1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
|
// 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::{assert_or_err, Error, Result};
use crate::arm32::{
ArmOpcode,
Instruction,
InstructionCodec,
Shifter,
};
use core::num::Wrapping;
fn add_shifter(mut opcode: u32, shifter: Shifter) -> Result<u32> {
use Shifter::*;
let get_shift_code = |shifter: Shifter| match shifter {
LogicalShiftLeftImmediate { .. } => 0b00,
LogicalShiftRightImmediate { .. } => 0b01,
ArithmeticShiftRightImmediate { .. } => 0b10,
RotateRightImmediate { .. } => 0b11,
_ => panic!("cannot get shifter code of `{shifter:?}`"),
};
match shifter {
LogicalShiftLeftImmediate { source, shift: 0x0 }
=> {
opcode |= source as u32;
}
| ArithmeticShiftRightImmediate { source, shift }
| LogicalShiftLeftImmediate { source, shift }
| LogicalShiftRightImmediate { source, shift }
| RotateRightImmediate { source, shift }
=> {
assert_or_err!(shift != 0x0, Error::IllegalImmediate { reason: "immediate shift cannot be null on arm" });
let code = get_shift_code(shifter);
opcode |= source as u32;
opcode |= code << 0x5;
opcode |= shift << 0x7;
}
RotateRightExtend { .. } => {
todo!()
}
| ArithmeticShiftRightRegister { source, .. }
| LogicalShiftLeftRegister { source, .. }
| LogicalShiftRightRegister { source, .. }
| RotateRightRegister { source, .. }
=> {
let _code = get_shift_code(shifter);
opcode |= 0b00000000_00000000_00000000_00010000;
opcode |= source as u32;
}
Immediate(source) => {
let (source, rotate) = if source <= 0xFF {
(source, 0x00)
} else {
todo!()
};
opcode |= 0b00000010_00000000_00000000_00000000;
opcode |= source;
opcode |= rotate << 0x8;
}
}
Ok(opcode)
}
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_u32;
match instruction {
Branch {
predicate,
..
} => {
opcode |= 0b00001011_00000000_00000000_00000000;
opcode |= (predicate as u32) << 0x1C;
}
BranchExchange {
predicate,
source,
} => {
opcode |= 0b00000001_00101111_11111111_00010000;
opcode |= source as u32;
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.skip_words(0x1);
Ok(opcode.into())
}
}
|
