//This step is only used by the Word/Byte versions
void BuildLoadStore_WordAndByte(LoadStoreBuilder b)
{
//Phase 0 - Choose memory size (word/byte)
string originalName = b.name;
b.opcode &= ~loadstore_byte_bit;
//Case 1: Word
b.memorySize = ARMPluginInterfaces.MemorySize.Word;
BuildLoadStore_Offset(b);
//Case 2: Byte
b.name += "B";
b.opcode |= loadstore_byte_bit;
b.memorySize = ARMPluginInterfaces.MemorySize.Byte;
BuildLoadStore_Offset(b);
b.name = originalName;
b.opcode &= ~loadstore_byte_bit;
}
//This version applies to Word or Byte versions
void BuildLoadStore_Offset(LoadStoreBuilder b)
{
//Phase 1 - Set operand type (register/immediate)
//Clear register flag
b.opcode &= ~loadstore_register_bit;
//Immediate Offset (register flag 0)
b.ComputeOffset = ComputeOffsetImmediate;
BuildLoadStore_OffsetAddress(b);
//Register Offset (register flag 1)
b.opcode |= loadstore_register_bit;
b.ComputeOffset = ComputeOffsetRegister;
BuildLoadStore_OffsetAddress(b);
//Clear register flag
b.opcode &= ~loadstore_register_bit;
}
void BuildLoadStore_OffsetAddress(LoadStoreBuilder b)
{
//Phase 2 - Set add/subtract behavior (i.e. is offset_address = "address + offset" or "address - offset"
//Clear add/subtract flag (U bit)
b.opcode &= ~offset_add_bit;
//Subtract (U bit = 0)
b.ComputeOffsetAddress = ComputeOffsetAddressSubtract;
BuildLoadStore_IndexWriteBack(b);
//Add (U bit = 1)
b.opcode |= offset_add_bit;
b.ComputeOffsetAddress = ComputeOffsetAddressAdd;
BuildLoadStore_IndexWriteBack(b);
//Clear add/subtract flag
b.opcode &= ~offset_add_bit;
}
//This version applies to Halfword/Signed Halfword/Signed Byte versions
void BuildLoadStore_Offset_SignedByte_HalfWord(LoadStoreBuilder b)
{
//Phase 1 - Set operand type (register/immediate)
//Clear register flag
b.opcode &= ~loadstore_immediate_bit_hw;
//Register Offset (immediate flag 0)
b.ComputeOffset = ComputeOffsetRegisterHW;
BuildLoadStore_OffsetAddress(b);
//Immediate Offset (immediate flag 1)
b.opcode |= loadstore_immediate_bit_hw;
b.ComputeOffset = ComputeOffsetImmediateHW;
BuildLoadStore_OffsetAddress(b);
//Clear register flag
b.opcode &= ~loadstore_immediate_bit_hw;
}
void BuildLoadStore_IndexWriteBack(LoadStoreBuilder b)
{
//Phase 3 - Set indexing (pre or post) and writeback behavior
//Even though these are theoretically independent options, there is a special case
//So we handle them all here.
//Clear relevant flags:
b.opcode &= ~(loadstore_preindex_bit | writeback_bit);
//Case 1: Post-indexing (index_bit = 0) with writeback (by default) and writeback_bit = 0
//Note that post-indexing is supposed to always have writeback, so the correct
//protocol is for W = 0 when index_bit = 0.
b.ComputeFinalAddress = ComputeAddressPostIndex;
b.WritebackAddress = WritebackAddressEnabled;
FinishBuildingLoadStoreOp(b);
b.opcode &= ~(loadstore_preindex_bit | writeback_bit);
//Case 2: Post-indexing (index_bit = 0) with writeback (by default) and writeback_bit = 1
//This actually corresponds to a special type of instruction with a T suffix (e.g. STRT)
//cf. ARMv7 A8.8.92
//For now, we ignore it.
//TODO stop ignoring it.
