user: 下面的汇编指令对应的C源代码是什么:

```asm
<imcd_float24_decode>:
  endbr64
  push   %r12
  xor    %eax,%eax
  push   %rbp
  push   %rbx
  mov    %esi,%ebx
  cmp    $0x2,%esi
  jle    L78
  mov    %rdx,%rsi
  mov    %ecx,%ebp
  xor    %r10d,%r10d
  mov    $0x40,%r12d
  jmp    L70
  nopl   (%rax)
L72:
  cmp    $0x7f,%edx
  je     L54
  lea    0x40(%rdx),%r8d
  test   %edx,%edx
  je     L59
L96:
  mov    %r8d,%eax
  shl    $0x7,%r8d
  sar    %eax
  movzbl %r8b,%r8d
  or     %eax,%r11d
  mov    %r9d,%eax
  shl    $0x7,%r9d
  sar    %eax
  movzbl %r9b,%r9d
  and    $0x7f,%eax
  or     %eax,%r8d
  mov    %ecx,%eax
  shl    $0x7,%ecx
  sar    %eax
  movzbl %cl,%ecx
  and    $0x7f,%eax
  or     %r9d,%eax
L44:
  mov    %ecx,(%rsi)
  add    $0x3,%r10d
  add    $0x10,%rsi
  mov    %eax,-0xc(%rsi)
  mov    %r8d,-0x8(%rsi)
  mov    %r11d,-0x4(%rsi)
  cmp    %r10d,%ebx
  jle    L63
L70:
  mov    (%rdi),%edx
  mov    0x4(%rdi),%r9d
  add    $0xc,%rdi
  mov    -0x4(%rdi),%ecx
  cmp    $0x3c,%bpl
  jne    L69
  mov    %edx,%eax
  mov    %ecx,%edx
  mov    %eax,%ecx
L69:
  mov    %r9d,%eax
  mov    %edx,%r11d
  and    $0x7f,%edx
  shl    $0x8,%eax
  mov    %edx,%r8d
  and    $0x80,%r11d
  or     %ecx,%eax
  or     %eax,%r8d
  jne    L72
  xor    %ecx,%ecx
  xor    %eax,%eax
  jmp    L44
  nopw   0x0(%rax,%rax,1)
L63:
  movslq %ebx,%rax
  sar    $0x1f,%ebx
  imul   $0x55555556,%rax,%rax
  shr    $0x20,%rax
  sub    %ebx,%eax
  lea    (%rax,%rax,2),%eax
L78:
  pop    %rbx
  pop    %rbp
  pop    %r12
  ret
  nopl   0x0(%rax,%rax,1)
L54:
  or     $0x7f,%r11d
  xor    %ecx,%ecx
  mov    $0x80,%r8d
  test   %eax,%eax
  je     L44
  xor    %eax,%eax
  mov    $0xc0,%r8d
  jmp    L44
  nopl   0x0(%rax)
L59:
  mov    $0xffffffff,%edx
  nopl   (%rax)
L39:
  add    %eax,%eax
  add    $0x1,%edx
  test   $0x10000,%eax
  je     L39
  movzbl %al,%ecx
  mov    %r12d,%r8d
  movzbl %ah,%eax
  mov    %eax,%r9d
  sub    %edx,%r8d
  jmp    L96
```

assistant: ```c
ssize_t imcd_float24_decode(const uint8_t *src, const ssize_t srcsize, uint8_t *dst, const char byteorder) {
  ssize_t i;
  uint8_t s0, s1, s2, f0, f1, f2, f3;
  uint8_t sign = 0;
  uint8_t exponent = 0;
  uint32_t mantissa = 0;
  if (srcsize < 3) {
    return 0;
  }
  for (i = 0; i < srcsize; i += 3) {
    if (byteorder == '<') {
      s2 = *src++;
      s1 = *src++;
      s0 = *src++;
    } else {
      s0 = *src++;
      s1 = *src++;
      s2 = *src++;
    }
    sign = s0 & 0x80;
    exponent = s0 & 0x7F;
    mantissa = s1;
    mantissa <<= 8;
    mantissa |= s2;
    f0 = sign;
    if ((exponent == 0) & (mantissa == 0)) {
      f1 = 0;
      f2 = 0;
      f3 = 0;
    } else if (exponent == 0x7F) {
      f0 |= 0x7F;
      f1 = (mantissa == 0) ? 0x80 : 0xC0;
      f2 = 0;
      f3 = 0;
    } else {
      if (exponent == 0) {
        int shift = -1;
        do {
          shift++;
          mantissa <<= 1;
        } while ((mantissa & 0x10000) == 0);
        s2 = mantissa & 0xFF;
        s1 = (mantissa >> 8) & 0xFF;
        exponent = exponent - 63 + 127 - shift;
      } else {
        exponent = exponent - 63 + 127;
      }
      f0 |= exponent >> 1;
      f1 = ((exponent & 0x01) << 7) | ((s1 & 0xFE) >> 1);
      f2 = ((s1 & 0x01) << 7) | ((s2 & 0xFE) >> 1);
      f3 = (s2 & 0x01) << 7;
    }
    *dst++ = f3;
    *dst++ = f2;
    *dst++ = f1;
    *dst++ = f0;
  }
  return (srcsize / 3) * 3;
}
```