user: 这段汇编代码用C语言表示是什么样的:

```asm
<FFTNXCorr>:
  endbr64
  push   %r15
  push   %r14
  mov    %rdx,%r14
  push   %r13
  mov    %rsi,%r13
  push   %r12
  push   %rbp
  push   %rbx
  mov    %rcx,%rbx
  sub    $0x28,%rsp
  cmp    %rsi,%rcx
  mov    %rdi,0x18(%rsp)
  mov    %rsi,%rdi
  cmovae %rcx,%rdi
  mov    %r8,0x8(%rsp)
  call   <nextpow2@plt>
  mov    %rax,%r12
  add    $0x1,%rax
  lea    0x0(,%rax,8),%ebp
  mov    %rax,0x10(%rsp)
  mov    %ebp,%edi
  call   <safe_malloc@plt>
  mov    %ebp,%edi
  mov    %rax,%r15
  call   <safe_malloc@plt>
  mov    0x18(%rsp),%r10
  mov    %rax,%rbp
  lea    -0x1(%r13),%rax
  test   %rax,%rax
  mov    %rax,(%rsp)
  js     L98
  lea    -0x2(%r13),%rdi
  mov    %rax,%rdx
  mov    $0x4,%eax
  cmp    $0xffffffffffffffff,%rdi
  lea    0x0(,%r13,4),%rcx
  mov    %rax,%r11
  cmovge %rcx,%r11
  sub    %rcx,%rax
  lea    (%rcx,%r15,1),%rsi
  lea    (%r10,%r11,1),%r8
  xor    %r11d,%r11d
  cmp    $0xffffffffffffffff,%rdi
  cmovl  %r11,%rax
  lea    -0x4(%rsi,%rax,1),%rax
  cmp    %rax,%r8
  setbe  %r11b
  cmp    %rsi,%r10
  setae  %al
  or     %r11b,%al
  je     L238
  cmp    $0xffffffffffffffff,%rdi
  setge  %r11b
  cmpq   $0x2,(%rsp)
  seta   %al
  test   %al,%r11b
  je     L238
  cmp    $0xffffffffffffffff,%rdi
  mov    $0x1,%edi
  mov    %r10,%rax
  cmovge %r13,%rdi
  lea    -0x10(%r10,%rsi,1),%r11
  mov    %rdi,%rcx
  shr    $0x2,%rcx
  shl    $0x4,%rcx
  add    %r10,%rcx
  nopl   (%rax)
L137:
  movups (%rax),%xmm0
  mov    %r11,%rdx
  sub    %rax,%rdx
  add    $0x10,%rax
  shufps $0x1b,%xmm0,%xmm0
  movups %xmm0,(%rdx)
  cmp    %rcx,%rax
  jne    L137
  mov    (%rsp),%rdx
  mov    %rdi,%rax
  and    $0xfffffffffffffffc,%rax
  lea    (%r10,%rax,4),%rcx
  sub    %rax,%rdx
  cmp    %rax,%rdi
  je     L98
  movss  (%rcx),%xmm0
  lea    -0x1(%rdx),%rax
  movss  %xmm0,(%r15,%rdx,4)
  test   %rdx,%rdx
  je     L98
  movss  0x4(%rcx),%xmm0
  lea    0x0(,%rax,4),%rdi
  movss  %xmm0,(%r15,%rax,4)
  cmp    $0x1,%rdx
  je     L98
  movss  0x8(%rcx),%xmm0
  movss  %xmm0,-0x4(%r15,%rdi,1)
L98:
  lea    (%r12,%r12,1),%rcx
  cmp    %rcx,%r13
  jge    L251
  mov    %rcx,%rdx
  lea    (%r15,%r13,4),%rdi
  xor    %esi,%esi
  mov    %rcx,0x18(%rsp)
  sub    %r13,%rdx
  shl    $0x2,%rdx
  call   <memset@plt>
  mov    0x18(%rsp),%rcx
L251:
  lea    (%r12,%r12,1),%r13d
  mov    %r15,%rdi
  mov    %rcx,0x18(%rsp)
