Turned sim65 into a lightweight cc65 execution environment.
The sim65 source code has been a construction site for over a decade. I was looking for a simple cc65 program execution environment for regression tests. So I decided to re-purpose sim65 for that task by removing about everything but the 6502 emulation. There's no memory mapped i/o emulation whatsoever. Rather exit(), open(), close(), read() and write() calls are supported by mapping them through a thin paravirtualization layer to the corresponding host os functions. Note: The sim65 6502 emulation provides means to switch between 6502 and 65C02 emulation but currently there are no actual 65C02 opcodes implemented.
This commit is contained in:
Oliver Schmidt
255
src/sim65/paravirt.c
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255
src/sim65/paravirt.c
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/*****************************************************************************/
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/* */
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/* paravirt.c */
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/* */
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/* Paravirtualization for the sim65 6502 simulator */
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/* */
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/* */
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/* */
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/* (C) 2013-2013 Ullrich von Bassewitz */
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/* R<>merstrasse 52 */
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/* D-70794 Filderstadt */
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/* EMail: uz@cc65.org */
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/* */
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/* */
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/* This software is provided 'as-is', without any expressed or implied */
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/* warranty. In no event will the authors be held liable for any damages */
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/* arising from the use of this software. */
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/* */
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/* Permission is granted to anyone to use this software for any purpose, */
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/* including commercial applications, and to alter it and redistribute it */
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/* freely, subject to the following restrictions: */
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/* */
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/* 1. The origin of this software must not be misrepresented; you must not */
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/* claim that you wrote the original software. If you use this software */
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/* in a product, an acknowledgment in the product documentation would be */
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/* appreciated but is not required. */
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/* 2. Altered source versions must be plainly marked as such, and must not */
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/* be misrepresented as being the original software. */
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/* 3. This notice may not be removed or altered from any source */
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/* distribution. */
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/* */
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/*****************************************************************************/
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#include <stdlib.h>
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#include <fcntl.h>
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#if defined(_MSC_VER)
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/* Microsoft compiler */
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# include <io.h>
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# pragma warning(disable : 4996)
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# define O_INITIAL O_BINARY
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#else
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/* Anyone else */
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# include <unistd.h>
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# define O_INITIAL 0
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#endif
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/* common */
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#include "print.h"
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#include "xmalloc.h"
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/* sim65 */
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#include "6502.h"
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#include "memory.h"
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#include "paravirt.h"
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/*****************************************************************************/
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/* Data */
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/*****************************************************************************/
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typedef void (*PVFunc) (CPURegs* Regs);
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/*****************************************************************************/
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/* Code */
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/*****************************************************************************/
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static unsigned char Pop (CPURegs* Regs)
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{
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return MemReadByte (0x0100 + ++Regs->SP);
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}
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static unsigned PopParam (unsigned char Incr)
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{
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unsigned SP = MemReadZPWord (0x00);
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unsigned Val = MemReadWord (SP);
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SP += Incr;
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MemWriteByte (0x00, SP);
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SP >>= 8;
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MemWriteByte (0x01, SP);
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return Val;
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}
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static void PVExit (CPURegs* Regs)
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{
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Print (stdout, 1, "PVExit ($%02X)\n", Regs->AC);
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exit (Regs->AC);
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}
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static void PVOpen (CPURegs* Regs)
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{
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char Path[1024];
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int OFlag = O_INITIAL;
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unsigned RetVal, I = 0;
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unsigned Mode = PopParam (Regs->YR - 4);
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unsigned Flags = PopParam (2);
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unsigned Name = PopParam (2);
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do {
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Path[I] = MemReadByte (Name++);
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}
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while (Path[I++]);
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Print (stdout, 2, "PVOpen (\"%s\", $%04X)\n", Path, Flags);
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switch (Flags & 0x03) {
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case 0x01:
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OFlag |= O_RDONLY;
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break;
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case 0x02:
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OFlag |= O_WRONLY;
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break;
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case 0x03:
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OFlag |= O_RDWR;
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break;
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}
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if (Flags & 0x10) {
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OFlag |= O_CREAT;
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}
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if (Flags & 0x20) {
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OFlag |= O_TRUNC;
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}
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if (Flags & 0x40) {
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OFlag |= O_APPEND;
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}
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if (Flags & 0x80) {
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OFlag |= O_EXCL;
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}
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/* Avoid gcc warning */
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(void) Mode;
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RetVal = open (Path, OFlag);
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Regs->AC = RetVal & 0xFF;
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RetVal >>= 8;
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Regs->XR = RetVal & 0xFF;
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}
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static void PVClose (CPURegs* Regs)
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{
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unsigned RetVal;
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unsigned FD = Regs->AC + (Regs->XR << 8);
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Print (stdout, 2, "PVClose ($%04X)\n", FD);
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RetVal = close (FD);
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Regs->AC = RetVal & 0xFF;
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RetVal >>= 8;
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Regs->XR = RetVal & 0xFF;
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}
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static void PVRead (CPURegs* Regs)
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{
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unsigned char* Data;
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unsigned RetVal, I = 0;
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unsigned Count = Regs->AC + (Regs->XR << 8);
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unsigned Buf = PopParam (2);
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unsigned FD = PopParam (2);
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Print (stdout, 2, "PVRead ($%04X, $%04X, $%04X)\n", FD, Buf, Count);
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Data = xmalloc (Count);
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RetVal = read (FD, Data, Count);
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if (RetVal != (unsigned) -1) {
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while (I < RetVal) {
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MemWriteByte (Buf++, Data[I++]);
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}
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}
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xfree (Data);
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Regs->AC = RetVal & 0xFF;
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RetVal >>= 8;
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Regs->XR = RetVal & 0xFF;
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}
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static void PVWrite (CPURegs* Regs)
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{
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unsigned char* Data;
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unsigned RetVal, I = 0;
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unsigned Count = Regs->AC + (Regs->XR << 8);
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unsigned Buf = PopParam (2);
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unsigned FD = PopParam (2);
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Print (stdout, 2, "PVWrite ($%04X, $%04X, $%04X)\n", FD, Buf, Count);
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Data = xmalloc (Count);
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while (I < Count) {
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Data[I++] = MemReadByte (Buf++);
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}
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RetVal = write (FD, Data, Count);
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xfree (Data);
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Regs->AC = RetVal & 0xFF;
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RetVal >>= 8;
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Regs->XR = RetVal & 0xFF;
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}
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static const PVFunc Hooks[] = {
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PVExit,
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PVOpen,
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PVClose,
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PVRead,
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PVWrite,
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};
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void ParaVirtualization (CPURegs* Regs)
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/* Potentially execute paravirtualization hook */
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{
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/* Check for paravirtualization address range */
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if (Regs->PC < 0xFFF0 ||
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Regs->PC >= 0xFFF0 + sizeof (Hooks) / sizeof (Hooks[0])) {
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return;
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}
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/* Call paravirtualization hook */
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Hooks[Regs->PC - 0xFFF0] (Regs);
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/* Simulate RTS */
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Regs->PC = Pop(Regs) + (Pop(Regs) << 8) + 1;
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}
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