user: 请从给定的汇编指令推导出C源代码:

```asm
<longdivision>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  mov    %rsi,%r12
  push   %rbp
  mov    %rcx,%rbp
  push   %rbx
  sub    $0x58,%rsp
  mov    %rdi,0x8(%rsp)
  mov    %rdx,(%rsp)
  mov    %r8,0x18(%rsp)
  mov    %r9d,0x24(%rsp)
  mov    %fs:0x28,%rax
  mov    %rax,0x48(%rsp)
  xor    %eax,%eax
  cmpb   $0x1,(%rdi)
  mov    $0x0,%eax
  movl   $0x0,0x3c(%rsp)
  movl   $0x0,0x40(%rsp)
  movl   $0x0,0x44(%rsp)
  mov    %ax,(%rcx)
  je     L110
  mov    0x8(%rsp),%rbx
  xor    %r14d,%r14d
L104:
  cmpb   $0x0,(%rbx)
  jne    L2
  add    $0x1,%r14d
  add    $0x1,%rbx
  cmp    $0x5,%r14d
  jne    L104
  mov    0x8(%rsp),%rax
  mov    $0x4,%r9d
  lea    0x5(%rax),%rbx
L40:
  xor    %eax,%eax
L52:
  movzbl (%r12,%rax,1),%r13d
  mov    %eax,%r8d
  test   %r13b,%r13b
  jne    L125
  add    $0x1,%rax
  cmp    $0x5,%rax
  jne    L52
  movzbl 0x5(%r12),%edi
  call   <miLookup@plt>
  movzbl (%rbx),%esi
  lea    0x3c(%rsp),%rbx
  movzbl %al,%edi
  mov    %edi,0x20(%rsp)
  call   <bd@plt>
  movslq %r14d,%rcx
  mov    %al,0x2(%rbp)
L103:
  mov    0x8(%rsp),%rax
  mov    0x20(%rsp),%edi
  mov    $0x1,%r15d
  lea    0x3b(%rsp),%r14
  movzbl 0x4(%rax),%eax
  mov    %al,0x43(%rsp)
  movzbl 0x40(%rsp,%rcx,1),%esi
  call   <bd@plt>
  mov    %al,0x3(%rbp)
L91:
  movzbl (%r12,%r15,1),%esi
  movzbl %al,%edi
  call   <bd@plt>
  mov    %al,(%r14,%r15,1)
  add    $0x1,%r15
  cmp    $0x5,%r15
  je     L150
  movzbl 0x3(%rbp),%eax
  jmp    L91
  xchg   %ax,%ax
L150:
  mov    (%rsp),%rax
  movb   $0x0,(%rax)
  xor    %eax,%eax
L64:
  movzbl (%rbx,%rax,1),%edx
  mov    (%rsp),%rcx
  xor    %r13d,%edx
  mov    %dl,0x1(%rcx,%rax,1)
  add    $0x1,%rax
  cmp    $0x4,%rax
  je     L169
  movzbl 0x40(%rsp,%rax,1),%r13d
  jmp    L64
  nopw   0x0(%rax,%rax,1)
L169:
  movslq 0x24(%rsp),%rbx
  mov    0x18(%rsp),%r14
  lea    0x44(%rsp),%r12
  mov    %rbp,%rsi
  mov    %r12,%rdx
  shl    $0x2,%rbx
  lea    (%r14,%rbx,1),%rdi
  call   <modprod@plt>
  lea    0x4(%r14,%rbx,1),%rsi
  lea    -0x4(%r14,%rbx,1),%rcx
  xor    %eax,%eax
L197:
  movzbl (%rcx,%rax,1),%edx
  xor    (%r12,%rax,1),%dl
  mov    %dl,(%rsi,%rax,1)
  add    $0x1,%rax
  cmp    $0x4,%rax
  jne    L197
L100:
  mov    0x48(%rsp),%rax
  sub    %fs:0x28,%rax
  jne    L84
  add    $0x58,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
  cs nopw 0x0(%rax,%rax,1)
L125:
  mov    %r14d,%eax
  movzbl %r13b,%edi
  mov    %r8d,0x10(%rsp)
  sub    %r8d,%eax
  mov    %r9d,0x28(%rsp)
  lea    0x4(%rax),%r15d
  call   <miLookup@plt>
  movzbl (%rbx),%esi
  lea    0x3c(%rsp),%rbx
  movzbl %al,%edi
  mov    %edi,0x20(%rsp)
  call   <bd@plt>
  movslq 0x28(%rsp),%rcx
  movslq 0x10(%rsp),%r8
  mov    %al,0x2(%rbp)
  sub    %rcx,%r8
  mov    %rcx,0x28(%rsp)
  mov    %rcx,%r13
  lea    (%r12,%r8,1),%rcx
  mov    %rcx,0x10(%rsp)
L168:
  mov    0x10(%rsp),%rcx
  movzbl %al,%edi
  movzbl (%rcx,%r13,1),%esi
  call   <bd@plt>
  mov    %al,(%rbx,%r13,1)
  add    $0x1,%r13
  cmp    %r13d,%r15d
  jle    L173
  movzbl 0x2(%rbp),%eax
  jmp    L168
  nopw   0x0(%rax,%rax,1)
L173:
  mov    0x28(%rsp),%rax
  movslq %r14d,%rcx
  lea    0x40(%rsp),%rdi
  mov    %rcx,%rsi
  sub    %rax,%rsi
  add    0x8(%rsp),%rsi
L178:
  movzbl (%rsi,%rax,1),%edx
  xor    (%rbx,%rax,1),%dl
  mov    %dl,(%rdi,%rax,1)
  add    $0x1,%rax
  cmp    %eax,%r15d
  jg     L178
  movzbl 0x40(%rsp),%r13d
  jmp    L103
