user: 请将这段汇编代码片段转换成等效的C代码：

```asm
<matexp>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  sub    $0x38,%rsp
  mov    %rdi,%r12
  movsd  %xmm0,(%rsp)
  mov    %esi,%ebx
  mov    %edx,%r15d
  mov    %rcx,%r14
  mov    %fs:0x28,%rax
  mov    %rax,0x28(%rsp)
  xor    %eax,%eax
  lea    -0x2(%rdx),%eax
  cmp    $0x1d,%eax
  ja     L148
L42:
  mov    %r12,0x10(%rsp)
  mov    %r14,0x18(%rsp)
  mov    %ebx,%eax
  imul   %ebx,%eax
  mov    %eax,0xc(%rsp)
  test   %eax,%eax
  jle    L125
  mov    %r12,%rbp
  lea    -0x1(%rax),%eax
  lea    0x8(%r12,%rax,8),%r13
  mov    %r15d,%eax
  neg    %eax
  mov    %eax,0x8(%rsp)
L5:
  movsd  (%rsp),%xmm0
  mulsd  0x0(%rbp),%xmm0
  mov    0x8(%rsp),%edi
  call   <ldexp@plt>
  movsd  %xmm0,0x0(%rbp)
  add    $0x8,%rbp
  cmp    %r13,%rbp
  jne    L5
  mov    %ebx,%r9d
  mov    %ebx,%r8d
  mov    %ebx,%ecx
  mov    %r14,%rdx
  mov    %r12,%rsi
  mov    %r12,%rdi
  call   <matby@plt>
  mov    0xc(%rsp),%edx
  mov    $0x0,%eax
  movsd  D15(%rip),%xmm1
L110:
  movapd %xmm1,%xmm0
  mulsd  (%r14,%rax,8),%xmm0
  addsd  (%r12,%rax,8),%xmm0
  movsd  %xmm0,(%r12,%rax,8)
  add    $0x1,%rax
  cmp    %rdx,%rax
  jne    L110
L131:
  test   %ebx,%ebx
  jle    L72
  movslq %ebx,%rax
  lea    0x8(,%rax,8),%rcx
  mov    %r12,%rax
  mov    $0x0,%edx
  movsd  D5(%rip),%xmm1
L2:
  movapd %xmm1,%xmm0
  addsd  (%rax),%xmm0
  movsd  %xmm0,(%rax)
  add    $0x1,%edx
  add    %rcx,%rax
  cmp    %edx,%ebx
  jne    L2
L72:
  test   %r15d,%r15d
  jle    L142
  mov    $0x0,%r13d
  mov    $0x0,%ebp
L133:
  mov    %ebp,(%rsp)
  xor    $0x1,%ebp
  mov    $0x1,%eax
  sub    %ebp,%eax
  cltq
  mov    0x10(%rsp,%rax,8),%rdi
  movslq %ebp,%rax
  mov    0x10(%rsp,%rax,8),%rdx
  mov    %ebx,%r9d
  mov    %ebx,%r8d
  mov    %ebx,%ecx
  mov    %rdi,%rsi
  call   <matby@plt>
  add    $0x1,%r13d
  cmp    %r13d,%r15d
  jne    L133
  cmpl   $0x0,(%rsp)
  je     L83
L142:
  mov    0x28(%rsp),%rax
  sub    %fs:0x28,%rax
  jne    L145
  mov    $0x0,%eax
  add    $0x38,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
L148:
  lea    D0(%rip),%rdi
  call   <error2@plt>
  jmp    L42
L83:
  mov    0xc(%rsp),%eax
  test   %eax,%eax
  jle    L142
  mov    %eax,%edx
  mov    $0x0,%eax
L99:
  movsd  (%r14,%rax,8),%xmm0
  movsd  %xmm0,(%r12,%rax,8)
  add    $0x1,%rax
  cmp    %rax,%rdx
  jne    L99
  jmp    L142
L125:
  mov    %ebx,%r9d
  mov    %ebx,%r8d
  mov    %ebx,%ecx
  mov    %r14,%rdx
  mov    %r12,%rsi
  mov    %r12,%rdi
  call   <matby@plt>
  jmp    L131
L145:
  call   <__stack_chk_fail@plt>
```

tool_calls: name: retrieve_data
arguments: data_tag: D15
datatype: byte[8]
name: retrieve_data
arguments: data_tag: D5
datatype: byte[8]
name: retrieve_data
arguments: data_tag: D0
datatype: string

tool: {"D15": [0x00,0x00,0x00,0x00,0x00,0x00,0xe0,0x3f]}

tool: {"D5": [0x00,0x00,0x00,0x00,0x00,0x00,0xf0,0x3f]}

tool: D0: TimeSquare not good

assistant: ```c
int matexp(double Q[], double t, int n, int TimeSquare, double space[]) {
  int it, i;
  double *T[2];
  if (TimeSquare < 2 || TimeSquare > 31)
    error2("TimeSquare not good");
  T[0] = Q;
  T[1] = space;
  for (i = 0; i < n * n; i++)
    T[0][i] = ldexp(Q[i] * t, -TimeSquare);
  matby(T[0], T[0], T[1], n, n, n);
  for (i = 0; i < n * n; i++)
    T[0][i] += T[1][i] / 2;
  for (i = 0; i < n; i++)
    T[0][i * n + i]++;
  for (i = 0, it = 0; i < TimeSquare; i++) {
    it = !it;
    matby(T[1 - it], T[1 - it], T[it], n, n, n);
  }
  if (it == 1)
    for (i = 0; i < n * n; i++)
      Q[i] = T[1][i];
  return (0);
}
```