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/* 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/>.
*
*/
/*
* Based on ScottFree interpreter version 1.14 developed by Swansea
* University Computer Society without disassembly of any other game
* drivers, only of game databases as permitted by EEC law (for purposes
* of compatibility).
*
* Licensed under GPLv2
*
* https://github.com/angstsmurf/spatterlight/tree/master/terps/scott
*/
#include "glk/scott/ring_buffer.h"
namespace Glk {
namespace Scott {
// The hidden definition of our circular buffer structure
struct CircularBuf {
uint8_t *_buffer;
size_t _head;
size_t _tail;
size_t _max; // of the buffer
bool _full;
};
// Return a pointer to a struct instance
cbuf_handle_t circularBufInit(uint8_t *buffer, size_t size) {
cbuf_handle_t cbuf = new CircularBuf;
cbuf->_buffer = buffer;
cbuf->_max = size;
circularBufReset(cbuf);
return cbuf;
}
void circularBufReset(cbuf_handle_t me) {
me->_head = 0;
me->_tail = 0;
me->_full = false;
}
void circularBufFree(cbuf_handle_t me) {
delete me;
}
bool circularBufFull(cbuf_handle_t me) {
return me->_full;
}
bool circularBufEmpty(cbuf_handle_t me) {
return (!me->_full && (me->_head == me->_tail));
}
size_t circularBufCapacity(cbuf_handle_t me) {
return me->_max;
}
size_t circularBufSize(cbuf_handle_t me) {
size_t size = me->_max;
if (!me->_full) {
if (me->_head >= me->_tail) {
size = (me->_head - me->_tail);
} else {
size = (me->_max + me->_head - me->_tail);
}
}
return size;
}
static void advancePointer(cbuf_handle_t me) {
if (me->_full) {
if (++(me->_tail) == me->_max) {
me->_tail = 0;
}
}
if (++(me->_head) == me->_max) {
me->_head = 0;
}
me->_full = (me->_head == me->_tail);
}
static void retreatPointer(cbuf_handle_t me) {
me->_full = false;
if (++(me->_tail) == me->_max) {
me->_tail = 0;
}
}
int circularBufPut(cbuf_handle_t me, uint8_t x, uint8_t y) {
int r = -1;
if (!circularBufFull(me)) {
me->_buffer[me->_head] = x;
advancePointer(me);
if (!circularBufFull(me)) {
me->_buffer[me->_head] = y;
advancePointer(me);
r = 0;
}
}
return r;
}
int circularBufGet(cbuf_handle_t me, int *x, int *y) {
int r = -1;
if (!circularBufEmpty(me)) {
*x = me->_buffer[me->_tail];
retreatPointer(me);
if (!circularBufEmpty(me)) {
*y = me->_buffer[me->_tail];
retreatPointer(me);
r = 0;
}
}
return r;
}
} // End of namespace Scott
} // End of namespace Glk
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