//Case 3: Pre-indexing (index_bit = 1) with no writeback (writeback_bit = 0)
b.opcode |= loadstore_preindex_bit;
b.ComputeFinalAddress = ComputeAddressPreIndex;
b.WritebackAddress = WritebackAddressDisabled;
FinishBuildingLoadStoreOp(b);
b.opcode &= ~(loadstore_preindex_bit | writeback_bit);
//Case 3: Pre-indexing (index_bit = 1) with writeback (writeback_bit = 1)
b.opcode |= loadstore_preindex_bit | writeback_bit;
b.ComputeFinalAddress = ComputeAddressPreIndex;
b.WritebackAddress = WritebackAddressEnabled;
FinishBuildingLoadStoreOp(b);
//Clear relevant flags:
b.opcode &= ~(loadstore_preindex_bit | writeback_bit);
}
internal void RegisterARMLoadStoreOps()
{
uint base_opcode;
uint wildcard_mask; //The values of bits 20-27 vary between branches. The bit B (bit 4) in the specification is irrelevant here.
LoadStoreBuilder b = new LoadStoreBuilder();
//Create variants of STR and STRB
base_opcode = 0x04000000;
wildcard_mask = 0xf00fffff; //The values of bits 20-27 vary between branches. The bit B (bit 4) in the specification is irrelevant here.
b.name = "STR";
b.opcode = base_opcode;
b.wildcard_mask = wildcard_mask;
b.LoadStoreMemory = StoreMemory;
BuildLoadStore_WordAndByte(b);
//Create variants of LDR and LDRB
base_opcode = 0x04100000;
wildcard_mask = 0xf00fffff;
b.name = "LDR";
b.opcode = base_opcode;
b.wildcard_mask = wildcard_mask;
b.LoadStoreMemory = LoadMemory;
BuildLoadStore_WordAndByte(b);
//Create variants of STRH
base_opcode = 0x000000b0;
wildcard_mask = 0xf00fff0f;
b.name = "STRH";
b.opcode = base_opcode;
b.wildcard_mask = wildcard_mask;
b.LoadStoreMemory = StoreMemory;
b.memorySize = ARMPluginInterfaces.MemorySize.HalfWord;
BuildLoadStore_Offset_SignedByte_HalfWord(b);
//Create variants of LDRH
base_opcode = 0x001000b0;
wildcard_mask = 0xf00fff0f;
b.name = "LDRH";
b.opcode = base_opcode;
b.wildcard_mask = wildcard_mask;
b.LoadStoreMemory = LoadMemory;
b.memorySize = ARMPluginInterfaces.MemorySize.HalfWord;
BuildLoadStore_Offset_SignedByte_HalfWord(b);
//Create variants of LDRSB (signed byte)
base_opcode = 0x001000d0;
wildcard_mask = 0xf00fff0f;
b.name = "LDRSB";
b.opcode = base_opcode;
b.wildcard_mask = wildcard_mask;
b.LoadStoreMemory = LoadMemorySignedByte;
b.memorySize = ARMPluginInterfaces.MemorySize.Byte;
BuildLoadStore_Offset_SignedByte_HalfWord(b);
//Create variants of LDRSH (signed halfword)
base_opcode = 0x001000f0;
wildcard_mask = 0xf00fff0f;
b.name = "LDRSB";
b.opcode = base_opcode;
b.wildcard_mask = wildcard_mask;
b.LoadStoreMemory = LoadMemorySignedHalfword;
b.memorySize = ARMPluginInterfaces.MemorySize.HalfWord;
BuildLoadStore_Offset_SignedByte_HalfWord(b);
//LDRD and STRD are load/store "dual" instructions which load or store two
//adjacent words to two registers.
//LDRD is v5TE only
//RegisterOpcode(0x000000d0, 0xf1afff0f, null, "LDRD"); //LDRD (Register)
//RegisterOpcode(0x004000d0, 0xf1afff0f, null, "LDRD"); //LDRD (immediate)
//STRD is v5 and up only
//RegisterOpcode(0x000000f0, 0xf1afff0f, null, "STRD"); //STRD (Register)
//RegisterOpcode(0x004000f0, 0xf1afff0f, null, "STRD"); //STRD (immediate)
}
internal void FinishBuildingLoadStoreOp(LoadStoreBuilder b)
{
InstructionFunc handler = GenerateLoadStoreInstruction(b.ComputeOffset, b.ComputeOffsetAddress, b.ComputeFinalAddress, b.WritebackAddress, b.memorySize, b.LoadStoreMemory);
RegisterOpcode(b.opcode, b.wildcard_mask, handler, b.name);
}
