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/****************************************************************************
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* Realmode X86 Emulator Library
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* Copyright (C) 1996-1999 SciTech Software, Inc.
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* Copyright (C) David Mosberger-Tang
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* Copyright (C) 1999 Egbert Eich
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* ========================================================================
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* Permission to use, copy, modify, distribute, and sell this software and
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* its documentation for any purpose is hereby granted without fee,
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* provided that the above copyright notice appear in all copies and that
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* both that copyright notice and this permission notice appear in
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* supporting documentation, and that the name of the authors not be used
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* in advertising or publicity pertaining to distribution of the software
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* without specific, written prior permission. The authors makes no
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* representations about the suitability of this software for any purpose.
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* It is provided "as is" without express or implied warranty.
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* THE AUTHORS DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
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* INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
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* EVENT SHALL THE AUTHORS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
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* CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF
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* USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
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* OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
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* PERFORMANCE OF THIS SOFTWARE.
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* ========================================================================
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* Developer: Kendall Bennett
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* Description: This file contains the code to handle debugging of the
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****************************************************************************/
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#include "x86emu/x86emui.h"
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#ifndef NO_SYS_HEADERS
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/*----------------------------- Implementation ----------------------------*/
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static void print_encoded_bytes (u16 s, u16 o);
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static void print_decoded_instruction (void);
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static int parse_line (char *s, int *ps, int *n);
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/* should look something like debug's output. */
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void X86EMU_trace_regs (void)
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if (DEBUG_DECODE() && ! DEBUG_DECODE_NOPRINT()) {
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printk("%04x:%04x ",M.x86.saved_cs, M.x86.saved_ip);
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print_encoded_bytes( M.x86.saved_cs, M.x86.saved_ip);
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print_decoded_instruction();
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void X86EMU_trace_xregs (void)
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void x86emu_just_disassemble (void)
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* This routine called if the flag DEBUG_DISASSEMBLE is set kind
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printk("%04x:%04x ",M.x86.saved_cs, M.x86.saved_ip);
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print_encoded_bytes( M.x86.saved_cs, M.x86.saved_ip);
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print_decoded_instruction();
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static void disassemble_forward (u16 seg, u16 off, int n)
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* hack, hack, hack. What we do is use the exact machinery set up
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* for execution, except that now there is an additional state
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* flag associated with the "execution", and we are using a copy
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* of the register struct. All the major opcodes, once fully
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* decoded, have the following two steps: TRACE_REGS(r,m);
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* SINGLE_STEP(r,m); which disappear if DEBUG is not defined to
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* the preprocessor. The TRACE_REGS macro expands to:
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* if (debug&DEBUG_DISASSEMBLE)
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* {just_disassemble(); goto EndOfInstruction;}
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* if (debug&DEBUG_TRACE) trace_regs(r,m);
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* ...... and at the last line of the routine.
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* EndOfInstruction: end_instr();
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* Up to the point where TRACE_REG is expanded, NO modifications
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* are done to any register EXCEPT the IP register, for fetch and
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* This was done for an entirely different reason, but makes a
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* nice way to get the system to help debug codes.
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tregs.x86.R_IP = off;
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tregs.x86.R_CS = seg;
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/* reset the decoding buffers */
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tregs.x86.enc_str_pos = 0;
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tregs.x86.enc_pos = 0;
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/* turn on the "disassemble only, no execute" flag */
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tregs.x86.debug |= DEBUG_DISASSEMBLE_F;
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/* DUMP NEXT n instructions to screen in straight_line fashion */
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* This looks like the regular instruction fetch stream, except
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* that when this occurs, each fetched opcode, upon seeing the
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* DEBUG_DISASSEMBLE flag set, exits immediately after decoding
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* the instruction. XXX --- CHECK THAT MEM IS NOT AFFECTED!!!
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* Note the use of a copy of the register structure...
