summaryrefslogtreecommitdiff
path: root/src/code/sim86.cpp
diff options
context:
space:
mode:
Diffstat (limited to 'src/code/sim86.cpp')
-rw-r--r--src/code/sim86.cpp375
1 files changed, 0 insertions, 375 deletions
diff --git a/src/code/sim86.cpp b/src/code/sim86.cpp
deleted file mode 100644
index 1e4ddfa..0000000
--- a/src/code/sim86.cpp
+++ /dev/null
@@ -1,375 +0,0 @@
-#include <stdio.h>
-#include <string.h>
-
-#include "sim86.h"
-#include "sim86_shared.h"
-
-global_variable u8 FlagToCharMapping[] = "CPAZSOIDT";
-global_variable u8 GlobalMemory[1*1024*1024] = {};
-
-internal void
-SetOrUnsetFlag(u32 *FlagsRegister, b32 Condition, flags_8086 Flag)
-{
- if(Condition)
- {
- *FlagsRegister |= Flag;
- }
- else
- {
- *FlagsRegister &= (~Flag);
- }
-}
-
-internal u32
-FlagsToString(char *Buffer, u32 Flags)
-{
- u32 Length = 0;
-
- for(u32 MappingIndex = 0;
- MappingIndex < ArrayCount(FlagToCharMapping);
- MappingIndex++)
- {
- u8 Char = FlagToCharMapping[MappingIndex];
- b32 IsBitSet = (Flags & 1);
- Flags >>= 1;
- if(IsBitSet)
- {
- Buffer[Length++] = Char;
- }
- }
-
- return Length;
-}
-
-internal void
-FlagsFromValue(u32 *FlagsRegister, u32 InstructionFlags, s32 Value)
-{
- u32 OldFlagsRegister = *FlagsRegister;
-
- u32 SignMask = (1 << ((InstructionFlags & Inst_Wide) ? 15 : 7));
- SetOrUnsetFlag(FlagsRegister, (Value & SignMask), Flag_Sign);
- SetOrUnsetFlag(FlagsRegister, (Value == 0), Flag_Zero);
-
- // NOTE(luca): Parity flag is set when in lower 8 bits have an even number of set bits.
- u32 OneBitsCount = 0;
- for(u32 BitsIndex = 0;
- BitsIndex < 8;
- BitsIndex++)
- {
- OneBitsCount += (Value & 1);
- Value >>= 1;
- }
- SetOrUnsetFlag(FlagsRegister, (!(OneBitsCount & 1)), Flag_Parity);
-
- // TODO(luca): Overflow flag
- // Were we adding positive numbers but produced a negative number?
-
- // TODO(luca): Carry flag
- // When twot numbers are added and the 17th bit would be set?
-
- // TODO(luca): Auxiliary carry flag
- // Carry for bottom 8 bits
- if(*FlagsRegister != OldFlagsRegister)
- {
- char OldFlagsString[ArrayCount(FlagToCharMapping)] = {};
- char FlagsString[ArrayCount(FlagToCharMapping)] = {};
- FlagsToString(OldFlagsString, OldFlagsRegister);
- FlagsToString(FlagsString, *FlagsRegister);
-
- printf(" flags:%s->%s", OldFlagsString, FlagsString);
- }
-}
-
-internal s32 *
-OperandToValue(s32 *Registers, u8 *Memory, instruction_operand *Operand)
-{
- s32 *Result = 0;
-
- if(0) {}
- else if(Operand->Type == Operand_Register)
- {
- Result = Registers + Operand->Register.Index;
- }
- else if(Operand->Type == Operand_Memory)
- {
- s32 CompleteDisplacement = Operand->Address.Displacement;
- Assert(Operand->Address.Terms[0].Register.Count == Operand->Address.Terms[1].Register.Count);
-
- u32 Count = Operand->Address.Terms[0].Register.Count;
- u32 Mask = ((u32)((-1)) >> (16 + (16 - Count*8)));
-
- CompleteDisplacement +=
- (Registers[Operand->Address.Terms[0].Register.Index] & Mask) +
- (Registers[Operand->Address.Terms[1].Register.Index] & Mask);
-
