fc

fc.py

@@ -0,0 +1,42 @@
+#!/usr/bin/env python3
+import sys
+import ast
+
+def compare_files(file1, file2, offset1=0, offset2=0):
+    with open(file1, "rb") as f1, open(file2, "rb") as f2:
+        # Seek to the specified offsets
+        offset1 = ast.literal_eval(offset1)
+        offset2 = ast.literal_eval(offset2)
+        f1.seek(offset1)
+        f2.seek(offset2)
+
+        index = 0
+        while True:
+            byte1 = f1.read(1)
+            byte2 = f2.read(1)
+
+            # Stop if we reach the end of either file
+            if byte1 == b"" or byte2 == b"":
+                break
+
+            if byte1 != byte2:
+                # Print differences in the desired format
+                addr1 = f'{index + offset1:08X} {index + offset2:08X}'  # 32-bit hex address for file1
+                byte1_hex = f'{ord(byte1):02X}'
+                byte2_hex = f'{ord(byte2):02X}'
+                print(f"{addr1}: {byte1_hex} {byte2_hex}")
+
+            index += 1
+
+if __name__ == "__main__":
+    if len(sys.argv) != 5:
+        print("Usage: python compare_files.py <file1> <file2> <offset1> <offset2>")
+        sys.exit(1)
+
+    file1 = sys.argv[1]
+    file2 = sys.argv[2]
+    offset1 = sys.argv[3]
+    offset2 = sys.argv[4]
+
+    compare_files(file1, file2, offset1, offset2)
+

include/custom.h

@@ -10,6 +10,7 @@ typedef Bit32u dd;
 
 extern bool collect_rt_info;
 extern bool collect_rt_info_vars;
+extern bool compare_instructions;
 extern Bit32u last_ip;
 
 #include <unordered_set>
@@ -62,7 +63,7 @@ struct _STATE;
 
         void push(_STATE *_state, dd value);
 
-        void pop(_STATE *_state);
+        void pop(_STATE *_state, size_t word_size);
 
         void print(_STATE *_state);
         void print_frame(const Frame& f);

meson.build

@@ -41,7 +41,7 @@ prefers_static_libs = (get_option('default_library') == 'static')
 summary('Build type',     get_option('buildtype'), section : 'Build Summary')
 summary('Install prefix', get_option('prefix'),    section : 'Build Summary')
 
-extra_flags = ['-ggdb3','-gdwarf-4','-rdynamic','-I/usr/include/SDL2','-Wmaybe-uninitialized', '-Wno-unused-variable','-Wno-unused-function','-mno-ms-bitfields', '-Wno-multichar', '-Wno-address-of-packed-member','-DDOSBOX_CUSTOM', '-DM2CDEBUG=1']
+extra_flags = ['-ggdb3','-gdwarf-4','-rdynamic','-I/usr/include/SDL2','-Wmaybe-uninitialized', '-Wno-unused-variable','-Wno-unused-function','-mno-ms-bitfields', '-Wno-multichar', '-Wno-address-of-packed-member','-DDOSBOX_CUSTOM', '-DM2CDEBUG=1', '-D_SHADOW_STACK']
 if host_machine.system() == 'windows'
   extra_flags += '-Wno-pedantic-ms-format'
 endif

src/cpu/core_normal.cpp

@@ -168,9 +168,9 @@ void print_instruction_direct(Bit16u newcs, Bit32u newip)
 extern int custom_runs;
 
 Bits CPU_Core_Normal_Run(void) {
-	if (last_ip != 0xffff and last_ip != cpu_regs.ip.dword[0] and custom_runs) {
+	if (compare_instructions && last_ip != 0xffff and last_ip != cpu_regs.ip.dword[0] and custom_runs) {
 		m2c::log_debug("IP changed dbx: %x now: %x\n", last_ip, cpu_regs.ip.dword[0]);
-//		exit(1);
+		exit(1);
 	}
 
 	while (CPU_Cycles-->0) {

src/cpu/cpu.cpp

@@ -154,7 +154,7 @@ void CPU_Push32(Bitu value) {
 
 Bitu CPU_Pop16(void) {
 #ifdef SHADOW_STACK
-        m2c::shadow_stack.pop(0);
+        m2c::shadow_stack.pop(0, 2);
 #endif
 	Bitu val=mem_readw(SegPhys(ss) + (reg_esp & cpu.stack.mask));
 	reg_esp=(reg_esp&cpu.stack.notmask)|((reg_esp+2)&cpu.stack.mask);
@@ -163,7 +163,7 @@ Bitu CPU_Pop16(void) {
 
