cairo_lang_casm/
encoder.rs

1#[cfg(not(feature = "std"))]
2use alloc::{vec, vec::Vec};
3
4use num_bigint::BigInt;
5
6use crate::assembler::{ApUpdate, FpUpdate, InstructionRepr, Op1Addr, Opcode, PcUpdate, Res};
7use crate::operand::Register;
8
9#[cfg(test)]
10#[path = "encoder_test.rs"]
11mod test;
12
13const OFFSET_BITS: u32 = 16;
14
15const DST_REG_BIT: i32 = 0;
16const OP0_REG_BIT: i32 = 1;
17const OP1_IMM_BIT: i32 = 2;
18const OP1_FP_BIT: i32 = 3;
19const OP1_AP_BIT: i32 = 4;
20const RES_ADD_BIT: i32 = 5;
21const RES_MUL_BIT: i32 = 6;
22const PC_JUMP_ABS_BIT: i32 = 7;
23const PC_JUMP_REL_BIT: i32 = 8;
24const PC_JNZ_BIT: i32 = 9;
25const AP_ADD_BIT: i32 = 10;
26const AP_ADD1_BIT: i32 = 11;
27const OPCODE_CALL_BIT: i32 = 12;
28const OPCODE_RET_BIT: i32 = 13;
29const OPCODE_ASSERT_EQ_BIT: i32 = 14;
30
31impl InstructionRepr {
32    pub fn encode(&self) -> Vec<BigInt> {
33        // Convert the offsets from possibly negative numbers in the range [-2^15, 2^15)
34        // to positive numbers in the range [0, 2^16) centered around 2^15.
35        let off0_enc: u64 = ((self.off0 as i32) + (1 << (OFFSET_BITS - 1))) as u64;
36        let off1_enc: u64 = ((self.off1 as i32) + (1 << (OFFSET_BITS - 1))) as u64;
37        let off2_enc: u64 = ((self.off2 as i32) + (1 << (OFFSET_BITS - 1))) as u64;
38
39        let mut flags = 0;
40        if self.dst_register == Register::FP {
41            flags |= 1 << DST_REG_BIT;
42        }
43        if self.op0_register == Register::FP {
44            flags |= 1 << OP0_REG_BIT;
45        }
46        assert_eq!(
47            self.imm.is_some(),
48            self.op1_addr == Op1Addr::Imm,
49            "Immediate must appear iff op1_addr is Op1Addr.IMM"
50        );
51        flags |= match self.op1_addr {
52            Op1Addr::Imm => 1 << OP1_IMM_BIT,
53            Op1Addr::AP => 1 << OP1_AP_BIT,
54            Op1Addr::FP => 1 << OP1_FP_BIT,
55            Op1Addr::Op0 => 0,
56        };
57
58        flags |= match self.res {
59            Res::Add => 1 << RES_ADD_BIT,
60            Res::Mul => 1 << RES_MUL_BIT,
61            Res::Op1 => 0,
62            Res::Unconstrained => 0,
63        };
64
65        assert_eq!(
66            self.res == Res::Unconstrained,
67            self.pc_update == PcUpdate::Jnz,
68            "res must be Unconstrained iff pc_update is Jnz"
69        );
70
71        flags |= match self.pc_update {
72            PcUpdate::Jump => 1 << PC_JUMP_ABS_BIT,
73            PcUpdate::JumpRel => 1 << PC_JUMP_REL_BIT,
74            PcUpdate::Jnz => 1 << PC_JNZ_BIT,
75            PcUpdate::Regular => 0,
76        };
77
78        assert_eq!(
79            self.ap_update == ApUpdate::Add2,
80            self.opcode == Opcode::Call,
81            "ap_update is Add2 iff opcode is Call"
82        );
83
84        flags |= match self.ap_update {
85            ApUpdate::Add => 1 << AP_ADD_BIT,
86            ApUpdate::Add1 => 1 << AP_ADD1_BIT,
87            ApUpdate::Add2 => 0,
88            ApUpdate::Regular => 0,
89        };
90
91        assert_eq!(
92            self.fp_update,
93            match self.opcode {
94                Opcode::Nop => FpUpdate::Regular,
95                Opcode::Call => FpUpdate::ApPlus2,
96                Opcode::Ret => FpUpdate::Dst,
97                Opcode::AssertEq => FpUpdate::Regular,
98            },
99            "fp_update {:?} does not match opcode {:?}.",
100            self.fp_update,
101            self.opcode
102        );
103
104        flags |= match self.opcode {
105            Opcode::Call => 1 << OPCODE_CALL_BIT,
106            Opcode::Ret => 1 << OPCODE_RET_BIT,
107            Opcode::AssertEq => 1 << OPCODE_ASSERT_EQ_BIT,
108            Opcode::Nop => 0,
109        };
110
111        let mut encoding: u64 = flags << (3 * OFFSET_BITS);
112        encoding |= off2_enc << (2 * OFFSET_BITS);
113        encoding |= off1_enc << (OFFSET_BITS);
114        encoding |= off0_enc;
115
116        let bigint_encoding = BigInt::from(encoding);
117        if let Some(imm) = self.imm.clone() {
118            vec![bigint_encoding, imm]
119        } else {
120            vec![bigint_encoding]
121        }
122    }
123}
cairo_lang_casm/encoder.rs

cairo_lang_casm/
encoder.rs
