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debug.c

/****************************************************************************
*
*                                   Realmode X86 Emulator Library
*
*                 Copyright (C) 1996-1999 SciTech Software, Inc.
*                            Copyright (C) David Mosberger-Tang
*                                Copyright (C) 1999 Egbert Eich
*
*  ========================================================================
*
*  Permission to use, copy, modify, distribute, and sell this software and
*  its documentation for any purpose is hereby granted without fee,
*  provided that the above copyright notice appear in all copies and that
*  both that copyright notice and this permission notice appear in
*  supporting documentation, and that the name of the authors not be used
*  in advertising or publicity pertaining to distribution of the software
*  without specific, written prior permission.  The authors makes no
*  representations about the suitability of this software for any purpose.
*  It is provided "as is" without express or implied warranty.
*
*  THE AUTHORS DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
*  INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
*  EVENT SHALL THE AUTHORS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
*  CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF
*  USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
*  OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
*  PERFORMANCE OF THIS SOFTWARE.
*
*  ========================================================================
*
* Language:       ANSI C
* Environment:    Any
* Developer:    Kendall Bennett
*
* Description:  This file contains the code to handle debugging of the
*                       emulator.
*
****************************************************************************/

#include "x86emu/x86emui.h"
#ifndef NO_SYS_HEADERS
#include <stdarg.h>
#include <stdlib.h>
#endif

/*----------------------------- Implementation ----------------------------*/

#ifdef DEBUG

static void     print_encoded_bytes (u16 s, u16 o);
static void     print_decoded_instruction (void);
static int      parse_line (char *s, int *ps, int *n);
  
/* should look something like debug's output. */
void X86EMU_trace_regs (void)
{
      if (DEBUG_TRACE()) {
            x86emu_dump_regs();
    }
      if (DEBUG_DECODE() && ! DEBUG_DECODE_NOPRINT()) {
            printk("%04x:%04x ",M.x86.saved_cs, M.x86.saved_ip);
            print_encoded_bytes( M.x86.saved_cs, M.x86.saved_ip);
            print_decoded_instruction();
    }
}

void X86EMU_trace_xregs (void)
{
      if (DEBUG_TRACE()) {
            x86emu_dump_xregs();
    }
}

void x86emu_just_disassemble (void)
{
    /*
     * This routine called if the flag DEBUG_DISASSEMBLE is set kind
     * of a hack!
     */
      printk("%04x:%04x ",M.x86.saved_cs, M.x86.saved_ip);
      print_encoded_bytes( M.x86.saved_cs, M.x86.saved_ip);
      print_decoded_instruction();
}

static void disassemble_forward (u16 seg, u16 off, int n)
{
      X86EMU_sysEnv tregs;
      int i;
      u8 op1;
    /*
     * hack, hack, hack.  What we do is use the exact machinery set up
     * for execution, except that now there is an additional state
     * flag associated with the "execution", and we are using a copy
     * of the register struct.  All the major opcodes, once fully
     * decoded, have the following two steps: TRACE_REGS(r,m);
     * SINGLE_STEP(r,m); which disappear if DEBUG is not defined to
     * the preprocessor.  The TRACE_REGS macro expands to:
     *
     * if (debug&DEBUG_DISASSEMBLE) 
     *     {just_disassemble(); goto EndOfInstruction;}
     *     if (debug&DEBUG_TRACE) trace_regs(r,m);
     *
     * ......  and at the last line of the routine. 
     *
     * EndOfInstruction: end_instr();
     *
     * Up to the point where TRACE_REG is expanded, NO modifications
     * are done to any register EXCEPT the IP register, for fetch and
     * decoding purposes.
     *
     * This was done for an entirely different reason, but makes a
     * nice way to get the system to help debug codes.
     */
      tregs = M;
    tregs.x86.R_IP = off;
    tregs.x86.R_CS = seg;
    
    /* reset the decoding buffers */
    tregs.x86.enc_str_pos = 0;
    tregs.x86.enc_pos = 0;
    
    /* turn on the "disassemble only, no execute" flag */
    tregs.x86.debug |= DEBUG_DISASSEMBLE_F;
 
