mirror of
https://github.com/libretro/scummvm.git
synced 2024-12-22 18:02:05 +00:00
66e9d4f5e8
svn-id: r30664
221 lines
6.2 KiB
C
221 lines
6.2 KiB
C
/* ScummVM - Graphic Adventure Engine
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*
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* ScummVM is the legal property of its developers, whose names
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* are too numerous to list here. Please refer to the COPYRIGHT
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* file distributed with this source distribution.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*
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* $URL$
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* $Id$
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*
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*/
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#ifndef COMMON_ENDIAN_H
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#define COMMON_ENDIAN_H
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#include "common/scummsys.h"
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//
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// Endian conversion functions, macros etc., follow from here!
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//
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/**
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* Swap the bytes in a 32 bit word in order to convert LE encoded data to BE
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* and vice versa.
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*/
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FORCEINLINE uint32 SWAP_BYTES_32(uint32 a) {
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return ((a >> 24) & 0x000000FF) |
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((a >> 8) & 0x0000FF00) |
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((a << 8) & 0x00FF0000) |
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((a << 24) & 0xFF000000);
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}
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/**
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* Swap the bytes in a 16 bit word in order to convert LE encoded data to BE
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* and vice versa.
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*/
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FORCEINLINE uint16 SWAP_BYTES_16(uint16 a) {
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return ((a >> 8) & 0x00FF) + ((a << 8) & 0xFF00);
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}
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/**
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* A wrapper macro used around four character constants, like 'DATA', to
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* ensure portability. Typical usage: MKID_BE('DATA').
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*
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* Why is this necessary? The C/C++ standard does not define the endianess to
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* be used for character constants. Hence if one uses multi-byte character
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* constants, a potential portability problem opens up.
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*
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* Fortunately, a semi-standard has been established: On almost all systems
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* and compilers, multi-byte character constants are encoded using the big
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* endian convention (probably in analogy to the encoding of string constants).
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* Still some systems differ. This is why we provide the MKID_BE macro. If
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* you wrap your four character constants with it, the result will always be
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* BE encoded, even on systems which differ from the default BE encoding.
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*
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* For the latter systems we provide the INVERSE_MKID override.
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*/
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#if defined(INVERSE_MKID)
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#define MKID_BE(a) ((uint32) \
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(((a) >> 24) & 0x000000FF) | \
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(((a) >> 8) & 0x0000FF00) | \
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(((a) << 8) & 0x00FF0000) | \
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(((a) << 24) & 0xFF000000))
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#else
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# define MKID_BE(a) ((uint32)(a))
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#endif
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#if defined(SCUMM_LITTLE_ENDIAN)
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#define READ_UINT16(a) READ_LE_UINT16(a)
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#define READ_UINT32(a) READ_LE_UINT32(a)
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#define WRITE_UINT16(a, v) WRITE_LE_UINT16(a, v)
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#define WRITE_UINT32(a, v) WRITE_LE_UINT32(a, v)
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#define FROM_LE_32(a) ((uint32)(a))
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#define FROM_LE_16(a) ((uint16)(a))
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#define FROM_BE_32(a) SWAP_BYTES_32(a)
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#define FROM_BE_16(a) SWAP_BYTES_16(a)
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#define TO_LE_32(a) ((uint32)(a))
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#define TO_LE_16(a) ((uint16)(a))
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#define TO_BE_32(a) SWAP_BYTES_32(a)
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#define TO_BE_16(a) SWAP_BYTES_16(a)
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#elif defined(SCUMM_BIG_ENDIAN)
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#define MKID(a) ((uint32)(a))
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#define MKID_BE(a) ((uint32)(a))
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#define READ_UINT16(a) READ_BE_UINT16(a)
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#define READ_UINT32(a) READ_BE_UINT32(a)
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#define WRITE_UINT16(a, v) WRITE_BE_UINT16(a, v)
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#define WRITE_UINT32(a, v) WRITE_BE_UINT32(a, v)
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#define FROM_LE_32(a) SWAP_BYTES_32(a)
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#define FROM_LE_16(a) SWAP_BYTES_16(a)
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#define FROM_BE_32(a) ((uint32)(a))
