user: 请从给定的汇编指令推导出C源代码：

```asm
<IV2ZVqsortDown>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  sub    $0x18,%rsp
  mov    %edi,0x4(%rsp)
  mov    %rsi,%rbp
  mov    %rdx,%r12
  mov    %rcx,%rbx
  test   %edi,%edi
  jle    L121
  mov    0x4(%rsp),%r15d
  mov    %r15d,%edi
  call   <Icentervalue@plt>
  mov    %eax,%edx
  lea    -0x1(%r15),%eax
  mov    %eax,%esi
  mov    %eax,0xc(%rsp)
  mov    %eax,%r10d
  mov    $0x0,%r15d
  mov    $0x1,%r14d
  mov    $0x0,%edi
  movl   $0x0,0x8(%rsp)
L148:
  mov    %edi,%r9d
  mov    0x0(%rbp,%rdi,4),%eax
  cmp    %edx,%eax
  jge    L133
  movslq %esi,%rax
  jmp    L35
L121:
  call   <IV2ZVisortDown@plt>
  jmp    L154
L133:
  cmp    %edx,%eax
  je     L127
L5:
  mov    %r14d,%r9d
  jmp    L82
L127:
  mov    0x8(%rsp),%r11d
  movslq %r11d,%rax
  shl    $0x2,%rax
  lea    0x0(%rbp,%rax,1),%rcx
  mov    (%rcx),%r8d
  mov    %edx,(%rcx)
  mov    %r8d,0x0(%rbp,%rdi,4)
  add    %r12,%rax
  mov    (%rax),%ecx
  mov    (%r12,%rdi,4),%r8d
  mov    %r8d,(%rax)
  mov    %ecx,(%r12,%rdi,4)
  lea    (%r11,%r11,1),%ecx
  movslq %ecx,%rcx
  lea    (%rbx,%rcx,8),%r9
  movsd  (%r9),%xmm0
  movslq %r15d,%rax
  shl    $0x3,%rax
  lea    (%rbx,%rax,1),%r8
  movsd  (%r8),%xmm1
  movsd  %xmm1,(%r9)
  movsd  %xmm0,(%r8)
  lea    0x8(%rbx,%rcx,8),%rcx
  movsd  (%rcx),%xmm0
  lea    0x8(%rbx,%rax,1),%rax
  movsd  (%rax),%xmm1
  movsd  %xmm1,(%rcx)
  movsd  %xmm0,(%rax)
  add    $0x1,%r11d
  mov    %r11d,0x8(%rsp)
  jmp    L5
L99:
  lea    -0x1(%r8),%esi
  sub    $0x1,%rax
  cmp    %edi,%eax
  jl     L45
L35:
  mov    %eax,%r8d
  mov    %eax,%esi
  mov    0x0(%rbp,%rax,4),%ecx
  cmp    %edx,%ecx
  jg     L160
  jne    L99
  movslq %r10d,%rcx
  shl    $0x2,%rcx
  lea    0x0(%rbp,%rcx,1),%rsi
  mov    (%rsi),%r11d
  mov    %r11d,0x0(%rbp,%rax,4)
  mov    %edx,(%rsi)
  mov    (%r12,%rax,4),%esi
  add    %r12,%rcx
  mov    (%rcx),%r11d
  mov    %r11d,(%r12,%rax,4)
  mov    %esi,(%rcx)
  lea    (%r8,%r8,1),%ecx
  movslq %ecx,%rcx
  shl    $0x3,%rcx
  lea    (%rbx,%rcx,1),%r13
  movsd  0x0(%r13),%xmm0
  lea    (%r10,%r10,1),%esi
  movslq %esi,%rsi
  lea    (%rbx,%rsi,8),%r11
  movsd  (%r11),%xmm1
  movsd  %xmm1,0x0(%r13)
  movsd  %xmm0,(%r11)
  lea    0x8(%rbx,%rcx,1),%r11
  movsd  (%r11),%xmm0
  lea    0x8(%rbx,%rsi,8),%rcx
  movsd  (%rcx),%xmm1
  movsd  %xmm1,(%r11)
  movsd  %xmm0,(%rcx)
  sub    $0x1,%r10d
  jmp    L99
L160:
  cmp    %edi,%eax
  jl     L45
  mov    0x0(%rbp,%rdi,4),%r8d
  cltq
  shl    $0x2,%rax
  lea    0x0(%rbp,%rax,1),%rcx
  mov    (%rcx),%r9d
  mov    %r9d,0x0(%rbp,%rdi,4)
  mov    %r8d,(%rcx)
  mov    (%r12,%rdi,4),%ecx
  add    %r12,%rax
  mov    (%rax),%r8d
  mov    %r8d,(%r12,%rdi,4)
  mov    %ecx,(%rax)
  movslq %r15d,%rcx
  shl    $0x3,%rcx
  lea    (%rbx,%rcx,1),%r9
  movsd  (%r9),%xmm0
  lea    (%rsi,%rsi,1),%eax
  cltq
  lea    (%rbx,%rax,8),%r8
  movsd  (%r8),%xmm1