  mov    %r13d,%esi
  call   <RealFFT@plt>
  test   %rbx,%rbx
  mov    0x18(%rsp),%rcx
  jle    L70
  lea    0x4(%r14),%rdx
  mov    %rbp,%rax
  sub    %rdx,%rax
  cmp    $0x8,%rax
  jbe    L277
  lea    -0x1(%rbx),%rax
  cmp    $0x2,%rax
  jbe    L277
  mov    %rbx,%rdx
  mov    %r14,%rsi
  mov    %rbp,%rax
  shr    $0x2,%rdx
  sub    %rbp,%rsi
  shl    $0x4,%rdx
  add    %rbp,%rdx
  nopl   0x0(%rax,%rax,1)
L200:
  movups (%rax,%rsi,1),%xmm7
  add    $0x10,%rax
  movups %xmm7,-0x10(%rax)
  cmp    %rdx,%rax
  jne    L200
  mov    %rbx,%rax
  and    $0xfffffffffffffffc,%rax
  test   $0x3,%bl
  je     L70
  movss  (%r14,%rax,4),%xmm0
  lea    0x1(%rax),%rdx
  movss  %xmm0,0x0(%rbp,%rax,4)
  cmp    %rdx,%rbx
  jle    L70
  movss  (%r14,%rdx,4),%xmm0
  add    $0x2,%rax
  lea    0x0(,%rdx,4),%rsi
  movss  %xmm0,0x0(%rbp,%rdx,4)
  cmp    %rax,%rbx
  jle    L70
  movss  0x4(%r14,%rsi,1),%xmm0
  movss  %xmm0,0x4(%rbp,%rsi,1)
L70:
  cmp    %rbx,%rcx
  jle    L124
  sub    %rbx,%rcx
  lea    0x0(%rbp,%rbx,4),%rdi
  xor    %esi,%esi
  lea    0x0(,%rcx,4),%rdx
  call   <memset@plt>
L124:
  mov    %r13d,%esi
  mov    %rbp,%rdi
  call   <RealFFT@plt>
  test   %r12,%r12
  js     L149
  lea    0x20(%rbp),%rdx
  lea    0x20(%r15),%rcx
  mov    %r15,%rax
  cmp    %rdx,%r15
  setae  %dl
  cmp    %rcx,%rbp
  setae  %cl
  or     %cl,%dl
  je     L229
  cmp    $0x2,%r12
  jbe    L229
  mov    0x10(%rsp),%rdi
  lea    0x10(%r15),%rcx
  lea    0x10(%rbp),%rsi
  mov    %rbp,%rdx
  shr    $0x2,%rdi
  shl    $0x5,%rdi
  add    %rbp,%rdi
L12:
  movups (%rax),%xmm1
  movups (%rcx),%xmm6
  add    $0x20,%rdx
  add    $0x20,%rax
  movups -0x20(%rdx),%xmm3
  add    $0x20,%rcx
  add    $0x20,%rsi
  movaps %xmm1,%xmm0
  shufps $0xdd,%xmm6,%xmm1
  movaps %xmm1,%xmm5
  shufps $0x88,%xmm6,%xmm0
  movups -0x20(%rsi),%xmm6
  movaps %xmm3,%xmm4
  movaps %xmm0,%xmm2
  shufps $0x88,%xmm6,%xmm4
  shufps $0xdd,%xmm6,%xmm3
  mulps  %xmm4,%xmm2
  mulps  %xmm3,%xmm5
  mulps  %xmm4,%xmm1
  mulps  %xmm3,%xmm0
  subps  %xmm5,%xmm2
  addps  %xmm1,%xmm0
  movaps %xmm2,%xmm1
  unpcklps %xmm0,%xmm1
  unpckhps %xmm0,%xmm2
  movups %xmm1,-0x20(%rax)
  movups %xmm2,-0x20(%rcx)
  cmp    %rdx,%rdi
  jne    L12
  mov    0x10(%rsp),%rsi
  mov    %rsi,%rax
  and    $0xfffffffffffffffc,%rax
  and    $0x3,%esi
  je     L149
  lea    0x0(,%rax,8),%rdx
  lea    0x4(%rdx),%rcx
