From d195a11e3a7c1ec16644264097bb1af29631878b Mon Sep 17 00:00:00 2001 From: iximeow Date: Sat, 23 Dec 2023 15:41:29 -0800 Subject: more adjustments, backed by test discoveries * displacements in deref are now stored as their real value, not the scaled-down value parsed from instructions * byte and word relative branches have a distinct operand, not `ImmB`/`ImmW` * properly interpret 3-bit branch displacement of `bra.s` * show negative branch offsets as negatives * displacements shown as hex * memory access size suffixes actually displayed on instruction --- src/lib.rs | 165 ++++++++++++++++++++++++++++++++++++++++++++++++++++--------- 1 file changed, 142 insertions(+), 23 deletions(-) (limited to 'src') diff --git a/src/lib.rs b/src/lib.rs index 68f0819..0973a70 100644 --- a/src/lib.rs +++ b/src/lib.rs @@ -79,8 +79,69 @@ impl Default for Instruction { impl fmt::Display for Instruction { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { - write!(f, "{}", self.opcode())?; let ops = self.operands(); + let mut size = None; + for op in ops { + match op { + Operand::Nothing => {}, + /// one of the 16 32-bit general purpose registers: `R0 (sp)` through `R15`. + Operand::Register { num: _ } => {}, + /// a range of registers, from `start_gpr` to `end_gpr` + Operand::RegisterRange { start_gpr: _, end_gpr: _ } => {}, + /// one of the 16 32-bit general purpose registers, but a smaller part of it. typically + /// sign-extended to 32b for processing. + Operand::Subreg { num: _, width } => { + size = Some(*width); + break; + }, + Operand::Accumulator { num: _ } => {}, + /// `bfmov` and `bfmovz`, textually, describe the bitfield to be moved with three parameters. + /// those three parameters are expressed as this one operand. + Operand::BitfieldSpec { bf_spec: _ } => {}, + /// one of the 16 64-bit double-precision floating point registers: `DR0` through `DR15`. + Operand::DoubleReg { num: _ } => {}, + Operand::DoubleRegLow { num: _ } => {}, + Operand::DoubleRegHigh { num: _ } => {}, + Operand::ControlReg { reg: _ } => {}, + Operand::PSWBit { bit: _ } => {}, + Operand::Deref { gpr: _, disp: _, width } => { + size = Some(*width); + break; + }, + Operand::DerefIndexed { base: _, index: _, width } => { + size = Some(*width); + break; + }, + Operand::DoubleRegisterRange { start_reg: _, end_reg: _ } => {}, + Operand::DoubleControlRegisterRange { start_reg: _, end_reg: _ } => {}, + Operand::ImmB { imm: _ } => {}, + Operand::ImmW { imm: _ } => {}, + Operand::ImmL { imm: _ } => {}, + Operand::BrS { offset: _ } => { + size = Some(SizeCode::S); + break; + }, + Operand::BrB { offset: _ } => { + size = Some(SizeCode::B); + break; + }, + Operand::BrW { offset: _ } => { + size = Some(SizeCode::W); + break; + }, + /// a 24-bit immediate. this is used as a branch offset, and is treated as a sign-extended + /// 24-bit value, so it is represented as that extended form here. + Operand::BrA { offset: _ } => { + size = Some(SizeCode::A); + break; + }, + } + } + write!(f, "{}", self.opcode())?; + + if let Some(size) = size { + write!(f, ".{}", size)?; + } if let Some(op) = ops.get(0) { write!