- Result = (s32 *)((u8 *)Memory + CompleteDisplacement);
- }
- else if(Operand->Type == Operand_Immediate)
- {
- Result = &Operand->Immediate.Value;
- }
- else if(Operand->Type != Operand_None)
- {
- Assert(0);
- }
-
- return Result;
-}
-
-internal void
-Run8086(psize MemorySize, u8 *Memory)
-{
- s32 Registers[Register_count] = {};
- u32 FlagsRegister = 0;
- u32 IPRegister = 0;
-
- while(IPRegister < MemorySize)
- {
- instruction Decoded;
- Sim86_Decode8086Instruction(MemorySize - IPRegister, Memory + IPRegister, &Decoded);
- if(Decoded.Op)
- {
- u32 OldIPRegister = IPRegister;
- IPRegister += Decoded.Size;
-
-#if SIM86_INTERNAL
- printf("Size:%u Op:%s Flags:0x%x ;", Decoded.Size, Sim86_MnemonicFromOperationType(Decoded.Op), Decoded.Flags);
-#endif
-
- instruction_operand *DestinationOperand = Decoded.Operands + 0;
- instruction_operand *SourceOperand = Decoded.Operands + 1;
-
- s32 *Destination = OperandToValue(Registers, Memory, DestinationOperand);
- s32 *Source = OperandToValue(Registers, Memory, SourceOperand);
-
- if(0) {}
- else if(Decoded.Op == Op_int3)
- {
- Assert(0);
- }
- else if(Decoded.Op == Op_mov)
- {
- s32 Old = *Destination;
- if(Decoded.Flags & Inst_Wide)
- {
- *(u16 *)Destination = *(u16 *)Source;
- }
- else
- {
- Assert((SourceOperand->Type == Operand_Immediate ||
- SourceOperand->Type == Operand_Memory) &&
- (SourceOperand->Register.Offset == 0));
- Assert((DestinationOperand->Type == Operand_Immediate || DestinationOperand->Type == Operand_Memory) && (DestinationOperand->Register.Offset == 0));
-
- u8 *SourceByte = (u8 *)Source + SourceOperand->Register.Offset;
- u8 *DestByte = (u8 *)Destination + DestinationOperand->Register.Offset;
-
- *DestByte = *SourceByte;
- }
-
-#if SIM86_INTERNAL
- if(DestinationOperand->Type == Operand_Register)
- {
- printf(" %s:0x%x->0x%x", Sim86_RegisterNameFromOperand(&DestinationOperand->Register),
- Old, *Destination);
- }
-#endif
- }
- else if(Decoded.Op == Op_cmp)
- {
- Assert(DestinationOperand->Type == Operand_Register);
- Assert(SourceOperand->Type == Operand_Register || SourceOperand->Type == Operand_Immediate);
-
- s32 Value = ((Decoded.Flags & Inst_Wide) ?
- (u16)((u16)*Destination - ((u16)*Source)) :
- (u8)((u8)*Destination - ((u8)*Source)));
-
- FlagsFromValue(&FlagsRegister, Decoded.Flags, Value);
- }
- else if(Decoded.Op == Op_sub)
- {
- Assert(DestinationOperand->Type == Operand_Register);
- Assert(SourceOperand->Type == Operand_Register || SourceOperand->Type == Operand_Immediate);
-
- s32 Old = *Destination;
- *Destination = ((Decoded.Flags & Inst_Wide) ?
- (u16)((u16)*Destination - ((u16)*Source)) :
- (u8)((u8)*Destination - ((u8)*Source)));
-
- printf(" %s:0x%x->0x%x",
- Sim86_RegisterNameFromOperand(&DestinationOperand->Register),
- Old, *Destination);
-
- FlagsFromValue(&FlagsRegister, Decoded.Flags, *Destination);
-
- }
- else if(Decoded.Op == Op_add)
- {
- Assert(DestinationOperand->Type == Operand_Register);
-
- s32 Old = *Destination;
-
- *Destination = ((Decoded.Flags & Inst_Wide) ?
