user: Demonstrate the C code that generates the assembly output below:

```asm
<BRBase58DecodeEx>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  push   %r15
  push   %r14
  push   %r12
  push   %rbx
  sub    $0x480,%rsp
  mov    %rdi,-0x478(%rbp)
  mov    %rsi,-0x480(%rbp)
  mov    %rdx,-0x488(%rbp)
  mov    %rcx,-0x490(%rbp)
  mov    %fs:0x28,%rax
  mov    %rax,-0x28(%rbp)
  xor    %eax,%eax
  mov    %rsp,%rax
  mov    %rax,%r12
  lea    -0x430(%rbp),%rax
  mov    $0x400,%edx
  mov    $0xffffffff,%esi
  mov    %rax,%rdi
  call   <memset@plt>
  movl   $0x0,-0x464(%rbp)
  movl   $0x0,-0x460(%rbp)
  jmp    L228
L86:
  mov    -0x464(%rbp),%eax
  lea    0x1(%rax),%edx
  mov    %edx,-0x464(%rbp)
  mov    -0x460(%rbp),%edx
  movslq %edx,%rcx
  mov    -0x490(%rbp),%rdx
  add    %rcx,%rdx
  movzbl (%rdx),%edx
  movsbl %dl,%edx
  movslq %edx,%rdx
  mov    %eax,-0x430(%rbp,%rdx,4)
  addl   $0x1,-0x460(%rbp)
L228:
  mov    -0x490(%rbp),%rax
  mov    %rax,%rdi
  call   <strlen@plt>
  cmp    %eax,-0x460(%rbp)
  jl     L86
  movl   $0x0,-0x45c(%rbp)
  jmp    L26
L149:
  addq   $0x1,-0x488(%rbp)
  addl   $0x1,-0x45c(%rbp)
L26:
  cmpq   $0x0,-0x488(%rbp)
  je     L134
  mov    -0x488(%rbp),%rax
  movzbl (%rax),%eax
  movsbl %al,%eax
  cltq
  mov    -0x430(%rbp,%rax,4),%eax
  test   %eax,%eax
  je     L149
L134:
  cmpq   $0x0,-0x488(%rbp)
  je     L17
  mov    -0x488(%rbp),%rax
  mov    %rax,%rdi
  call   <strlen@plt>
  imul   $0x2dd,%eax,%eax
  movslq %eax,%rdx
  imul   $0x10624dd3,%rdx,%rdx
  shr    $0x20,%rdx
  sar    $0x6,%edx
  sar    $0x1f,%eax
  mov    %eax,%ecx
  mov    %edx,%eax
  sub    %ecx,%eax
  add    $0x1,%eax
  jmp    L79
L17:
  mov    $0x0,%eax
L79:
  mov    %eax,-0x44c(%rbp)
  mov    -0x44c(%rbp),%ebx
  movslq %ebx,%rax
  sub    $0x1,%rax
  mov    %rax,-0x448(%rbp)
  movslq %ebx,%rax
  mov    %rax,-0x4a0(%rbp)
  movq   $0x0,-0x498(%rbp)
  movslq %ebx,%rax
  mov    %rax,%r14
  mov    $0x0,%r15d
  movslq %ebx,%rax
  lea    0x0(,%rax,4),%rdx
  mov    $0x10,%eax
  sub    $0x1,%rax
  add    %rdx,%rax
  mov    $0x10,%esi
  mov    $0x0,%edx
  div    %rsi
  imul   $0x10,%rax,%rax
  mov    %rax,%rcx
  and    $0xfffffffffffff000,%rcx
  mov    %rsp,%rdx
  sub    %rcx,%rdx
L29:
  cmp    %rdx,%rsp
  je     L201
  sub    $0x1000,%rsp
  orq    $0x0,0xff8(%rsp)
  jmp    L29
L201:
  mov    %rax,%rdx
  and    $0xfff,%edx
  sub    %rdx,%rsp
  mov    %rax,%rdx
  and    $0xfff,%edx
  test   %rdx,%rdx
  je     L2
  and    $0xfff,%eax
  sub    $0x8,%rax
  add    %rsp,%rax
  orq    $0x0,(%rax)
L2:
  mov    %rsp,%rax
  add    $0x3,%rax
  shr    $0x2,%rax
  shl    $0x2,%rax
  mov    %rax,-0x440(%rbp)
  movslq %ebx,%rax
  shl    $0x2,%eax
  mov    %eax,%edx
  mov    -0x440(%rbp),%rax
  mov    $0x0,%esi
  mov    %rax,%rdi
  call   <memset@plt>
  jmp    L80
L145:
  mov    -0x488(%rbp),%rax
  movzbl (%rax),%eax
  movsbl %al,%eax
  cltq
  mov    -0x430(%rbp,%rax,4),%eax
  mov    %eax,-0x458(%rbp)
  cmpl   $0xffffffff,-0x458(%rbp)
  jne    L100
  mov    $0x0,%eax
  jmp    L141
L100:
  mov    -0x44c(%rbp),%eax
  sub    $0x1,%eax
  mov    %eax,-0x454(%rbp)
  jmp    L203
L246:
  mov    -0x440(%rbp),%rax
  mov    -0x454(%rbp),%edx
  movslq %edx,%rdx