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#define FROM_BE_16(a) ((uint16)(a))
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#define TO_LE_32(a) SWAP_BYTES_32(a)
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#define TO_LE_16(a) SWAP_BYTES_16(a)
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#define TO_BE_32(a) ((uint32)(a))
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#define TO_BE_16(a) ((uint16)(a))
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#else
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#error No endianness defined
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#endif
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#if defined(SCUMM_NEED_ALIGNMENT) || !defined(SCUMM_LITTLE_ENDIAN)
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FORCEINLINE uint16 READ_LE_UINT16(const void *ptr) {
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const byte *b = (const byte *)ptr;
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return (b[1] << 8) + b[0];
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}
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FORCEINLINE uint32 READ_LE_UINT32(const void *ptr) {
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const byte *b = (const byte *)ptr;
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return (b[3] << 24) + (b[2] << 16) + (b[1] << 8) + (b[0]);
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}
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FORCEINLINE void WRITE_LE_UINT16(void *ptr, uint16 value) {
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byte *b = (byte *)ptr;
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b[0] = (byte)(value >> 0);
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b[1] = (byte)(value >> 8);
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}
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FORCEINLINE void WRITE_LE_UINT32(void *ptr, uint32 value) {
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byte *b = (byte *)ptr;
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b[0] = (byte)(value >> 0);
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b[1] = (byte)(value >> 8);
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b[2] = (byte)(value >> 16);
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b[3] = (byte)(value >> 24);
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}
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#else
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FORCEINLINE uint16 READ_LE_UINT16(const void *ptr) {
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return *(const uint16 *)(ptr);
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}
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FORCEINLINE uint32 READ_LE_UINT32(const void *ptr) {
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return *(const uint32 *)(ptr);
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}
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FORCEINLINE void WRITE_LE_UINT16(void *ptr, uint16 value) {
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*(uint16 *)(ptr) = value;
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}
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FORCEINLINE void WRITE_LE_UINT32(void *ptr, uint32 value) {
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*(uint32 *)(ptr) = value;
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}
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#endif
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#if defined(SCUMM_NEED_ALIGNMENT) || !defined(SCUMM_BIG_ENDIAN)
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FORCEINLINE uint16 READ_BE_UINT16(const void *ptr) {
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const byte *b = (const byte *)ptr;
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return (b[0] << 8) + b[1];
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}
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FORCEINLINE uint32 READ_BE_UINT32(const void *ptr) {
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const byte *b = (const byte*)ptr;
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return (b[0] << 24) + (b[1] << 16) + (b[2] << 8) + (b[3]);
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}
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FORCEINLINE void WRITE_BE_UINT16(void *ptr, uint16 value) {
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byte *b = (byte *)ptr;
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b[0] = (byte)(value >> 8);
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b[1] = (byte)(value >> 0);
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}
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FORCEINLINE void WRITE_BE_UINT32(void *ptr, uint32 value) {
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byte *b = (byte *)ptr;
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b[0] = (byte)(value >> 24);
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b[1] = (byte)(value >> 16);
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b[2] = (byte)(value >> 8);
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b[3] = (byte)(value >> 0);
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}
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#else
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FORCEINLINE uint16 READ_BE_UINT16(const void *ptr) {
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return *(const uint16 *)(ptr);
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}
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FORCEINLINE uint32 READ_BE_UINT32(const void *ptr) {
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return *(const uint32 *)(ptr);
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}
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FORCEINLINE void WRITE_BE_UINT16(void *ptr, uint16 value) {
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*(uint16 *)(ptr) = value;
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}
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FORCEINLINE void WRITE_BE_UINT32(void *ptr, uint32 value) {
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*(uint32 *)(ptr) = value;
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}
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#endif
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FORCEINLINE uint32 READ_LE_UINT24(const void *ptr) {
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const byte *b = (const byte *)ptr;
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return (b[2] << 16) + (b[1] << 8) + (b[0]);
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}
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FORCEINLINE uint32 READ_BE_UINT24(const void *ptr) {
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const byte *b = (const byte*)ptr;
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return (b[0] << 16) + (b[1] << 8) + (b[2]);
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}
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#endif
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