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for (i=0; i<n; i++) {
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op1 = (*sys_rdb)(((u32)M.x86.R_CS<<4) + (M.x86.R_IP++));
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(x86emu_optab[op1])(op1);
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/* end major hack mode. */
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void x86emu_check_ip_access (void)
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void x86emu_check_sp_access (void)
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void x86emu_check_mem_access (u32 dummy)
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/* check bounds, etc */
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void x86emu_check_data_access (uint dummy1, uint dummy2)
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/* check bounds, etc */
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void x86emu_inc_decoded_inst_len (int x)
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void x86emu_decode_printf (char *x)
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sprintf(M.x86.decoded_buf+M.x86.enc_str_pos,"%s",x);
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M.x86.enc_str_pos += strlen(x);
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void x86emu_decode_printf2 (char *x, int y)
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sprintf(M.x86.decoded_buf+M.x86.enc_str_pos,"%s",temp);
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M.x86.enc_str_pos += strlen(temp);
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void x86emu_end_instr (void)
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M.x86.enc_str_pos = 0;
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static void print_encoded_bytes (u16 s, u16 o)
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for (i=0; i< M.x86.enc_pos; i++) {
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sprintf(buf1+2*i,"%02x", fetch_data_byte_abs(s,o+i));
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printk("%-20s",buf1);
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static void print_decoded_instruction (void)
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printk("%s", M.x86.decoded_buf);
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void x86emu_print_int_vect (u16 iv)
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if (iv > 256) return;
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seg = fetch_data_word_abs(0,iv*4);
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off = fetch_data_word_abs(0,iv*4+2);
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printk("%04x:%04x ", seg, off);
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void X86EMU_dump_memory (u16 seg, u16 off, u32 amt)
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u32 start = off & 0xfffffff0;
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u32 end = (off+16) & 0xfffffff0;
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while (end <= off + amt) {
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printk("%04x:%04x ", seg, start);
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for (i=start; i< off; i++)
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printk("%02x ", fetch_data_byte_abs(seg,i));
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void x86emu_single_step (void)
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static int breakpoint;
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static int noDecode = 1;
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if (M.x86.saved_ip != breakpoint) {
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M.x86.debug &= ~DEBUG_DECODE_NOPRINT_F;
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M.x86.debug |= DEBUG_TRACE_F;
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M.x86.debug &= ~DEBUG_BREAK_F;
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print_decoded_instruction ();
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offset = M.x86.saved_ip;
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p = fgets(s, 1023, stdin);
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cmd = parse_line(s, ps, &ntok);
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disassemble_forward(M.x86.saved_cs,(u16)offset,10);
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segment = M.x86.saved_cs;
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X86EMU_dump_memory(segment,(u16)offset,16);
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} else if (ntok == 3) {
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X86EMU_dump_memory(segment,(u16)offset,16);
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segment = M.x86.saved_cs;
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X86EMU_dump_memory(segment,(u16)offset,16);
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M.x86.debug ^= DEBUG_TRACECALL_F;
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M.x86.debug ^= DEBUG_SVC_F | DEBUG_SYS_F | DEBUG_SYSINT_F;
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X86EMU_trace_xregs();
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M.x86.debug |= DEBUG_DECODE_NOPRINT_F;
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M.x86.debug &= ~DEBUG_DECODE_NOPRINT_F;
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M.x86.debug &= ~DEBUG_TRACE_F;
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M.x86.debug |= DEBUG_BREAK_F;
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M.x86.debug |= DEBUG_EXIT;
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noDecode = (noDecode)?0:1;
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printk("Toggled decoding to %s\n",(noDecode)?"FALSE":"TRUE");
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int X86EMU_trace_on(void)
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return M.x86.debug |= DEBUG_STEP_F | DEBUG_DECODE_F | DEBUG_TRACE_F;
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int X86EMU_trace_off(void)
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return M.x86.debug &= ~(DEBUG_STEP_F | DEBUG_DECODE_F | DEBUG_TRACE_F);
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static int parse_line (char *s, int *ps, int *n)
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while(*s == ' ' || *s == '\t') s++;
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while (*s != ' ' && *s != '\t' && *s != '\n') s++;
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while(*s == ' ' || *s == '\t') s++;
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sscanf(s,"%x",&ps[*n]);
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void x86emu_dump_regs (void)
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printk("\tAX=%04x ", M.x86.R_AX );
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printk("BX=%04x ", M.x86.R_BX );
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printk("CX=%04x ", M.x86.R_CX );
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printk("DX=%04x ", M.x86.R_DX );
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printk("SP=%04x ", M.x86.R_SP );
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printk("BP=%04x ", M.x86.R_BP );
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printk("SI=%04x ", M.x86.R_SI );
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printk("DI=%04x\n", M.x86.R_DI );
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printk("\tDS=%04x ", M.x86.R_DS );
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printk("ES=%04x ", M.x86.R_ES );
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printk("SS=%04x ", M.x86.R_SS );
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printk("CS=%04x ", M.x86.R_CS );
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printk("IP=%04x ", M.x86.R_IP );
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if (ACCESS_FLAG(F_OF)) printk("OV "); /* CHECKED... */
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if (ACCESS_FLAG(F_DF)) printk("DN ");
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if (ACCESS_FLAG(F_IF)) printk("EI ");
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if (ACCESS_FLAG(F_SF)) printk("NG ");
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if (ACCESS_FLAG(F_ZF)) printk("ZR ");
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if (ACCESS_FLAG(F_AF)) printk("AC ");
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if (ACCESS_FLAG(F_PF)) printk("PE ");
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if (ACCESS_FLAG(F_CF)) printk("CY ");
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void x86emu_dump_xregs (void)
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printk("\tEAX=%08x ", M.x86.R_EAX );
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printk("EBX=%08x ", M.x86.R_EBX );
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printk("ECX=%08x ", M.x86.R_ECX );
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printk("EDX=%08x \n", M.x86.R_EDX );
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printk("\tESP=%08x ", M.x86.R_ESP );
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printk("EBP=%08x ", M.x86.R_EBP );
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printk("ESI=%08x ", M.x86.R_ESI );
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printk("EDI=%08x\n", M.x86.R_EDI );
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printk("\tDS=%04x ", M.x86.R_DS );
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printk("ES=%04x ", M.x86.R_ES );
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printk("SS=%04x ", M.x86.R_SS );
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printk("CS=%04x ", M.x86.R_CS );
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printk("EIP=%08x\n\t", M.x86.R_EIP );
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if (ACCESS_FLAG(F_OF)) printk("OV "); /* CHECKED... */
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if (ACCESS_FLAG(F_DF)) printk("DN ");
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if (ACCESS_FLAG(F_IF)) printk("EI ");
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if (ACCESS_FLAG(F_SF)) printk("NG ");
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if (ACCESS_FLAG(F_ZF)) printk("ZR ");
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if (ACCESS_FLAG(F_AF)) printk("AC ");
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if (ACCESS_FLAG(F_PF)) printk("PE ");
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if (ACCESS_FLAG(F_CF)) printk("CY ");