    /* DUMP NEXT n instructions to screen in straight_line fashion */
    /*
     * This looks like the regular instruction fetch stream, except
     * that when this occurs, each fetched opcode, upon seeing the
     * DEBUG_DISASSEMBLE flag set, exits immediately after decoding
     * the instruction.  XXX --- CHECK THAT MEM IS NOT AFFECTED!!!
     * Note the use of a copy of the register structure...
     */
    for (i=0; i<n; i++) {
            op1 = (*sys_rdb)(((u32)M.x86.R_CS<<4) + (M.x86.R_IP++));
            (x86emu_optab[op1])(op1);
    }
    /* end major hack mode. */
}

void x86emu_check_ip_access (void)
{
    /* NULL as of now */
}

void x86emu_check_sp_access (void)
{
}

void x86emu_check_mem_access (u32 dummy)
{
      /*  check bounds, etc */
}

void x86emu_check_data_access (uint dummy1, uint dummy2)
{
      /*  check bounds, etc */
}

void x86emu_inc_decoded_inst_len (int x)
{
      M.x86.enc_pos += x;
}

void x86emu_decode_printf (char *x)
{
      sprintf(M.x86.decoded_buf+M.x86.enc_str_pos,"%s",x);
      M.x86.enc_str_pos += strlen(x);
}

void x86emu_decode_printf2 (char *x, int y)
{
      char temp[100];
      sprintf(temp,x,y);
      sprintf(M.x86.decoded_buf+M.x86.enc_str_pos,"%s",temp);
      M.x86.enc_str_pos += strlen(temp);
}

void x86emu_end_instr (void)
{
      M.x86.enc_str_pos = 0;
      M.x86.enc_pos = 0;
}

static void print_encoded_bytes (u16 s, u16 o)
{
    int i;
    char buf1[64];
      for (i=0; i< M.x86.enc_pos; i++) {
            sprintf(buf1+2*i,"%02x", fetch_data_byte_abs(s,o+i));
    }
      printk("%-20s",buf1);
}

static void print_decoded_instruction (void)
{
      printk("%s", M.x86.decoded_buf);
}

void x86emu_print_int_vect (u16 iv)
{
      u16 seg,off;

      if (iv > 256) return;
      seg   = fetch_data_word_abs(0,iv*4);
      off   = fetch_data_word_abs(0,iv*4+2);
      printk("%04x:%04x ", seg, off);
}

void X86EMU_dump_memory (u16 seg, u16 off, u32 amt)
{
      u32 start = off & 0xfffffff0;
      u32 end  = (off+16) & 0xfffffff0;
      u32 i;
      u32 current;

      current = start;
      while (end <= off + amt) {
            printk("%04x:%04x ", seg, start);
            for (i=start; i< off; i++)
              printk("   ");
            for (       ; i< end; i++)
              printk("%02x ", fetch_data_byte_abs(seg,i));
            printk("\n");
            start = end;
            end = start + 16;
      }
}

void x86emu_single_step (void)
{
    char s[1024];
    int ps[10];
    int ntok;
    int cmd;
    int done;
            int segment;
    int offset;
    static int breakpoint;
    static int noDecode = 1;
    
    char *p;

            if (DEBUG_BREAK()) {
                        if (M.x86.saved_ip != breakpoint) {
                                    return;
                        } else {
                M.x86.debug &= ~DEBUG_DECODE_NOPRINT_F;
                                    M.x86.debug |= DEBUG_TRACE_F;
                                    M.x86.debug &= ~DEBUG_BREAK_F;
                                    print_decoded_instruction ();
                                    X86EMU_trace_regs();
                        }
            }
    done=0;
      offset = M.x86.saved_ip;
    while (!done) {
        printk("-");
        p = fgets(s, 1023, stdin);
        cmd = parse_line(s, ps, &ntok);
        switch(cmd) {
          case 'u':
                  disassemble_forward(M.x86.saved_cs,(u16)offset,10);
            break;
          case 'd':  
                                          if (ntok == 2) {
                                                      segment = M.x86.saved_cs;
                                                      offset = ps[1];
                                                      X86EMU_dump_memory(segment,(u16)offset,16);
                                                      offset += 16;
                                          } else if (ntok == 3) {
                                                      segment = ps[1];
                                                      offset = ps[2];
                                                      X86EMU_dump_memory(segment,(u16)offset,16);
                                                      offset += 16;
                                          } else {
                                                      segment = M.x86.saved_cs;
                                                      X86EMU_dump_memory(segment,(u16)offset,16);
                                                      offset += 16;
                                          }
            break;
          case 'c':
                  M.x86.debug ^= DEBUG_TRACECALL_F;
            break;
          case 's':
                  M.x86.debug ^= DEBUG_SVC_F | DEBUG_SYS_F | DEBUG_SYSINT_F;
            break;
          case 'r':
                  X86EMU_trace_regs();
            break;
          case 'x':
                  X86EMU_trace_xregs();
            break;
          case 'g':
            if (ntok == 2) {
                breakpoint = ps[1];
            if (noDecode) {
                            M.x86.debug |= DEBUG_DECODE_NOPRINT_F;
            } else {
                            M.x86.debug &= ~DEBUG_DECODE_NOPRINT_F;
            }
            M.x86.debug &= ~DEBUG_TRACE_F;
            M.x86.debug |= DEBUG_BREAK_F;
            done = 1;
            }
            break;
          case 'q':
          M.x86.debug |= DEBUG_EXIT;
          return;
        case 'P':
            noDecode = (noDecode)?0:1;
            printk("Toggled decoding to %s\n",(noDecode)?"FALSE":"TRUE");
            break;
          case 't':
        case 0:
            done = 1;
            break;
        }   
    }
}