  lea    (%r15,%rdx,1),%rdi
  add    %rbp,%rdx
  lea    (%r15,%rcx,1),%rsi
  add    %rbp,%rcx
  movss  (%rdi),%xmm0
  movss  (%rdx),%xmm2
  movss  (%rsi),%xmm1
  movss  (%rcx),%xmm3
  mulss  %xmm0,%xmm2
  mulss  %xmm1,%xmm3
  subss  %xmm3,%xmm2
  movss  %xmm2,(%rdi)
  mulss  (%rdx),%xmm1
  lea    0x1(%rax),%rdx
  mulss  (%rcx),%xmm0
  addss  %xmm1,%xmm0
  movss  %xmm0,(%rsi)
  cmp    %r12,%rdx
  jg     L149
  shl    $0x3,%rdx
  add    $0x2,%rax
  lea    0x4(%rdx),%rcx
  lea    (%r15,%rdx,1),%rdi
  add    %rbp,%rdx
  lea    (%r15,%rcx,1),%rsi
  add    %rbp,%rcx
  movss  (%rdi),%xmm0
  movss  (%rdx),%xmm2
  movss  (%rsi),%xmm1
  movss  (%rcx),%xmm3
  mulss  %xmm0,%xmm2
  mulss  %xmm1,%xmm3
  subss  %xmm3,%xmm2
  movss  %xmm2,(%rdi)
  mulss  (%rcx),%xmm0
  mulss  (%rdx),%xmm1
  addss  %xmm1,%xmm0
  movss  %xmm0,(%rsi)
  cmp    %rax,%r12
  jl     L149
  shl    $0x3,%rax
  lea    0x4(%rax),%rdx
  lea    (%r15,%rax,1),%rsi
  add    %rbp,%rax
  lea    (%r15,%rdx,1),%rcx
  add    %rbp,%rdx
  movss  (%rsi),%xmm0
  movss  (%rax),%xmm2
  movss  (%rcx),%xmm1
  movss  (%rdx),%xmm3
  mulss  %xmm0,%xmm2
  mulss  %xmm1,%xmm3
  subss  %xmm3,%xmm2
  movss  %xmm2,(%rsi)
  mulss  (%rdx),%xmm0
  mulss  (%rax),%xmm1
  addss  %xmm1,%xmm0
  movss  %xmm0,(%rcx)
L149:
  mov    %r13d,%esi
  mov    %r15,%rdi
  call   <RealIFFT@plt>
  mov    (%rsp),%r12
  add    %rbx,%r12
  test   %r12,%r12
  jle    L22
  mov    0x8(%rsp),%rbx
  lea    0x4(%r15),%rdx
  mov    %rbx,%rax
  sub    %rdx,%rax
  cmp    $0x8,%rax
  jbe    L118
  lea    -0x1(%r12),%rax
  cmp    $0x2,%rax
  jbe    L118
  mov    %r12,%rdx
  sub    %r15,%rbx
  mov    %r15,%rax
  shr    $0x2,%rdx
  mov    %rbx,%rcx
  shl    $0x4,%rdx
  add    %r15,%rdx
  nopl   (%rax)
L121:
  movups (%rax),%xmm5
  movups %xmm5,(%rcx,%rax,1)
  add    $0x10,%rax
  cmp    %rdx,%rax
  jne    L121
  mov    %r12,%rax
  and    $0xfffffffffffffffc,%rax
  test   $0x3,%r12b
  je     L22
  movss  (%r15,%rax,4),%xmm0
  mov    0x8(%rsp),%rbx
  lea    0x1(%rax),%rdx
  movss  %xmm0,(%rbx,%rax,4)
  cmp    %rdx,%r12
  jle    L22
  movss  (%r15,%rdx,4),%xmm0
  add    $0x2,%rax
  lea    0x0(,%rdx,4),%rcx
  movss  %xmm0,(%rbx,%rdx,4)
  cmp    %rax,%r12
  jle    L22
  movss  0x4(%r15,%rcx,1),%xmm0
  movss  %xmm0,0x4(%rbx,%rcx,1)
L22:
  mov    %r15,%rdi
  call   <safe_free@plt>
  mov    %rbp,%rdi
  call   <safe_free@plt>
  add    $0x28,%rsp