  cs nopw 0x0(%rax,%rax,1)
L110:
  movzbl 0x1(%rsi),%edi
  xor    %r14d,%r14d
  lea    0x3c(%rsp),%rbx
  call   <miLookup@plt>
  movzbl %al,%r13d
  mov    %r13d,%r15d
L157:
  movzbl 0x2(%r12,%r14,1),%esi
  mov    %r13d,%edi
  call   <bd@plt>
  mov    %al,(%rbx,%r14,1)
  add    $0x1,%r14
  cmp    $0x3,%r14
  jne    L157
  mov    0x8(%rsp),%rax
  movzbl 0x3c(%rsp),%esi
  mov    %r13d,%edi
  mov    $0x1,%r13d
  movzbl 0x4(%rax),%eax
  mov    %r15b,0x2(%rbp)
  mov    %esi,%r14d
  mov    %al,0x3f(%rsp)
  call   <bd@plt>
  mov    %al,0x3(%rbp)
  movzbl %al,%r15d
  lea    0x3f(%rsp),%rax
  mov    %rax,0x8(%rsp)
L4:
  movzbl (%r12,%r13,1),%esi
  mov    %r15d,%edi
  call   <bd@plt>
  mov    0x8(%rsp),%rcx
  mov    %al,(%rcx,%r13,1)
  add    $0x1,%r13
  cmp    $0x5,%r13
  jne    L4
  mov    (%rsp),%rax
  lea    0x40(%rsp),%rdi
  movb   $0x0,(%rax)
  xor    %eax,%eax
L56:
  movzbl (%rdi,%rax,1),%edx
  mov    (%rsp),%rcx
  xor    %r14d,%edx
  mov    %dl,0x1(%rcx,%rax,1)
  add    $0x1,%rax
  cmp    $0x4,%rax
  je     L177
  movzbl (%rbx,%rax,1),%r14d
  jmp    L56
  nopw   0x0(%rax,%rax,1)
L177:
  movslq 0x24(%rsp),%rbx
  mov    0x18(%rsp),%r14
  lea    0x44(%rsp),%r12
  mov    %rbp,%rsi
  mov    %r12,%rdx
  shl    $0x2,%rbx
  lea    (%r14,%rbx,1),%rdi
  call   <modprod@plt>
  lea    0x4(%r14,%rbx,1),%rsi
  lea    -0x4(%r14,%rbx,1),%rcx
  xor    %eax,%eax
L90:
  movzbl (%rcx,%rax,1),%edx
  xor    (%r12,%rax,1),%dl
  mov    %dl,(%rsi,%rax,1)
  add    $0x1,%rax
  cmp    $0x4,%rax
  jne    L90
  jmp    L100
  nopl   0x0(%rax,%rax,1)
L2:
  lea    -0x1(%r14),%r9d
  jmp    L40
L84:
  call   <__stack_chk_fail@plt>
```

assistant: ```c
void longdivision(unsigned char a[5], unsigned char b[5], unsigned char dest[5], unsigned char quo[4], unsigned char x[6][4], int round) {
  int i, j;
  int index_a;
  int index_b;
  unsigned char inv;
  unsigned char prod[4] = {0, 0, 0, 0};
  unsigned char temp[4] = {0, 0, 0, 0};
  unsigned char tempx[4] = {0, 0, 0, 0};
  if (a[0] == 1) {
    quo[0] = 0;
    quo[1] = 0;
    inv = miLookup(b[1]);
    for (i = 0; i < 3; i++) {
      prod[i] = bd(inv, b[i + 2]);
    }
    prod[3] = a[4];
    quo[2] = inv;
    inv = bd(inv, prod[0]);
    quo[3] = inv;
    for (i = 0; i < 4; i++) {
      temp[i] = bd(inv, b[i + 1]);
    }
    dest[0] = 0x0;
    for (i = 0; i < 4; i++) {
      dest[i + 1] = prod[i] ^ temp[i];
    }
    modprod(x[round], quo, tempx);
    for (i = 0; i < 4; i++) {
      x[round + 1][i] = x[round - 1][i] ^ tempx[i];
    }
  } else {
    quo[0] = 0;
    quo[1] = 0;
    for (index_a = 0; index_a < 5; index_a++) {
      if (a[index_a] != 0) {
        break;
      }
    }
    for (index_b = 0; index_b < 5; index_b++) {
      if (b[index_b] != 0x0) {
        break;
      }
    }
    inv = miLookup(b[index_b]);
    quo[2] = bd(inv, a[index_a]);
    j = 0;
    for (i = index_a - 1; i < 4 - index_b + index_a; i++, j++) {
      prod[i] = bd(quo[2], b[index_b + j]);
    }
    j = 0;
    for (i = index_a - 1; i < 4 - index_b + index_a; i++, j++) {
      temp[i] = a[index_a + j] ^ prod[i];
    }
    temp[3] = a[4];
    quo[3] = bd(inv, temp[index_a]);
    for (i = 0; i < 4; i++) {
      prod[i] = bd(quo[3], b[i + 1]);
    }
    dest[0] = 0x0;
    for (i = 0; i < 4; i++) {
      dest[i + 1] = prod[i] ^ temp[i];
    }
    modprod(x[round], quo, tempx);
    for (i = 0; i < 4; i++) {
      x[round + 1][i] = x[round - 1][i] ^ tempx[i];
    }
  }
}
```