- (u16)((u16)*Destination + ((u16)*Source)) :
- (u8)((u8)*Destination + ((u8)*Source)));
-
- printf(" %s:0x%x->0x%x",
- Sim86_RegisterNameFromOperand(&DestinationOperand->Register),
- Old, *Destination);
-
- FlagsFromValue(&FlagsRegister, Decoded.Flags, *Destination);
- }
- else if(Decoded.Op == Op_jne)
- {
- if(!(FlagsRegister & Flag_Zero))
- {
- IPRegister += *Destination;
- }
- }
- else if(Decoded.Op == Op_je)
- {
- if((FlagsRegister & Flag_Zero))
- {
- IPRegister += *Destination;
- }
- }
- else
- {
- Assert(0 && "Op not implemented yet.");
- }
-
-#if SIM86_INTERNAL
- printf(" ip:0x%x->0x%x", OldIPRegister, IPRegister);
-#endif
-
- }
- else
- {
- printf("Unrecognized instruction\n");
- break;
- }
-
-#if SIM86_INTERNAL
- printf("\n");
-#endif
-
- }
-
- printf("Final registers:\n");
- for(u32 RegisterIndex = Register_a;
- RegisterIndex < Register_ds + 1;
- RegisterIndex++)
- {
- register_access Register = {};
- Register.Index = RegisterIndex;
- Register.Offset = 0;
- Register.Count = 2;
-
- u32 Value = Registers[RegisterIndex];
- if(Value > 0)
- {
- printf(" %s: 0x%0x (%d)\n",
- Sim86_RegisterNameFromOperand(&Register),
- Value, Value);
- }
- }
- printf(" ip: 0x%04x (%d)\n", IPRegister, IPRegister);
-
- if(FlagsRegister)
- {
- char FlagsString[ArrayCount(FlagToCharMapping)] = {};
- FlagsToString(FlagsString, FlagsRegister);
- printf(" flags: %s\n", FlagsString);
- }
-}
-
-void PrintUsage(char *ExePath)
-{
- printf("usage: %s [-exec] <assembly>\n", ExePath);
-}
-
-int main(int ArgsCount, char *Args[])
-{
- u32 Version = Sim86_GetVersion();
-
-#if SIM86_INTERNAL
- printf("Sim86 Version: %u (expected %u)\n", Version, SIM86_VERSION);
-#endif
-
- if(Version != SIM86_VERSION)
- {
- printf("ERROR: Header file version doesn't match DLL.\n");
- return -1;
- }
-
- instruction_table Table;
- Sim86_Get8086InstructionTable(&Table);
-
-#if SIM86_INTERNAL
- printf("8086 Instruction Instruction Encoding Count: %u\n", Table.EncodingCount);
-#endif
-
- // print (default)
- // -exec (also execute the disassembled instructinos)
-
- b32 Execute = false;
- b32 Dump = false;
- char *FileName = 0;
- for(s32 ArgsIndex = 1;
- ArgsIndex < ArgsCount;
- ArgsIndex++)
- {
- char *Command = Args[ArgsIndex];
- if(0) {}
- else if(!strcmp(Command, "-exec"))
- {
- Execute = true;
- }
- else if(!strcmp(Command, "-dump"))
- {
- Dump = true;
- }
- else
- {
- FileName = Command;
- }
- }
-
- if(FileName)
- {
- FILE *File = fopen(FileName, "rb");
- if(File)
- {
- psize BytesWritten = fread(GlobalMemory, 1, sizeof(GlobalMemory), File);
- fclose(File);
-
- if(Execute)
- {
- printf("--- %s execution ---\n", FileName);
-
- Run8086(BytesWritten, GlobalMemory);
-
- if(Dump)
- {
- // NOTE(luca): We have to add ".data" or Gimp will throw an error.
- FILE *DumpFile = fopen("sim86_memory_0.data", "wb");
- fwrite(GlobalMemory, 1, sizeof(GlobalMemory), DumpFile);
- fclose(DumpFile);
- }
-
- }
- else
- {
- printf("ERROR: Disassembling not implemented yet.\n");
- }
-
- }
- else
- {
- printf("ERROR: Unable to open %s.\n", FileName);
- PrintUsage(Args[0]);
- }
- }
-
- return 0;
-}
generated by cgit v1.2.3-70-g09d2 (git 2.46.0) at 2025-11-25 22:52:51 +0000