  movsd  %xmm1,(%r9)
  movsd  %xmm0,(%r8)
  lea    0x8(%rbx,%rcx,1),%rcx
  movsd  (%rcx),%xmm0
  lea    0x8(%rbx,%rax,8),%rax
  movsd  (%rax),%xmm1
  movsd  %xmm1,(%rcx)
  movsd  %xmm0,(%rax)
  mov    %r14d,%r9d
  sub    $0x1,%esi
L82:
  add    $0x1,%rdi
  add    $0x1,%r14d
  add    $0x2,%r15d
  cmp    %esi,%r9d
  jle    L148
L45:
  mov    %r9d,%edi
  mov    0x8(%rsp),%eax
  sub    %eax,%edi
  cmp    %eax,%edi
  cmovle %edi,%eax
  mov    %r9d,%edx
  sub    %eax,%edx
  test   %eax,%eax
  je     L44
  movslq %edx,%rdx
  shl    $0x2,%rdx
  mov    %eax,%eax
  lea    0x0(,%rax,4),%rcx
  mov    $0x0,%eax
L102:
  mov    0x0(%rbp,%rax,1),%r8d
  mov    0x0(%rbp,%rdx,1),%r11d
  mov    %r11d,0x0(%rbp,%rax,1)
  mov    %r8d,0x0(%rbp,%rdx,1)
  mov    (%r12,%rax,1),%r8d
  mov    (%r12,%rdx,1),%r11d
  mov    %r11d,(%r12,%rax,1)
  mov    %r8d,(%r12,%rdx,1)
  movsd  (%rbx,%rax,4),%xmm0
  movsd  (%rbx,%rdx,4),%xmm1
  movsd  %xmm1,(%rbx,%rax,4)
  movsd  %xmm0,(%rbx,%rdx,4)
  movsd  0x8(%rbx,%rax,4),%xmm0
  movsd  0x8(%rbx,%rdx,4),%xmm1
  movsd  %xmm1,0x8(%rbx,%rax,4)
  movsd  %xmm0,0x8(%rbx,%rdx,4)
  add    $0x4,%rax
  add    $0x4,%rdx
  cmp    %rcx,%rax
  jne    L102
L44:
  mov    %r10d,%r13d
  sub    %esi,%r13d
  mov    0xc(%rsp),%ecx
  sub    %r10d,%ecx
  cmp    %r13d,%ecx
  cmovg  %r13d,%ecx
  mov    0x4(%rsp),%esi
  sub    %ecx,%esi
  test   %ecx,%ecx
  je     L4
  movslq %r9d,%rax
  shl    $0x2,%rax
  movslq %esi,%rsi
  lea    0x0(,%rsi,4),%rdx
  lea    -0x1(%rcx),%ecx
  lea    0x1(%rsi,%rcx,1),%r8
  shl    $0x2,%r8
L80:
  mov    0x0(%rbp,%rax,1),%ecx
  mov    0x0(%rbp,%rdx,1),%esi
  mov    %esi,0x0(%rbp,%rax,1)
  mov    %ecx,0x0(%rbp,%rdx,1)
  mov    (%r12,%rax,1),%ecx
  mov    (%r12,%rdx,1),%esi
  mov    %esi,(%r12,%rax,1)
  mov    %ecx,(%r12,%rdx,1)
  movsd  (%rbx,%rax,4),%xmm0
  movsd  (%rbx,%rdx,4),%xmm1
  movsd  %xmm1,(%rbx,%rax,4)
  movsd  %xmm0,(%rbx,%rdx,4)
  movsd  0x8(%rbx,%rax,4),%xmm0
  movsd  0x8(%rbx,%rdx,4),%xmm1
  movsd  %xmm1,0x8(%rbx,%rax,4)
  movsd  %xmm0,0x8(%rbx,%rdx,4)
  add    $0x4,%rax
  add    $0x4,%rdx
  cmp    %r8,%rdx
  jne    L80
L4:
  mov    %rbx,%rcx
  mov    %r12,%rdx
  mov    %rbp,%rsi
  call   <IV2ZVqsortDown>
  mov    0x4(%rsp),%edi
  movslq %edi,%rcx
  movslq %r13d,%rax
  sub    %rax,%rcx
  shl    $0x2,%rcx
  mov    %edi,%eax
  sub    %r13d,%eax
  add    %eax,%eax
  cltq
  lea    (%rbx,%rax,8),%rax
  lea    (%r12,%rcx,1),%rdx
  lea    0x0(%rbp,%rcx,1),%rsi
  mov    %rax,%rcx
  mov    %r13d,%edi
  call   <IV2ZVqsortDown>
L154:
  add    $0x18,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
```

assistant: ```c
void IV2ZVqsortDown(int n, int ivec1[], int ivec2[], double zvec[]) {
  double dtemp;
  int a, b, c, d, itemp, l, h, s, v;
  if (n <= 0) {
    IV2ZVisortDown(n, ivec1, ivec2, zvec);
  } else {
    v = Icentervalue(n, ivec1);
    a = b = 0;
    c = d = n - 1;
    for (;;) {