 Bitu CPU_Pop32(void) {
 #ifdef SHADOW_STACK
-        m2c::shadow_stack.pop(0);
+        m2c::shadow_stack.pop(0, 4);
 #endif
 	Bitu val=mem_readd(SegPhys(ss) + (reg_esp & cpu.stack.mask));
 	reg_esp=(reg_esp&cpu.stack.notmask)|((reg_esp+4)&cpu.stack.mask);

src/custom/asm.h

@@ -120,6 +120,13 @@ typedef int Bits;
 #ifndef NOSDL
 extern struct SDL_Renderer *renderer;
 #endif
+
+namespace m2c{
+typedef dd _offsets;
+    struct _STATE;
+}
+extern  bool __dispatch_call(m2c::_offsets __i, struct m2c::_STATE* _state);
+
 namespace m2c {
 extern db vgaPalette[256*3];
 
@@ -496,7 +503,7 @@ inline long getdata(const long& s)
 #endif
 
 #ifdef DOSBOX_CUSTOM
-#define PUSH(a) {m2c::PUSH_((dw)a);}  // WARNING !!! Hacking to word
+#define PUSH(a) {m2c::PUSH_(a);}  // WARNING !!! Hacking to word
 #define POP(a) {m2c::POP_(a);}
 
 
@@ -545,7 +552,7 @@ inline long getdata(const long& s)
 {
   X86_REGREF
  #ifdef SHADOW_STACK
-  m2c::shadow_stack.pop(_state);
+  m2c::shadow_stack.pop(_state, sizeof(a));
  #endif
 
  #if M2CDEBUG > 0
@@ -1064,7 +1071,7 @@ AFFECT_CF(((Destination<<m2c::bitsizeof(Destination)+Source) >> (32 - Count)) &
         AFFECT_CF(false);                                \
         AFFECT_OF(false);                                \
         AFFECT_AF(false);                                \
-    } \
+    } else CPU_Exception(0); \
 }
 
 #define AAM AAM1(10)
@@ -1204,19 +1211,28 @@ AFFECT_CF(((Destination<<m2c::bitsizeof(Destination)+Source) >> (32 - Count)) &
 }
 
 
-#define IDIV2(op1)                                \
-{                                                            \
-    Bits val=(int16_t)(op1);                            \
-    if (val==0) CPU_Exception(0);                                    \
-    Bits num=(int32_t)((dx<<16)|ax);                    \
-    Bits quo=num/val;                                        \
-    int16_t rem=(int16_t)(num % val);                            \
-    int16_t quo16s=(int16_t)quo;                                \
-    if (quo!=(int32_t)quo16s) CPU_Exception(0);                    \
-    dx=rem;                                                \
-    ax=quo16s;                                            \
-    AFFECT_OF(false);                                    \
+#define IDIV2(op1) m2c::IDIV2_(op1, _state)
+
+
+static   /* MYINLINE*/ void IDIV2_(dw op1, _STATE* _state) {
+        X86_REGREF
+		const auto val = static_cast<int16_t>(op1);
+    if (val==0) {
+log_debug("~~fail1\n");CPU_Exception(0);__dispatch_call((cs<<16)+ip, _state);
+}
+		const auto num = (dx << 16) | ax; 
+		const auto quo = num / val; 
+		const auto rem = num % val; 
+		const auto quo16s = static_cast<int16_t>(quo); 
+		if (quo != quo16s) 
+			{
+log_debug("~~fail2\n");CPU_Exception(0);__dispatch_call((cs<<16)+ip, _state);
 }
+		ax = quo16s; 
+		dx = static_cast<int16_t>(rem); 
+    AFFECT_OF(false);                                    
+	}
+
 
