}
```