(f, " {}", op)?; } @@ -223,13 +284,19 @@ pub enum Operand { DoubleRegHigh { num: u8 }, ControlReg { reg: ControlReg }, PSWBit { bit: PSWBit }, + /// access to memory at the address produced by adding `gpr + disp`. in this operand, `disp` is + /// the exact number of bytes used for the offset access - this is in contrast to hardware, + /// where displacements are scaled down by the size of the scaled item. Deref { gpr: u8, disp: u32, width: SizeCode }, + /// access to memory at the address produced by adding `gpr(base) + gpr(index) * size(width)`. DerefIndexed { base: u8, index: u8, width: SizeCode }, DoubleRegisterRange { start_reg: u8, end_reg: u8 }, DoubleControlRegisterRange { start_reg: u8, end_reg: u8 }, - BrS(u8), ImmB { imm: u8 }, ImmW { imm: u16 }, + BrS { offset: u8 }, + BrB { offset: i8 }, + BrW { offset: i16 }, /// a 24-bit immediate. this is used as a branch offset, and is treated as a sign-extended /// 24-bit value, so it is represented as that extended form here. BrA { offset: i32 }, @@ -238,19 +305,39 @@ pub enum Operand { #[derive(Debug, Copy, Clone, PartialEq, Eq)] pub enum SizeCode { + S, B, W, + A, L, D, UW, } +impl fmt::Display for SizeCode { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + let text = match self { + SizeCode::S => "s", + SizeCode::B => "b", + SizeCode::W => "w", + SizeCode::A => "a", + SizeCode::L => "l", + SizeCode::D => "d", + SizeCode::UW => "uw", + }; + + f.write_str(text) + } +} + impl SizeCode { fn bytes(&self) -> u8 { match self { + SizeCode::S => 1, SizeCode::B => 1, SizeCode::W => 2, SizeCode::UW => 2, + SizeCode::A => 3, SizeCode::L => 4, SizeCode::D => 8, } @@ -299,7 +386,7 @@ impl fmt::Display for Operand { if *disp == 0 { write!(f, "[r{}]", gpr) } else { - write!(f, "{}[r{}]", disp, gpr) + write!(f, "{:x}h[r{}]", disp, gpr) } }, Operand::DerefIndexed { base, index, .. } => { @@ -314,22 +401,42 @@ impl fmt::Display for Operand { // TODO: give the control registers names... write!(f, "dcr{}-dcr{}", start_reg, end_reg) } - Operand::BrS(disp) => { + Operand::BrS { offset } => { // a short branch `disp` bytes forward - write!(f, "$+{}", disp) + write!(f, "$+{:#x}", offset) + } + Operand::BrB { offset } => { + // a branch by signed `offset` bytes + if *offset < 0 { + write!(f, "$-{:#x}", -offset) + } else { + write!(f, "$+{:#x}", offset) + } + } + Operand::BrW { offset } => { + // a branch by signed `offset` bytes + if *offset < 0 { + write!(f, "$-{:#x}", -offset) + } else { + write!(f, "$+{:#x}", offset) + } } Operand::BrA { offset } => { // a branch by signed `offset` bytes - write!(f, "$+{}", offset) + if *offset < 0 { + write!(f, "$-{:#x}", -offset) + } else { + write!(f, "$+{:#x}", offset) + } } Operand::ImmB { imm } => { - write!(f, "#{}", imm) + write!(f, "#{:x}h", imm) } Operand::ImmW { imm } => { - write!(f, "#{}", imm) + write!(f, "#{:x}h", imm) } Operand::ImmL { imm } => { - write!(f, "#{}", imm) + write!(f, "#{:x}h", imm) } } } @@ -860,11 +967,11 @@ trait DecodeHandler::Address, ::Word>> { Operand::Deref { gpr: rs, disp: 0, width: size } }, 0b01 => { - let disp = self.read_u8(words)? as u32; + let disp = self.read_u8(words)? as u32 * size.bytes() as u32; Operand::Deref { gpr: rs, disp, width: size } } 0b10 => { - let disp = self.read_u16(words)? as u32; + let disp = self.read_u16(words)? as u32 * size.bytes() as u32; Operand::Deref { gpr: rs, disp, width: size } } _ => { @@ -1018,8 +1125,8 @@ fn decode_inst< } else if opc < 0b0001_0000 { handler.on_opcode_decoded(Opcode::BRA)?; let disp = opc & 0b111; - // TODO: double-check the displacement offset thingy - handler.on_operand_decoded(0, Operand::BrS(disp))?; + let offset = if disp < 0b11 { disp + 8 } else { disp }; + handler.on_operand_decoded(0, Operand::BrS { offset })?; } else if opc < 0b0010_0000 { handler.on_opcode_decoded(if opc & 0b0000_1000 == 0 { Opcode::BEQ @@ -1027,8 +1134,8 @@ fn decode_inst< Opcode::BNE })?; let disp = opc & 0b111; - // TODO: double-check the displacement offset thingy - handler.on_operand_decoded(0, Operand::BrS(disp))?; + let offset = if disp < 0b11 { disp + 8 } else { disp }; + handler.on_operand_decoded(0, Operand::BrS { offset })?; } else if opc < 0b0011_0000 { // BCnd.B let cond = opc & 0b1111; @@ -1039,7 +1146,11 @@ fn decode_inst< Opcode::BO, Opcode::BNO, Opcode::BRA, /* no branch for cnd=1111 */ ]; - if let Some(op) = OPC_TABLE.get(cond as usize) { + if cond == 0b1110 { + handler.on_opcode_decoded(Opcode::BRA)?; + let imm = handler.read_u8(words)?; + handler.on_operand_decoded(0, Operand::BrB { offset: imm as i8 })?; + } else if let Some(op) = OPC_TABLE.get(cond as usize) { handler.on_opcode_decoded(*op)?; let imm = handler.read_u8(words)?; handler.on_operand_decoded(0, Operand::ImmB { imm })?; @@ -1051,7 +1162,7 @@ fn decode_inst< } else if opc == 0b0011_1000 { handler.on_opcode_decoded(Opcode::BRA)?; let imm = handler.read_u16(words)?; - handler.on_operand_decoded(0, Operand::ImmW { imm })?; + handler.on_operand_decoded(0, Operand::BrW { offset: imm as i16 })?; } else if opc == 0b0011_1001 { handler.on_opcode_decoded(Opcode::BSR)?; let imm = handler.read_u16(words)?; @@ -1074,15 +1185,15 @@ fn decode_inst< match opc & 0b11 { 0b00 => { handler.on_operand_decoded(0, Operand::ImmB { imm: imm as u8 })?; - handler.on_operand_decoded(1, Operand::Deref { gpr: rd, disp, width: SizeCode::B })?; + handler.on_operand_decoded(1, Operand::Deref { gpr: rd, disp: disp * 1, width: SizeCode::B })?; } 0b01 => { handler.on_operand_decoded(0, Operand::ImmW { imm: imm as u8 as u16 })?; - handler.on_operand_decoded(1, Operand::Deref { gpr: rd, disp, width: SizeCode::W })?; + handler.on_operand_decoded(1, Operand::Deref { gpr: rd, disp: disp * 2, width: SizeCode::W })?; } 0b10 => { handler.on_operand_decoded(0, Operand::ImmL { imm: imm as u8 as u32 })?; - handler.on_operand_decoded(1, Operand::Deref { gpr: rd, disp, width: SizeCode::L })?; + handler.on_operand_decoded(1, Operand::Deref { gpr: rd, disp: disp * 4, width: SizeCode::L })?; } _ => { unreachable!("sz=11 is rtsd") } }; @@ -1126,6 +1237,11 @@ fn decode_inst< handler.on_opcode_decoded(Opcode::RTSD)?; handler.on_operand_decoded(0, Operand::ImmB { imm: operands })?; } else { + let opcode = [ + Opcode::SUB, Opcode::CMP, Opcode::ADD, Opcode::MUL, + Opcode::AND, Opcode::OR, Opcode::MOV + ][opc as usize]; + handler.on_opcode_decoded(opcode)?; let imm = operands >> 4; let rd = operands & 0b1111; handler.on_operand_decoded(0, Operand::ImmB { imm })?; @@ -1516,7 +1632,7 @@ fn decode_inst< let dispmid = (operands >> 6) & 2; let disphi = (opc & 0b111) << 2; let disp = displo | dispmid | disphi; - handler.on_operand_decoded(0, Operand::Deref { gpr: rs, disp: disp as u32, width: sz })?; + handler.on_operand_decoded(0, Operand::Deref { gpr: rs, disp: disp as u32 * sz.bytes() as u32, width: sz })?; handler.on_operand_decoded(1, Operand::Register { num: rd })?; } else { handler.on_opcode_decoded(Opcode::MOV)?; @@ -1533,9 +1649,12 @@ fn decode_inst< let disp = displo | dispmid | disphi; if opc & 0b0000_1000 == 0 { handler.on_operand_decoded(0, Operand::Register { num: rs })?; - handler.on_operand_decoded(1, Operand::Deref { gpr: rd, disp: disp as u32, width: sz })?; + handler.on_operand_decoded(1, Operand::Deref { gpr: rd, disp: disp as u32 * sz.bytes() as u32, width: sz })?; } else { - handler.on_operand_decoded(0, Operand::Deref { gpr: rs, disp: disp as u32, width: sz })?; + // also swaps the meaning of the rs/rd fields in this encoding + let rs = (operands >> 4) & 0b111; + let rd = operands & 0b111; + handler.on_operand_decoded(0, Operand::Deref { gpr: rs, disp: disp as u32 * sz.bytes() as u32, width: sz })?; handler.on_operand_decoded(1, Operand::Register { num: rd })?; } } else { -- cgit v1.1