 #define IDIV4(op1)                                \
 {                                                            \

src/custom/custom.cpp

@@ -27,7 +27,7 @@ bool trace_instructions = true;            // m2c::debug >= 1;
 bool trace_instructions_to_stdout = false; // m2c::debug >= 1;
 bool compare_instructions = true; // m2c::debug >= 1;// 1 || m2c::debug == 2 ||
                                   // m2c::debug == 3;
-bool complex_self_modifications = true;
+bool complex_self_modifications = false;
 bool collect_rt_info = false;
 bool collect_rt_info_vars = false;
 

src/custom/shadowstack.cpp

@@ -37,7 +37,7 @@ namespace m2c{
    return m_ss[esp].itwascall;
   }
 
-  void ShadowStack::pop(_STATE * _state)
+  void ShadowStack::pop(_STATE * _state, size_t word_size)
   {
      if (!m_active && !m_forceactive) 
        {
@@ -82,15 +82,15 @@ namespace m2c{
                 }
 //		else log_debug ("m_current %x not initialized\n", m_current);
 
-                m_current += 2; 
+                m_current += word_size; 
 //                  log_debug ("m_current %x\n", m_current);
               }
 
             while (m_current <= esp);
 //log_debug("m_itisret %d m_current %x m_ss.at(m_current-2).itwascall %d\n",m_itisret, m_current, m_ss.at(m_current-2).itwascall);
-           if (m_itisret && m_ss.at(m_current-2).itwascall) {--m_needtoskipcall;log_debug("decreased m_needtoskipcall=%d\n",m_needtoskipcall);}
+           if (m_itisret && m_ss.at(m_current-word_size).itwascall) {--m_needtoskipcall;log_debug("decreased m_needtoskipcall=%d\n",m_needtoskipcall);}
 
-      m_currentdeep = m_ss.at(m_current-2).call_deep;
+      m_currentdeep = m_ss.at(m_current-word_size).call_deep;
                   log_debug ("m2c::counter %x m_deep %d collected m_currentdeep %d m_needtoskipcall %d m_itisret %d\n", counter, m_deep, m_currentdeep,m_needtoskipcall,m_itisret);
           }
 
@@ -108,13 +108,6 @@ log_debug("decreasedeep m_deep=%d ",m_deep);
         bool ShadowStack::needtoskipcalls(){
 /*
 log_debug("ret m_currentdeep=%d ",m_currentdeep);
-m_needtoskipcall=m_currentdeep?m_deep-m_currentdeep:0; 
-if (m_needtoskipcall<0) {m_needtoskipcall=0;}
-//m_deep=m_currentdeep?m_currentdeep-1:m_deep; 
---m_deep;
-log_debug("m_deep=%d ",m_deep);
-m_currentdeep=0;
-log_debug("m_currentdeep=%d\n",m_currentdeep);
 */
 log_debug("m_needtoskipcall=%d\n",m_needtoskipcall);
 return m_needtoskipcall;}

src/custom/src/f.exe_seg35ab.cpp

@@ -133,7 +133,7 @@ cs=0x274d;eip=0x00009a; 	T(MOV(dx, *(dw*)(raddr(ds,bx+0x1A0D))));	// 117114
 cs=0x274d;eip=0x00009e; 	T(MOV(al, *(raddr(ds,bx+0x1A0F))));	// 117115                  mov     al, [bx+1A0Fh] ;~ 274D:009E
 cs=0x274d;eip=0x0000a2; 	T(CBW);	// 117116                  cbw ;~ 274D:00A2
 cs=0x274d;eip=0x0000a3; 	T(XCHG(ax, dx));	// 117117                  xchg    ax, dx ;~ 274D:00A3
-cs=0x274d;eip=0x0000a4; 	R(IDIV2(cx));	// 117118                  idiv    cx ;~ 274D:00A4
+cs=0x274d;eip=0x0000a4; 	T(IDIV2(cx));	// 117118                  idiv    cx ;~ 274D:00A4
 cs=0x274d;eip=0x0000a6; 	T(CWD);	// 117119                  cwd ;~ 274D:00A6
 cs=0x274d;eip=0x0000a7; 	T(OR(ax, ax));	// 117120                  or      ax, ax ;~ 274D:00A7
 cs=0x274d;eip=0x0000a9; 	T(ADD(ax, word_48bbc));	// 117121                  add     ax, word_48BBC ;~ 274D:00A9