/*
 * DOS Virtual Machine
 *
 * Copyright 1998 Ove Kåven
 *
 * This code hasn't been completely cleaned up yet.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <unistd.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/stat.h>
#include "windows.h"
#include "winbase.h"
#include "winnt.h"
#include "sig_context.h"
#include "msdos.h"
#include "miscemu.h"
#include "debugger.h"
#include "debug.h"
#include "module.h"
#include "task.h"
#include "ldt.h"
#include "dosexe.h"
#include "dosmod.h"

void (*ctx_debug_call)(int sig,CONTEXT*ctx)=NULL;
BOOL32 (*instr_emu_call)(SIGCONTEXT*ctx)=NULL;

#ifdef MZ_SUPPORTED

#include <sys/mman.h>
#include <sys/vm86.h>

static void DOSVM_Dump( LPDOSTASK lpDosTask, int fn, int sig,
                        struct vm86plus_struct*VM86 )
{
 unsigned iofs;
 BYTE*inst;
 int x;

 switch (VM86_TYPE(fn)) {
  case VM86_SIGNAL:
   printf("Trapped signal %d\n",sig); break;
  case VM86_UNKNOWN:
   printf("Trapped unhandled GPF\n"); break;
  case VM86_INTx:
   printf("Trapped INT %02x\n",VM86_ARG(fn)); break;
  case VM86_STI:
   printf("Trapped STI\n"); break;
  case VM86_PICRETURN:
   printf("Trapped due to pending PIC request\n"); break;
  case VM86_TRAP:
   printf("Trapped debug request\n"); break;
  default:
   printf("Trapped unknown VM86 type %d arg %d\n",VM86_TYPE(fn),VM86_ARG(fn)); break;
 }
#define REGS VM86->regs
 fprintf(stderr,"AX=%04lX CX=%04lX DX=%04lX BX=%04lX\n",REGS.eax,REGS.ecx,REGS.edx,REGS.ebx);
 fprintf(stderr,"SI=%04lX DI=%04lX SP=%04lX BP=%04lX\n",REGS.esi,REGS.edi,REGS.esp,REGS.ebp);
 fprintf(stderr,"CS=%04X DS=%04X ES=%04X SS=%04X\n",REGS.cs,REGS.ds,REGS.es,REGS.ss);
 fprintf(stderr,"IP=%04lX EFLAGS=%08lX\n",REGS.eip,REGS.eflags);

 iofs=((DWORD)REGS.cs<<4)+REGS.eip;
#undef REGS
 inst=(BYTE*)lpDosTask->img+iofs;
 printf("Opcodes:");
 for (x=0; x<8; x++) printf(" %02x",inst[x]);
 printf("\n");
}

static int DOSVM_Int( int vect, PCONTEXT context, LPDOSTASK lpDosTask )
{
 extern UINT16 DPMI_wrap_seg;

 if (vect==0x31) {
  if (CS_reg(context)==DPMI_wrap_seg) {
   /* exit from real-mode wrapper */
   return -1;
  }
  /* we could probably move some other dodgy stuff here too from dpmi.c */
 }
 INT_RealModeInterrupt(vect,context);
 return 0;
}

static void DOSVM_SimulateInt( int vect, PCONTEXT context, LPDOSTASK lpDosTask )
{
 FARPROC16 handler=INT_GetRMHandler(vect);
 WORD*stack=(WORD*)(V86BASE(context)+(((DWORD)SS_reg(context))<<4)+SP_reg(context));

 *(--stack)=FL_reg(context);
 *(--stack)=CS_reg(context);
 *(--stack)=IP_reg(context);
 SP_reg(context)-=6;
 CS_reg(context)=SELECTOROF(handler);
 IP_reg(context)=OFFSETOF(handler);
}

#define CV CP(eax,EAX); CP(ecx,ECX); CP(edx,EDX); CP(ebx,EBX); \
           CP(esi,ESI); CP(edi,EDI); CP(esp,ESP); CP(ebp,EBP); \
           CP(cs,CS); CP(ds,DS); CP(es,ES); \
           CP(ss,SS); CP(fs,FS); CP(gs,GS); \
           CP(eip,EIP); CP(eflags,EFL)

static int DOSVM_Process( LPDOSTASK lpDosTask, int fn, int sig,
                          struct vm86plus_struct*VM86 )
{
 SIGCONTEXT sigcontext;
 CONTEXT context;
 int ret=0;

 if (VM86_TYPE(fn)==VM86_UNKNOWN) {
  /* INSTR_EmulateInstruction needs a SIGCONTEXT, not a CONTEXT... */
#define CP(x,y) y##_sig(&sigcontext) = VM86->regs.x
  CV;
#undef CP
  if (instr_emu_call) ret=instr_emu_call(&sigcontext);
#define CP(x,y) VM86->regs.x = y##_sig(&sigcontext)
  CV;
#undef CP
  if (ret) return 0;
  ret=0;
 }
#define CP(x,y) y##_reg(&context) = VM86->regs.x
 CV;
#undef CP
 (void*)V86BASE(&context)=lpDosTask->img;