  mov    (%rax,%rdx,4),%eax
  imul   $0x3a,%eax,%eax
  add    %eax,-0x458(%rbp)
  mov    -0x458(%rbp),%eax
  cltd
  shr    $0x18,%edx
  add    %edx,%eax
  movzbl %al,%eax
  sub    %edx,%eax
  mov    %eax,%ecx
  mov    -0x440(%rbp),%rax
  mov    -0x454(%rbp),%edx
  movslq %edx,%rdx
  mov    %ecx,(%rax,%rdx,4)
  mov    -0x458(%rbp),%eax
  lea    0xff(%rax),%edx
  test   %eax,%eax
  cmovs  %edx,%eax
  sar    $0x8,%eax
  mov    %eax,-0x458(%rbp)
  subl   $0x1,-0x454(%rbp)
L203:
  cmpl   $0x0,-0x454(%rbp)
  jns    L246
  addq   $0x1,-0x488(%rbp)
L80:
  cmpq   $0x0,-0x488(%rbp)
  je     L180
  mov    -0x488(%rbp),%rax
  movzbl (%rax),%eax
  test   %al,%al
  jne    L145
L180:
  movl   $0x0,-0x450(%rbp)
  jmp    L199
L175:
  addl   $0x1,-0x450(%rbp)
L199:
  mov    -0x440(%rbp),%rax
  mov    -0x450(%rbp),%edx
  movslq %edx,%rdx
  mov    (%rax,%rdx,4),%eax
  test   %eax,%eax
  je     L175
  mov    -0x45c(%rbp),%eax
  movslq %eax,%rdx
  movslq %ebx,%rax
  shl    $0x2,%rax
  add    %rax,%rdx
  mov    -0x450(%rbp),%eax
  movslq %eax,%rcx
  mov    %rdx,%rax
  sub    %rcx,%rax
  mov    %rax,-0x438(%rbp)
  cmpq   $0x0,-0x478(%rbp)
  je     L218
  mov    -0x438(%rbp),%rax
  cmp    -0x480(%rbp),%rax
  ja     L218
  cmpl   $0x0,-0x45c(%rbp)
  jle    L61
  mov    -0x45c(%rbp),%edx
  mov    -0x478(%rbp),%rax
  mov    $0x0,%esi
  mov    %rax,%rdi
  call   <memset@plt>
L61:
  movslq %ebx,%rax
  shl    $0x2,%eax
  mov    -0x450(%rbp),%edx
  sub    %edx,%eax
  mov    %eax,%edx
  mov    -0x450(%rbp),%eax
  cltq
  lea    0x0(,%rax,4),%rcx
  mov    -0x440(%rbp),%rax
  add    %rax,%rcx
  mov    -0x45c(%rbp),%eax
  cltq
  lea    0x0(,%rax,4),%rsi
  mov    -0x478(%rbp),%rax
  add    %rsi,%rax
  mov    %rcx,%rsi
  mov    %rax,%rdi
  call   <memcpy@plt>
L218:
  cmpq   $0x0,-0x478(%rbp)
  je     L19
  mov    -0x438(%rbp),%rax
  cmp    -0x480(%rbp),%rax
  ja     L254
L19:
  mov    -0x438(%rbp),%rax
  jmp    L141
L254:
  mov    $0x0,%eax
L141:
  mov    %r12,%rsp
  mov    -0x28(%rbp),%rdx
  sub    %fs:0x28,%rdx
  je     L131
  call   <__stack_chk_fail@plt>
L131:
  lea    -0x20(%rbp),%rsp
  pop    %rbx
  pop    %r12
  pop    %r14
  pop    %r15
  pop    %rbp
  ret
```

assistant: ```c
size_t BRBase58DecodeEx(uint8_t *data, size_t dataLen, const char *str, const char *alphabet) {
  int reverseLookup[256];
  memset(&reverseLookup[0], -1, sizeof(reverseLookup));
  int map_num = 0;
  for (int i = 0; i < strlen(alphabet); i++) {
    reverseLookup[alphabet[i]] = map_num++;
  }
  int zcount = 0;
  while (str && reverseLookup[*str] == 0)
    str++, zcount++;
  int bufSize = (str) ? (int)(strlen(str) * 733 / 1000 + 1) : 0;
  uint8_t buf[bufSize];
  memset(buf, 0, sizeof(buf));
  while (str && *str) {
    int carry = reverseLookup[*str];
    if (carry == -1)
      return 0;
    for (int i = bufSize - 1; i >= 0; i--) {
      carry += 58 * buf[i];
      buf[i] = carry % 256;
      carry /= 256;
    }
    str++;
  }
  int i = 0;
  while (buf[i] == 0) {
    i++;
  }
  size_t len = zcount + sizeof(buf) - i;
  if (data && len <= dataLen) {
    if (zcount > 0)
      memset(data, 0, zcount);
    memcpy(&data[zcount], &buf[i], sizeof(buf) - i);
  }
  return (!data || len <= dataLen) ? len : 0;
}
```