user: 请显示与下面列出的汇编代码相匹配的C语言实现:

```asm
<sam3Base32Decode>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  sub    $0x28,%rsp
  mov    %edx,%ebp
  mov    %fs:0x28,%rax
  mov    %rax,0x18(%rsp)
  xor    %eax,%eax
  test   %rsi,%rsi
  setne  %dl
  mov    %ebp,%eax
  not    %eax
  shr    $0x1f,%eax
  test   %al,%dl
  je     L119
  mov    %rdi,%rbx
  mov    %rsi,%r15
  test   %rdi,%rdi
  je     L119
  test   %ebp,%ebp
  jle    L53
  movl   $0x0,0xc(%rsp)
  lea    0x10(%rsp),%r12
  lea    D19(%rip),%r13
  jmp    L20
  movzbl 0x4(%r15),%eax
  mov    %eax,%edx
  and    $0x1f,%edx
  mov    %dl,0x17(%rsp)
  shr    $0x5,%al
  mov    %al,0x16(%rsp)
  movzbl 0x3(%r15),%edx
  movzbl %dl,%eax
  lea    0x0(,%rax,8),%ecx
  and    $0x18,%ecx
  or     %cl,0x16(%rsp)
  sar    $0x2,%eax
  and    $0x1f,%eax
  mov    %al,0x15(%rsp)
  shr    $0x7,%dl
  mov    %dl,0x14(%rsp)
  movzbl 0x2(%r15),%eax
  lea    (%rax,%rax,1),%edx
  and    $0x1e,%edx
  or     %dl,0x14(%rsp)
  shr    $0x4,%al
  mov    %al,0x13(%rsp)
  movzbl 0x1(%r15),%edx
  movzbl %dl,%eax
  mov    %eax,%ecx
  shl    $0x4,%ecx
  and    $0x10,%ecx
  or     %cl,0x13(%rsp)
  sar    %eax
  and    $0x1f,%eax
  mov    %al,0x12(%rsp)
  shr    $0x6,%dl
  mov    %dl,0x11(%rsp)
  movzbl (%r15),%eax
  lea    0x0(,%rax,4),%edx
  and    $0x1c,%edx
  or     %dl,0x11(%rsp)
  shr    $0x3,%al
  mov    %al,0x10(%rsp)
L68:
  movslq %r14d,%rax
  add    %rax,%r15
  mov    %ebp,%ecx
  sub    %r14d,%ecx
  cmp    $0x3,%ebp
  je     L131
  jg     L113
  cmp    $0x1,%ebp
  je     L24
  cmp    $0x2,%ebp
  jne    L126
L77:
  movb   $0x20,0x14(%rsp)
L131:
  movb   $0x20,0x16(%rsp)
  movb   $0x20,0x15(%rsp)
  jmp    L18
L113:
  cmp    $0x4,%ebp
  jne    L126
L18:
  movb   $0x20,0x17(%rsp)
L126:
  mov    $0x0,%eax
L149:
  movzbl (%rax,%r12,1),%edx
  movzbl 0x0(%r13,%rdx,1),%edx
  mov    %dl,(%rbx,%rax,1)
  add    $0x1,%rax
  cmp    $0x8,%rax
  jne    L149
  add    $0x8,%rbx
  addl   $0x8,0xc(%rsp)
  test   %ecx,%ecx
  jle    L83
  mov    %ecx,%ebp
L20:
  mov    $0x5,%r14d
  cmp    %r14d,%ebp
  cmovle %ebp,%r14d
  mov    $0x8,%edx
  mov    $0x0,%esi
  mov    %r12,%rdi
  call   <memset@plt>
  cmp    $0x5,%r14d
  ja     L68
  mov    %r14d,%eax
  lea    D4(%rip),%rsi
  movslq (%rsi,%rax,4),%rax
  add    %rsi,%rax
  notrack jmp *%rax
L24:
  movb   $0x20,0x13(%rsp)
  movb   $0x20,0x12(%rsp)
  jmp    L77
L53:
  movl   $0x0,0xc(%rsp)
L83:
  movb   $0x0,(%rbx)
L71:
  mov    0x18(%rsp),%rax
  sub    %fs:0x28,%rax
  jne    L89
  mov    0xc(%rsp),%eax
  add    $0x28,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
L119:
  movl   $0xffffffff,0xc(%rsp)
  jmp    L71
L89:
  call   <__stack_chk_fail@plt>
```

tool_calls: name: read_data
arguments: data_label: D19
data_type: string

tool: D19: abcdefghijklmnopqrstuvwxyz234567=

assistant: ```c
int sam3Base32Decode(char *dest, const void *srcbuf, int srcsize) {
  if (dest != NULL && srcbuf != NULL && srcsize >= 0) {
    static const char *const b32chars = "abcdefghijklmnopqrstuvwxyz234567=";
    const unsigned char *src = (const unsigned char *)srcbuf;
    int destsize = 0;
    while (srcsize > 0) {
      int blksize = (srcsize < 5 ? srcsize : 5);
      unsigned char n[8];
      memset(n, 0, sizeof(n));
      switch (blksize) {
      case 5:
        n[7] = (src[4] & 0x1f);
        n[6] = ((src[4] & 0xe0) >> 5);
      case 4:
        n[6] |= ((src[3] & 0x03) << 3);
        n[5] = ((src[3] & 0x7c) >> 2);
        n[4] = ((src[3] & 0x80) >> 7);
      case 3:
        n[4] |= ((src[2] & 0x0f) << 1);
        n[3] = ((src[2] & 0xf0) >> 4);
      case 2:
        n[3] |= ((src[1] & 0x01) << 4);
        n[2] = ((src[1] & 0x3e) >> 1);
        n[1] = ((src[1] & 0xc0) >> 6);
      case 1:
        n[1] |= ((src[0] & 0x07) << 2);
        n[0] = ((src[0] & 0xf8) >> 3);
        break;
      }
      src += blksize;
      srcsize -= blksize;
      switch (blksize) {
      case 1:
        n[2] = n[3] = 32;
      case 2:
        n[4] = 32;
      case 3:
        n[5] = n[6] = 32;
      case 4:
        n[7] = 32;
      case 5:
        break;
      }
      for (int f = 0; f < 8; ++f)
        *dest++ = b32chars[n[f]];
      destsize += 8;
    }
    *dest++ = 0;
    return destsize;
  }
  return -1;
}
```