 switch (VM86_TYPE(fn)) {
  case VM86_SIGNAL:
   TRACE(int,"DOS module caught signal %d\n",sig);
   if (sig==SIGALRM) {
    DOSVM_SimulateInt(8,&context,lpDosTask);
   } else
   if (sig==SIGHUP) {
    if (ctx_debug_call) ctx_debug_call(SIGTRAP,&context);
   } else
   if ((sig==SIGILL)||(sig==SIGSEGV)) {
    if (ctx_debug_call) ctx_debug_call(SIGILL,&context);
   } else {
    DOSVM_Dump(lpDosTask,fn,sig,VM86);
    ret=-1;
   }
   break;
  case VM86_UNKNOWN: /* unhandled GPF */
   DOSVM_Dump(lpDosTask,fn,sig,VM86);
   if (ctx_debug_call) ctx_debug_call(SIGSEGV,&context); else ret=-1;
   break;
  case VM86_INTx:
   if (TRACE_ON(relay))
    DPRINTF("Call DOS int 0x%02x (EAX=%08lx) ret=%04lx:%04lx\n",VM86_ARG(fn),context.Eax,context.SegCs,context.Eip);
   ret=DOSVM_Int(VM86_ARG(fn),&context,lpDosTask);
   if (TRACE_ON(relay))
    DPRINTF("Ret  DOS int 0x%02x (EAX=%08lx) ret=%04lx:%04lx\n",VM86_ARG(fn),context.Eax,context.SegCs,context.Eip);
   break;
  case VM86_STI:
   break;
  case VM86_PICRETURN:
   printf("Trapped due to pending PIC request\n"); break;
  case VM86_TRAP:
   if (ctx_debug_call) ctx_debug_call(SIGTRAP,&context);
   break;
  default:
   DOSVM_Dump(lpDosTask,fn,sig,VM86);
   ret=-1;
 }

#define CP(x,y) VM86->regs.x = y##_reg(&context)
 CV;
#undef CP
 return ret;
}

int DOSVM_Enter( PCONTEXT context )
{
 TDB *pTask = (TDB *)GlobalLock16( GetCurrentTask() );
 NE_MODULE *pModule = NE_GetPtr( pTask->hModule );
 LPDOSTASK lpDosTask;
 struct vm86plus_struct VM86;
 int stat,len,sig;
 fd_set readfds,exceptfds;

 GlobalUnlock16( GetCurrentTask() );
 if (!pModule) {
  ERR(module,"No task is currently active!\n");
  return -1;
 }
 if (!(lpDosTask=pModule->lpDosTask)) {
  /* MZ_CreateProcess or MZ_AllocDPMITask should have been called first */
  ERR(module,"dosmod has not been initialized!");
  return -1;
 }

 if (context) {
#define CP(x,y) VM86.regs.x = y##_reg(context)
  CV;
#undef CP
 } else {
/* initial setup */
  /* allocate standard DOS handles */
  FILE_InitProcessDosHandles(); 
  /* registers */
  memset(&VM86,0,sizeof(VM86));
  VM86.regs.cs=lpDosTask->init_cs;
  VM86.regs.eip=lpDosTask->init_ip;
  VM86.regs.ss=lpDosTask->init_ss;
  VM86.regs.esp=lpDosTask->init_sp;
  VM86.regs.ds=lpDosTask->psp_seg;
  VM86.regs.es=lpDosTask->psp_seg;
  /* hmm, what else do we need? */
 }

