mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2025-11-04 05:17:07 +00:00
e5d8abe4f1
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217974 91177308-0d34-0410-b5e6-96231b3b80d8
122 lines
3.4 KiB
C++
122 lines
3.4 KiB
C++
//===- llvm/Support/LEB128.h - [SU]LEB128 utility functions -----*- C++ -*-===//
|
|
//
|
|
// The LLVM Compiler Infrastructure
|
|
//
|
|
// This file is distributed under the University of Illinois Open Source
|
|
// License. See LICENSE.TXT for details.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// This file declares some utility functions for encoding SLEB128 and
|
|
// ULEB128 values.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#ifndef LLVM_SUPPORT_LEB128_H
|
|
#define LLVM_SUPPORT_LEB128_H
|
|
|
|
#include "llvm/Support/raw_ostream.h"
|
|
|
|
namespace llvm {
|
|
|
|
/// Utility function to encode a SLEB128 value to an output stream.
|
|
inline void encodeSLEB128(int64_t Value, raw_ostream &OS) {
|
|
bool More;
|
|
do {
|
|
uint8_t Byte = Value & 0x7f;
|
|
// NOTE: this assumes that this signed shift is an arithmetic right shift.
|
|
Value >>= 7;
|
|
More = !((((Value == 0 ) && ((Byte & 0x40) == 0)) ||
|
|
((Value == -1) && ((Byte & 0x40) != 0))));
|
|
if (More)
|
|
Byte |= 0x80; // Mark this byte to show that more bytes will follow.
|
|
OS << char(Byte);
|
|
} while (More);
|
|
}
|
|
|
|
/// Utility function to encode a ULEB128 value to an output stream.
|
|
inline void encodeULEB128(uint64_t Value, raw_ostream &OS,
|
|
unsigned Padding = 0) {
|
|
do {
|
|
uint8_t Byte = Value & 0x7f;
|
|
Value >>= 7;
|
|
if (Value != 0 || Padding != 0)
|
|
Byte |= 0x80; // Mark this byte to show that more bytes will follow.
|
|
OS << char(Byte);
|
|
} while (Value != 0);
|
|
|
|
// Pad with 0x80 and emit a null byte at the end.
|
|
if (Padding != 0) {
|
|
for (; Padding != 1; --Padding)
|
|
OS << '\x80';
|
|
OS << '\x00';
|
|
}
|
|
}
|
|
|
|
/// Utility function to encode a ULEB128 value to a buffer. Returns
|
|
/// the length in bytes of the encoded value.
|
|
inline unsigned encodeULEB128(uint64_t Value, uint8_t *p,
|
|
unsigned Padding = 0) {
|
|
uint8_t *orig_p = p;
|
|
do {
|
|
uint8_t Byte = Value & 0x7f;
|
|
Value >>= 7;
|
|
if (Value != 0 || Padding != 0)
|
|
Byte |= 0x80; // Mark this byte to show that more bytes will follow.
|
|
*p++ = Byte;
|
|
} while (Value != 0);
|
|
|
|
// Pad with 0x80 and emit a null byte at the end.
|
|
if (Padding != 0) {
|
|
for (; Padding != 1; --Padding)
|
|
*p++ = '\x80';
|
|
*p++ = '\x00';
|
|
}
|
|
return (unsigned)(p - orig_p);
|
|
}
|
|
|
|
|
|
/// Utility function to decode a ULEB128 value.
|
|
inline uint64_t decodeULEB128(const uint8_t *p, unsigned *n = nullptr) {
|
|
const uint8_t *orig_p = p;
|
|
uint64_t Value = 0;
|
|
unsigned Shift = 0;
|
|
do {
|
|
Value += uint64_t(*p & 0x7f) << Shift;
|
|
Shift += 7;
|
|
} while (*p++ >= 128);
|
|
if (n)
|
|
*n = (unsigned)(p - orig_p);
|
|
return Value;
|
|
}
|
|
|
|
/// Utility function to decode a SLEB128 value.
|
|
inline int64_t decodeSLEB128(const uint8_t *p, unsigned *n = nullptr) {
|
|
const uint8_t *orig_p = p;
|
|
int64_t Value = 0;
|
|
unsigned Shift = 0;
|
|
uint8_t Byte;
|
|
do {
|
|
Byte = *p++;
|
|
Value |= ((Byte & 0x7f) << Shift);
|
|
Shift += 7;
|
|
} while (Byte >= 128);
|
|
// Sign extend negative numbers.
|
|
if (Byte & 0x40)
|
|
Value |= (-1ULL) << Shift;
|
|
if (n)
|
|
*n = (unsigned)(p - orig_p);
|
|
return Value;
|
|
}
|
|
|
|
|
|
/// Utility function to get the size of the ULEB128-encoded value.
|
|
extern unsigned getULEB128Size(uint64_t Value);
|
|
|
|
/// Utility function to get the size of the SLEB128-encoded value.
|
|
extern unsigned getSLEB128Size(int64_t Value);
|
|
|
|
} // namespace llvm
|
|
|
|
#endif // LLVM_SYSTEM_LEB128_H
|