int X86EMU_trace_on(void)
{
      return M.x86.debug |= DEBUG_STEP_F | DEBUG_DECODE_F | DEBUG_TRACE_F;
}

int X86EMU_trace_off(void)
{
      return M.x86.debug &= ~(DEBUG_STEP_F | DEBUG_DECODE_F | DEBUG_TRACE_F);
}

static int parse_line (char *s, int *ps, int *n)
{
    int cmd;

    *n = 0;
    while(*s == ' ' || *s == '\t') s++;
    ps[*n] = *s;
    switch (*s) {
      case '\n':
        *n += 1;
        return 0;
      default:
        cmd = *s;
        *n += 1;
    }

      while (1) {
            while (*s != ' ' && *s != '\t' && *s != '\n')  s++;
            
            if (*s == '\n')
                  return cmd;
            
            while(*s == ' ' || *s == '\t') s++;
            
            sscanf(s,"%x",&ps[*n]);
            *n += 1;
      }
}

#endif /* DEBUG */

void x86emu_dump_regs (void)
{
      printk("\tAX=%04x  ", M.x86.R_AX );
      printk("BX=%04x  ", M.x86.R_BX );
      printk("CX=%04x  ", M.x86.R_CX );
      printk("DX=%04x  ", M.x86.R_DX );
      printk("SP=%04x  ", M.x86.R_SP );
      printk("BP=%04x  ", M.x86.R_BP );
      printk("SI=%04x  ", M.x86.R_SI );
      printk("DI=%04x\n", M.x86.R_DI );
      printk("\tDS=%04x  ", M.x86.R_DS );
      printk("ES=%04x  ", M.x86.R_ES );
      printk("SS=%04x  ", M.x86.R_SS );
      printk("CS=%04x  ", M.x86.R_CS );
      printk("IP=%04x   ", M.x86.R_IP );
      if (ACCESS_FLAG(F_OF))    printk("OV ");     /* CHECKED... */
      else                        printk("NV ");
      if (ACCESS_FLAG(F_DF))    printk("DN ");
      else                        printk("UP ");
      if (ACCESS_FLAG(F_IF))    printk("EI ");
      else                        printk("DI ");
      if (ACCESS_FLAG(F_SF))    printk("NG ");
      else                        printk("PL ");
      if (ACCESS_FLAG(F_ZF))    printk("ZR ");
      else                        printk("NZ ");
      if (ACCESS_FLAG(F_AF))    printk("AC ");
      else                        printk("NA ");
      if (ACCESS_FLAG(F_PF))    printk("PE ");
      else                        printk("PO ");
      if (ACCESS_FLAG(F_CF))    printk("CY ");
      else                        printk("NC ");
      printk("\n");
}

void x86emu_dump_xregs (void)
{
      printk("\tEAX=%08x  ", M.x86.R_EAX );
      printk("EBX=%08x  ", M.x86.R_EBX );
      printk("ECX=%08x  ", M.x86.R_ECX );
      printk("EDX=%08x  \n", M.x86.R_EDX );
      printk("\tESP=%08x  ", M.x86.R_ESP );
      printk("EBP=%08x  ", M.x86.R_EBP );
      printk("ESI=%08x  ", M.x86.R_ESI );
      printk("EDI=%08x\n", M.x86.R_EDI );
      printk("\tDS=%04x  ", M.x86.R_DS );
      printk("ES=%04x  ", M.x86.R_ES );
      printk("SS=%04x  ", M.x86.R_SS );
      printk("CS=%04x  ", M.x86.R_CS );
      printk("EIP=%08x\n\t", M.x86.R_EIP );
      if (ACCESS_FLAG(F_OF))    printk("OV ");     /* CHECKED... */
      else                        printk("NV ");
      if (ACCESS_FLAG(F_DF))    printk("DN ");
      else                        printk("UP ");
      if (ACCESS_FLAG(F_IF))    printk("EI ");
      else                        printk("DI ");
      if (ACCESS_FLAG(F_SF))    printk("NG ");
      else                        printk("PL ");
      if (ACCESS_FLAG(F_ZF))    printk("ZR ");
      else                        printk("NZ ");
      if (ACCESS_FLAG(F_AF))    printk("AC ");
      else                        printk("NA ");
      if (ACCESS_FLAG(F_PF))    printk("PE ");
      else                        printk("PO ");
      if (ACCESS_FLAG(F_CF))    printk("CY ");
      else                        printk("NC ");
      printk("\n");
}

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