      while (b <= c && ivec1[b] >= v) {
        if (ivec1[b] == v) {
          {
            itemp = ivec1[(a)];
            ivec1[(a)] = ivec1[(b)];
            ivec1[(b)] = itemp;
            itemp = ivec2[(a)];
            ivec2[(a)] = ivec2[(b)];
            ivec2[(b)] = itemp;
            dtemp = zvec[2 * (a)];
            zvec[2 * (a)] = zvec[2 * (b)];
            zvec[2 * (b)] = dtemp;
            dtemp = zvec[2 * (a) + 1];
            zvec[2 * (a) + 1] = zvec[2 * (b) + 1];
            zvec[2 * (b) + 1] = dtemp;
          }
          a++;
        }
        b++;
      }
      while (c >= b && ivec1[c] <= v) {
        if (ivec1[c] == v) {
          {
            itemp = ivec1[(c)];
            ivec1[(c)] = ivec1[(d)];
            ivec1[(d)] = itemp;
            itemp = ivec2[(c)];
            ivec2[(c)] = ivec2[(d)];
            ivec2[(d)] = itemp;
            dtemp = zvec[2 * (c)];
            zvec[2 * (c)] = zvec[2 * (d)];
            zvec[2 * (d)] = dtemp;
            dtemp = zvec[2 * (c) + 1];
            zvec[2 * (c) + 1] = zvec[2 * (d) + 1];
            zvec[2 * (d) + 1] = dtemp;
          }
          d--;
        }
        c--;
      }
      if (b > c) {
        break;
      }
      {
        itemp = ivec1[(b)];
        ivec1[(b)] = ivec1[(c)];
        ivec1[(c)] = itemp;
        itemp = ivec2[(b)];
        ivec2[(b)] = ivec2[(c)];
        ivec2[(c)] = itemp;
        dtemp = zvec[2 * (b)];
        zvec[2 * (b)] = zvec[2 * (c)];
        zvec[2 * (c)] = dtemp;
        dtemp = zvec[2 * (b) + 1];
        zvec[2 * (b) + 1] = zvec[2 * (c) + 1];
        zvec[2 * (c) + 1] = dtemp;
      }
      b++;
      c--;
    }
    s = (a <= b - a) ? a : b - a;
    for (l = 0, h = b - s; s != 0; s--) {
      {
        itemp = ivec1[(l)];
        ivec1[(l)] = ivec1[(h)];
        ivec1[(h)] = itemp;
        itemp = ivec2[(l)];
        ivec2[(l)] = ivec2[(h)];
        ivec2[(h)] = itemp;
        dtemp = zvec[2 * (l)];
        zvec[2 * (l)] = zvec[2 * (h)];
        zvec[2 * (h)] = dtemp;
        dtemp = zvec[2 * (l) + 1];
        zvec[2 * (l) + 1] = zvec[2 * (h) + 1];
        zvec[2 * (h) + 1] = dtemp;
      }
      l++;
      h++;
    }
    s = ((d - c) <= (n - 1 - d)) ? (d - c) : (n - 1 - d);
    for (l = b, h = n - s; s != 0; s--) {
      {
        itemp = ivec1[(l)];
        ivec1[(l)] = ivec1[(h)];
        ivec1[(h)] = itemp;
        itemp = ivec2[(l)];
        ivec2[(l)] = ivec2[(h)];
        ivec2[(h)] = itemp;
        dtemp = zvec[2 * (l)];
        zvec[2 * (l)] = zvec[2 * (h)];
        zvec[2 * (h)] = dtemp;
        dtemp = zvec[2 * (l) + 1];
        zvec[2 * (l) + 1] = zvec[2 * (h) + 1];
        zvec[2 * (h) + 1] = dtemp;
      }
      l++;
      h++;
    }
    IV2ZVqsortDown(b - a, ivec1, ivec2, zvec);
    IV2ZVqsortDown(d - c, ivec1 + n - (d - c), ivec2 + n - (d - c), zvec + 2 * (n - (d - c)));
  }
  return;
}
```