user: What would the C source look like for the assembly code provided here?

```asm
<BRBase58DecodeEx>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbx
  sub    $0x458,%rsp
  mov    %rdi,-0x458(%rbp)
  mov    %rsi,-0x468(%rbp)
  mov    %rdx,%r12
  mov    %rcx,%r13
  mov    %fs:0x28,%rax
  mov    %rax,-0x38(%rbp)
  xor    %eax,%eax
  lea    -0x440(%rbp),%rdi
  mov    $0x400,%edx
  mov    $0xffffffff,%esi
  call   <memset@plt>
  mov    $0x0,%ebx
L75:
  mov    %r13,%rdi
  call   <strlen@plt>
  cmp    %ebx,%eax
  jle    L89
  movsbq 0x0(%r13,%rbx,1),%rax
  mov    %ebx,-0x440(%rbp,%rax,4)
  add    $0x1,%rbx
  jmp    L75
L89:
  mov    $0x0,%r13d
  test   %r12,%r12
  jne    L51
  lea    -0x444(%rbp),%rbx
  mov    $0x0,%edx
  mov    $0x0,%esi
  mov    %rbx,%rdi
  call   <memset@plt>
  mov    $0x0,%r13d
  movl   $0x0,-0x474(%rbp)
  movq   $0x0,-0x460(%rbp)
L4:
  mov    $0x1,%eax
  mov    $0x0,%r12d
  cmpl   $0x0,(%rbx)
  jne    L8
L129:
  mov    %eax,%r12d
  add    $0x1,%rax
  cmpl   $0x0,-0x4(%rbx,%rax,4)
  je     L129
L8:
  movslq %r13d,%rax
  mov    %rax,-0x470(%rbp)
  movslq %r12d,%r15
  mov    -0x460(%rbp),%r14
  add    %rax,%r14
  sub    %r15,%r14
  cmp    -0x468(%rbp),%r14
  setbe  %al
  mov    -0x458(%rbp),%rdi
  test   %rdi,%rdi
  je     L188
  test   %al,%al
  je     L188
  test   %r13d,%r13d
  jg     L63
L97:
  mov    -0x474(%rbp),%edx
  sub    %r12d,%edx
  lea    (%rbx,%r15,4),%rsi
  mov    -0x458(%rbp),%rax
  mov    -0x470(%rbp),%rdi
  lea    (%rax,%rdi,4),%rdi
  call   <memcpy@plt>
  jmp    L113
L218:
  add    $0x1,%r12
  add    $0x1,%r13d
L51:
  movsbq (%r12),%rax
  cmpl   $0x0,-0x440(%rbp,%rax,4)
  je     L218
  mov    %r12,%rdi
  call   <strlen@plt>
  imul   $0x2dd,%eax,%r15d
  movslq %r15d,%r14
  imul   $0x10624dd3,%r14,%r14
  sar    $0x26,%r14
  mov    %r15d,%eax
  sar    $0x1f,%eax
  sub    %eax,%r14d
  lea    0x1(%r14),%edx
  movslq %edx,%rax
  shl    $0x2,%rax
  mov    %rax,-0x460(%rbp)
  add    $0xf,%rax
  mov    %rax,%rsi
  and    $0xfffffffffffffff0,%rsi
  and    $0xfffffffffffff000,%rax
  mov    %rsp,%rcx
  sub    %rax,%rcx
L161:
  cmp    %rcx,%rsp
  je     L165
  sub    $0x1000,%rsp
  orq    $0x0,0xff8(%rsp)
  jmp    L161
L9:
  add    $0x1,%r12
L179:
  movzbl (%r12),%eax
  test   %al,%al
  je     L4
  movsbq %al,%rax
  mov    -0x440(%rbp,%rax,4),%edx
  cmp    $0xffffffff,%edx
  je     L103
  cmp    $0xfffffc19,%r15d
  jl     L9
  movslq %r14d,%rcx
L111:
  imul   $0x3a,(%rbx,%rcx,4),%eax
  add    %edx,%eax
  mov    %eax,%esi
  sar    $0x1f,%esi
  shr    $0x18,%esi
  lea    (%rax,%rsi,1),%edx
  movzbl %dl,%edx
  sub    %esi,%edx
  mov    %edx,(%rbx,%rcx,4)
  lea    0xff(%rax),%edx
  test   %eax,%eax
  cmovns %eax,%edx
  sar    $0x8,%edx
  sub    $0x1,%rcx
  test   %ecx,%ecx
  jns    L111
  jmp    L9
L63:
  mov    %r13d,%edx
  mov    $0x0,%esi
  call   <memset@plt>
  jmp    L97
L188:
  cmpq   $0x0,-0x458(%rbp)
  je     L113
  test   %al,%al
  mov    $0x0,%eax
  cmove  %rax,%r14
L113:
  mov    -0x38(%rbp),%rax
  sub    %fs:0x28,%rax
  jne    L133
  mov    %r14,%rax
  lea    -0x28(%rbp),%rsp
  pop    %rbx
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  pop    %rbp
  ret
L103:
  mov    $0x0,%r14d
  jmp    L113
L165:
  mov    %rsi,%rax
  and    $0xfff,%eax
  sub    %rax,%rsp
  test   %rax,%rax
  je     L162
  orq    $0x0,-0x8(%rsp,%rax,1)
L162:
  mov    %rsp,%rdi
  mov    %rdi,%rbx
  lea    0x0(,%rdx,4),%eax
  mov    %eax,-0x474(%rbp)
  mov    %eax,%edx
  mov    $0x0,%esi
  call   <memset@plt>
  jmp    L179
L133:
  call   <__stack_chk_fail@plt>
```

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;
}
```