  mov    %r12,%rax
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
  nopl   0x0(%rax)
L277:
  lea    0x0(%rbp,%rbx,4),%rdx
  mov    %rbp,%rax
  sub    %rbp,%r14
  nopl   0x0(%rax,%rax,1)
L292:
  movss  (%r14,%rax,1),%xmm0
  add    $0x4,%rax
  movss  %xmm0,-0x4(%rax)
  cmp    %rdx,%rax
  jne    L292
  jmp    L70
  nopl   0x0(%rax)
L229:
  lea    0x4(%rbp),%rcx
  mov    %rbp,%rsi
  lea    0x8(%r15,%r12,8),%rdi
  mov    %r15,%rax
  sub    %r15,%rsi
  sub    %r15,%rcx
  nopl   (%rax)
L65:
  lea    (%rsi,%rax,1),%rdx
  lea    (%rcx,%rax,1),%r8
  movss  (%rax),%xmm0
  movss  0x4(%rax),%xmm1
  movss  (%rdx),%xmm2
  movss  (%r8),%xmm3
  add    $0x8,%rax
  mulss  %xmm0,%xmm2
  mulss  %xmm1,%xmm3
  subss  %xmm3,%xmm2
  movss  %xmm2,-0x8(%rax)
  mulss  (%r8),%xmm0
  mulss  (%rdx),%xmm1
  addss  %xmm1,%xmm0
  movss  %xmm0,-0x4(%rax)
  cmp    %rdi,%rax
  jne    L65
  jmp    L149
  nopl   0x0(%rax,%rax,1)
L118:
  mov    0x8(%rsp),%r13
  lea    (%r15,%r12,4),%rdx
  mov    %r15,%rax
  sub    %r15,%r13
  nop
L176:
  movss  (%rax),%xmm0
  movss  %xmm0,0x0(%r13,%rax,1)
  add    $0x4,%rax
  cmp    %rdx,%rax
  jne    L176
  jmp    L22
  nopl   0x0(%rax)
L238:
  add    %r10,%rcx
  add    %r15,%rcx
  cs nopw 0x0(%rax,%rax,1)
L288:
  add    $0x4,%r10
  mov    %rcx,%rax
  movss  -0x4(%r10),%xmm0
  sub    %r10,%rax
  movss  %xmm0,(%rax)
  sub    $0x1,%rdx
  jae    L288
  jmp    L98
```

assistant: ```c
unsigned long FFTNXCorr(float *x1, unsigned long n1, float *x2, unsigned long n2, float *y) {
  register float r1, i1;
  float *tmp1;
  float *tmp2;
  long C, D, Nx, Ny;
  Nx = nextpow2((((n1) > (n2)) ? (n1) : (n2)));
  tmp1 = (float *)safe_malloc(sizeof(float) * (2 * Nx + 2));
  tmp2 = (float *)safe_malloc(sizeof(float) * (2 * Nx + 2));
  for (C = n1 - 1; C >= 0; C--) {
    tmp1[C] = *(x1++);
  }
  for (C = n1; C < 2 * Nx; C++)
    tmp1[C] = 0.0;
  RealFFT(tmp1, 2 * Nx);
  for (C = 0; C < (long)n2; C++) {
    tmp2[C] = x2[C];
  }
  for (C = n2; C < 2 * Nx; C++)
    tmp2[C] = 0.0;
  RealFFT(tmp2, 2 * Nx);
  for (C = 0; C <= Nx; C++) {
    D = C << 1;
    r1 = tmp1[D];
    i1 = tmp1[1 + D];
    tmp1[D] = r1 * tmp2[D] - i1 * tmp2[1 + D];
    tmp1[1 + D] = r1 * tmp2[1 + D] + i1 * tmp2[D];
  }
  RealIFFT(tmp1, 2 * Nx);
  Ny = n1 + n2 - 1;
  for (C = 0; C < Ny; C++)
    y[C] = tmp1[C];
  safe_free(tmp1);
  safe_free(tmp2);
  return Ny;
}
```