muddle/src/variable.c
2024-01-30 17:44:08 -06:00

87 lines
2.6 KiB
C

/*
* Copyright (c) 2024 Scott Duensing, scott@kangaroopunch.com
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#include "variable.h"
#include "state.h"
#include "portme.h"
#include "messages.h"
#include "story.h"
#include "memory.h"
uint32_t variableAddressGlobal(uint16_t var) {
return storyGlobalVariableTableAddress() + ((var - 0x10) * 2);
}
uint16_t variableLoad(uint16_t var) {
// Is it on the stack?
if (var < 16) return __state.stack[variableAddress(var, 0)];
// Nope, global.
return ZPEEKW(variableAddressGlobal(var));
}
void variableStore(uint16_t var, uint16_t value) {
uint32_t addr;
if (var < 16) {
// On stack.
addr = variableAddress(var, 1);
__state.stack[addr] = value;
} else {
// Global.
addr = variableAddressGlobal(var);
ZPOKEW(addr, value);
}
}
uint8_t variableAddress(uint8_t var, bool writing) {
uint16_t numLocals;
if (var == 0) { // top of stack
if (writing) {
if (__state.sp >= sizeof(__state.stack)) portDie(MSG_INT_STACK_OVERFLOW);
#ifdef DEBUGGING
printf("Push stack\n");
#endif
return __state.sp++;
} else {
if (__state.sp == 0) portDie(MSG_INT_STACK_UNDERFLOW);
numLocals = __state.bp ? __state.stack[__state.bp - 1] : 0;
if ((__state.bp + numLocals) >= sizeof(__state.stack)) portDie(MSG_INT_STACK_UNDERFLOW);
#ifdef DEBUGGING
printf("Pop stack\n");
#endif
return --__state.sp;
} // writing
} // var
if ((var >= 0x1) && (var <= 0xf)) { // Local var.
if (__state.stack[__state.bp - 1] <= (var - 1)) portDie(MSG_INT_REF_UNALLOCATED_LOCAL);
return __state.bp + (var - 1);
}
return storyGlobalVariableTableAddress() + ((var - 0x10) * 2);
}