 /* main exchange loop */
 do {
  stat = VM86_ENTER;
  errno = 0;
  /* transmit VM86 structure to dosmod task */
  if (write(lpDosTask->write_pipe,&stat,sizeof(stat))!=sizeof(stat)) {
   ERR(module,"dosmod sync lost, errno=%d\n",errno);
   return -1;
  }
  if (write(lpDosTask->write_pipe,&VM86,sizeof(VM86))!=sizeof(VM86)) {
   ERR(module,"dosmod sync lost, errno=%d\n",errno);
   return -1;
  }
  /* wait for response, with async events enabled */
  FD_ZERO(&readfds);
  FD_ZERO(&exceptfds);
  SIGNAL_MaskAsyncEvents(FALSE);
  do {
   FD_SET(lpDosTask->read_pipe,&readfds);
   FD_SET(lpDosTask->read_pipe,&exceptfds);
   select(lpDosTask->read_pipe+1,&readfds,NULL,&exceptfds,NULL);
  } while (!(FD_ISSET(lpDosTask->read_pipe,&readfds)||
             FD_ISSET(lpDosTask->read_pipe,&exceptfds)));
  SIGNAL_MaskAsyncEvents(TRUE);
  /* read response (with async events disabled to avoid some strange problems) */
  do {
   if ((len=read(lpDosTask->read_pipe,&stat,sizeof(stat)))!=sizeof(stat)) {
    if (((errno==EINTR)||(errno==EAGAIN))&&(len<=0)) {
     WARN(module,"rereading dosmod return code due to errno=%d, result=%d\n",errno,len);
     continue;
    }
    ERR(module,"dosmod sync lost reading return code, errno=%d, result=%d\n",errno,len);
    return -1;
   }
  } while (0);
  TRACE(module,"dosmod return code=%d\n",stat);
  do {
   if ((len=read(lpDosTask->read_pipe,&VM86,sizeof(VM86)))!=sizeof(VM86)) {
    if (((errno==EINTR)||(errno==EAGAIN))&&(len<=0)) {
     WARN(module,"rereading dosmod VM86 structure due to errno=%d, result=%d\n",errno,len);
     continue;
    }
    ERR(module,"dosmod sync lost reading VM86 structure, errno=%d, result=%d\n",errno,len);
    return -1;
   }
  } while (0);
  if ((stat&0xff)==DOSMOD_SIGNAL) {
   do {
    if ((len=read(lpDosTask->read_pipe,&sig,sizeof(sig)))!=sizeof(sig)) {
     if (((errno==EINTR)||(errno==EAGAIN))&&(len<=0)) {
      WARN(module,"rereading dosmod signal due to errno=%d, result=%d\n",errno,len);
      continue;
     }
     ERR(module,"dosmod sync lost reading signal, errno=%d, result=%d\n",errno,len);
     return -1;
    }
   } while (0);
  } else sig=0;
  /* got response */
 } while (DOSVM_Process(lpDosTask,stat,sig,&VM86)>=0);

 if (context) {
#define CP(x,y) y##_reg(context) = VM86.regs.x
  CV;
#undef CP
 }
 return 0;
}

void DOSVM_SetTimer( unsigned ticks )
{
 TDB *pTask = (TDB *)GlobalLock16( GetCurrentTask() );
 NE_MODULE *pModule = NE_GetPtr( pTask->hModule );
 int stat=DOSMOD_SET_TIMER;
 struct timeval tim;

 GlobalUnlock16( GetCurrentTask() );
 if (pModule&&pModule->lpDosTask) {
  /* the PC clocks ticks at 1193180 Hz */
  tim.tv_sec=0;
  tim.tv_usec=((unsigned long long)ticks*1000000)/1193180;
  /* sanity check */
  if (!tim.tv_usec) tim.tv_usec=1;

  if (write(pModule->lpDosTask->write_pipe,&stat,sizeof(stat))!=sizeof(stat)) {
   ERR(module,"dosmod sync lost, errno=%d\n",errno);
   return;
  }
  if (write(pModule->lpDosTask->write_pipe,&tim,sizeof(tim))!=sizeof(tim)) {
   ERR(module,"dosmod sync lost, errno=%d\n",errno);
   return;
  }
  /* there's no return */
 }
}

unsigned DOSVM_GetTimer( void )
{
 TDB *pTask = (TDB *)GlobalLock16( GetCurrentTask() );
 NE_MODULE *pModule = NE_GetPtr( pTask->hModule );
 int stat=DOSMOD_GET_TIMER;
 struct timeval tim;

 GlobalUnlock16( GetCurrentTask() );
 if (pModule&&pModule->lpDosTask) {
  if (write(pModule->lpDosTask->write_pipe,&stat,sizeof(stat))!=sizeof(stat)) {
   ERR(module,"dosmod sync lost, errno=%d\n",errno);
   return 0;
  }
  /* read response */
  if (read(pModule->lpDosTask->read_pipe,&tim,sizeof(tim))!=sizeof(tim)) {
   ERR(module,"dosmod sync lost, errno=%d\n",errno);
   return 0;
  }
  return ((unsigned long long)tim.tv_usec*1193180)/1000000;
 }
 return 0;
}

void MZ_Tick( WORD handle )
{
 /* find the DOS task that has the right system_timer handle... */
 /* should usually be the current, so let's just be lazy... */
 TDB *pTask = (TDB*)GlobalLock16( GetCurrentTask() );
 NE_MODULE *pModule = pTask ? NE_GetPtr( pTask->hModule ) : NULL;
 LPDOSTASK lpDosTask = pModule ? pModule->lpDosTask : NULL;

 GlobalUnlock16( GetCurrentTask() );
 if (lpDosTask&&(lpDosTask->system_timer==handle)) {
  /* BIOS timer tick */
  (*((DWORD*)(((BYTE*)(lpDosTask->img))+0x46c)))++;
 }
}

#else /* !MZ_SUPPORTED */

int DOSVM_Enter( PCONTEXT context )
{
 ERR(module,"DOS realmode not supported on this architecture!\n");
 return -1;
}

void MZ_Tick( WORD handle ) {}
void DOSVM_SetTimer( unsigned ticks ) {}
unsigned DOSVM_GetTimer( void ) { return 0; }

#endif