uc_stack.h

/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#ifndef ULTIMA8_USECODE_UCSTACK_H
#define ULTIMA8_USECODE_UCSTACK_H

#include "common/scummsys.h"

namespace Common {
class ReadStream;
class WriteStream;
}

namespace Ultima {
namespace Ultima8 {

// A little-endian stack for use with usecode
class BaseUCStack {
protected:
    uint8 *_buf;
    uint8 *_bufPtr;
    uint32 _size;
public:

    BaseUCStack(uint32 len, uint8 *b) : _buf(b), _size(len) {
        // stack grows downward, so start at the end of the buffer
        _bufPtr = _buf + _size;
    }
    virtual ~BaseUCStack() { }

    inline uint32 getSize() const {
        return _size;
    }

    inline uint32 stacksize() const {
        return _size - (_bufPtr - _buf);
    }

    inline void addSP(const int32 offset) {
        _bufPtr += offset;
    }

    inline unsigned int getSP() const {
        return static_cast<unsigned int>(_bufPtr - _buf);
    }

    inline void setSP(unsigned int pos) {
        _bufPtr = _buf + pos;
    }

    //
    // Push values to the stack
    //

    inline void push1(uint8 val) {
        _bufPtr--;
        _bufPtr[0] = val;
    }

    inline void push2(uint16 val) {
        _bufPtr -= 2;
        _bufPtr[0] = static_cast<uint8>(val     & 0xFF);
        _bufPtr[1] = static_cast<uint8>((val >> 8) & 0xFF);
    }
    inline void push4(uint32 val) {
        _bufPtr -= 4;
        _bufPtr[0] = static_cast<uint8>(val      & 0xFF);
        _bufPtr[1] = static_cast<uint8>((val >> 8)  & 0xFF);
        _bufPtr[2] = static_cast<uint8>((val >> 16) & 0xFF);
        _bufPtr[3] = static_cast<uint8>((val >> 24) & 0xFF);
    }
    // Push an arbitrary number of bytes of 0
    inline void push0(const uint32 count) {
        _bufPtr -= count;
        memset(_bufPtr, 0, count);
    }
    // Push an arbitrary number of bytes
    inline void push(const uint8 *in, const uint32 count) {
        _bufPtr -= count;
        memcpy(_bufPtr, in, count);
    }

    //
    // Pop values from the stack
    //

    inline uint16 pop2() {
        uint8 b0, b1;
        b0 = *_bufPtr++;
        b1 = *_bufPtr++;
        return (b0 | (b1 << 8));
    }
    inline uint32 pop4() {
        uint8 b0, b1, b2, b3;
        b0 = *_bufPtr++;
        b1 = *_bufPtr++;
        b2 = *_bufPtr++;
        b3 = *_bufPtr++;
        return (b0 | (b1 << 8) | (b2 << 16) | (b3 << 24));
    }
    inline void pop(uint8 *out, const uint32 count) {
        memcpy(out, _bufPtr, count);
        _bufPtr += count;
    }

    //
    // Access a value from a location in the stack
    //

    inline uint8 access1(const uint32 offset) const {
        return _buf[offset];
    }
    inline uint16 access2(const uint32 offset) const {
        return (_buf[offset] | (_buf[offset + 1] << 8));
    }
    inline uint32 access4(const uint32 offset) const {
        return _buf[offset] | (_buf[offset + 1] << 8) |
               (_buf[offset + 2] << 16) | (_buf[offset + 3] << 24);
    }
    inline uint8 *access(const uint32 offset) {
        return _buf + offset;
    }
    inline uint8 *access() {
        return _bufPtr;
    }

    //
    // Assign a value to a location in the stack
    //

    inline void assign1(const uint32 offset, const uint8 val) {
        const_cast<uint8 *>(_buf)[offset]   = static_cast<uint8>(val     & 0xFF);
    }
    inline void assign2(const uint32 offset, const uint16 val) {
        const_cast<uint8 *>(_buf)[offset]   = static_cast<uint8>(val     & 0xFF);
        const_cast<uint8 *>(_buf)[offset + 1] = static_cast<uint8>((val >> 8) & 0xFF);
    }
    inline void assign4(const uint32 offset, const uint32 val) {
        const_cast<uint8 *>(_buf)[offset]   = static_cast<uint8>(val      & 0xFF);
        const_cast<uint8 *>(_buf)[offset + 1] = static_cast<uint8>((val >> 8)  & 0xFF);
        const_cast<uint8 *>(_buf)[offset + 2] = static_cast<uint8>((val >> 16) & 0xFF);
        const_cast<uint8 *>(_buf)[offset + 3] = static_cast<uint8>((val >> 24) & 0xFF);
    }
    inline void assign(const uint32 offset, const uint8 *in, const uint32 len) {
        memcpy(const_cast<uint8 *>(_buf) + offset, in, len);
    }
};

class DynamicUCStack : public BaseUCStack {
public:
    DynamicUCStack(uint32 len = 0x1000) : BaseUCStack(len, new uint8[len]) { }
    ~DynamicUCStack() override {
        delete [] _buf;
    }

#ifdef USE_DYNAMIC_UCSTACK
#define UCStack DynamicUCStack
    void save(Common::WriteStream *ws);
    bool load(Common::ReadStream *rs, uint32 version);
#endif
};

#ifndef USE_DYNAMIC_UCSTACK
class UCStack : public BaseUCStack {
    uint8   _bufArray[0x1000];
public:
    UCStack() : BaseUCStack(0x1000, _bufArray) { }
    ~UCStack() override { }

    void save(Common::WriteStream *ws);
    bool load(Common::ReadStream *rs, uint32 version);
};
#endif

} // End of namespace Ultima8
} // End of namespace Ultima

#endif