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Diffstat (limited to 'src/arm32/instruction_codec/encode_arm.rs')
-rw-r--r-- | src/arm32/instruction_codec/encode_arm.rs | 138 |
1 files changed, 138 insertions, 0 deletions
diff --git a/src/arm32/instruction_codec/encode_arm.rs b/src/arm32/instruction_codec/encode_arm.rs new file mode 100644 index 0000000..73dc3d9 --- /dev/null +++ b/src/arm32/instruction_codec/encode_arm.rs @@ -0,0 +1,138 @@ +// Copyright 2024 Gabriel Bjørnager Jensen. +// +// This file is part of Pollex. +// +// Pollex is free software: you can redistribute it +// and/or modify it under the terms of the GNU Af- +// fero General Public License as published by the +// Free Software Foundation, either version 3 of +// the License, or (at your option) any later ver- +// sion. +// +// Pollex is distributed in the hope that it will +// be useful, but WITHOUT ANY WARRANTY; without +// even the implied warranty of MERCHANTABILITY or +// FITNESS FOR A PARTICULAR PURPOSE. See the GNU +// Affero General Public License for more details. +// +// You should have received a copy of the GNU Af- +// fero General Public License along with Pollex. +// If not, see <https://www.gnu.org/licenses/>. + +use crate::Result; +use crate::arm32::{ + ArmOpcode, + Instruction, + InstructionCodec, + Shifter, +}; + +impl InstructionCodec { + /// Encodes the given Arm instruction. + /// + /// # Errors + /// + /// If the operands of the provided instruction cannot be encoded in the given combination, or are incompatible with the mnemonic, an error is returned. + pub fn encode_arm(&mut self, instruction: Instruction) -> Result<ArmOpcode> { + use Instruction::*; + + let mut opcode = 0b00000000_00000000_00000000_00000000; + + match instruction { + Branch { predicate, .. } => { + opcode |= 0b00001011_00000000_00000000_00000000; + opcode |= (predicate as u32) << 0x1C; + }, + + BranchLink { predicate, .. } => { + opcode |= 0b00001010_00000000_00000000_00000000; + opcode |= (predicate as u32) << 0x1C; + }, + + Breakpoint { immediate } => { + opcode |= 0b11100001_00100000_00000000_01110000; + opcode |= immediate & 0b00000000_00000000_00000000_00001111; + opcode |= (immediate & 0b00000000_00000000_11111111_11110000) << 0x4; + }, + + Move { predicate, destination, source, s } => { + opcode |= 0b00000001_10100000_00000000_00000000; + opcode |= (destination as u32) << 0xC; + opcode |= u32::from(s) << 0x14; + opcode |= (predicate as u32) << 0x1C; + + opcode = add_shifter(opcode, source); + }, + + SoftwareInterrupt { predicate, immediate } => { + opcode |= 0b00001111_00000000_00000000_00000000; + opcode |= immediate & 0b00000000_11111111_11111111_11111111; + opcode |= (predicate as u32) << 0x1C; + }, + + _ => todo!(), + } + + self.address += ArmOpcode::SIZE; + Ok(opcode.into()) + } +} + +fn add_shifter(mut opcode: u32, shifter: Shifter) -> u32 { + match shifter { + | Shifter::ArithmeticShiftRightImmediate { source, shift } + | Shifter::LogicalShiftLeftImmediate { source, shift } + | Shifter::LogicalShiftRightImmediate { source, shift } + | Shifter::RotateRightImmediate { source, shift } + => { + let code = match shifter { + Shifter::LogicalShiftLeftImmediate { .. } => 0b00, + Shifter::LogicalShiftRightImmediate { .. } => 0b01, + Shifter::ArithmeticShiftRightImmediate { .. } => 0b10, + Shifter::RotateRightImmediate { .. } => 0b11, + + _ => unreachable!(), + }; + + opcode |= source as u32; + opcode |= code << 0x5; + opcode |= shift << 0x7; + }, + + Shifter::RotateRightExtend { .. } => { + todo!() + }, + + | Shifter::ArithmeticShiftRightRegister { source, .. } + | Shifter::LogicalShiftLeftRegister { source, .. } + | Shifter::LogicalShiftRightRegister { source, .. } + | Shifter::RotateRightRegister { source, .. } + => { + let _code = match shifter { + Shifter::LogicalShiftLeftRegister { .. } => 0b00, + Shifter::LogicalShiftRightRegister { .. } => 0b01, + Shifter::ArithmeticShiftRightRegister { .. } => 0b10, + Shifter::RotateRightRegister { .. } => 0b11, + + _ => unreachable!(), + }; + + opcode |= 0b00000000_00000000_00000000_00010000; + opcode |= source as u32; + }, + + Shifter::Immediate { immediate } => { + let (immediate, rotate) = if immediate <= 0xFF { + (immediate, 0x00) + } else { + todo!() + }; + + opcode |= 0b00000010_00000000_00000000_00000000; + opcode |= immediate; + opcode |= rotate << 0x8; + }, + } + + opcode +} |