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fd080b323c
This guarantees the bitfield is 5 bits, so if someone in the future decides to shift bits around in the struct it wont break Ballistic. Signed-off-by: Ronald Caesar <github43132@proton.me>
94 lines
2.8 KiB
C
94 lines
2.8 KiB
C
/**
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* @file bal_decoder.h
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* @brief ARM Instruction Decoder Interface.
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*
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* @details
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* This module provides the interface for decoding ARM instructions.
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*/
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#ifndef BAL_DECODER_H
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#define BAL_DECODER_H
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#include "bal_attributes.h"
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#include "bal_types.h"
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#include <assert.h>
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#include <stdint.h>
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#ifdef __cplusplus
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extern "C"
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{
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#endif
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#define BAL_OPERAND_BIT_WIDTH 5
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/// The type of an instruction operand.
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typedef enum
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{
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BAL_OPERAND_TYPE_NONE = 0,
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BAL_OPERAND_TYPE_REGISTER_32 = 1,
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BAL_OPERAND_TYPE_REGISTER_64 = 2,
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BAL_OPERAND_TYPE_REGISTER_128 = 3,
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BAL_OPERAND_TYPE_IMMEDIATE = 4,
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BAL_OPERAND_TYPE_CONDITION = 5,
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} bal_decoder_operand_type_t;
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/// Descriptor for a single operand.
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typedef struct
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{
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/// Operand type. See [`bal_decoder_operand_type_t`].
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uint16_t type : 5;
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/// Bit position in the instruction.
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uint16_t bit_position : 6;
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/// Bit width of the field.
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uint16_t bit_width : BAL_OPERAND_BIT_WIDTH;
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} bal_decoder_operand_t;
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static_assert(2 == sizeof(bal_decoder_operand_t), "Expected operand struct to be 2 bytes.");
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static_assert(5 == BAL_OPERAND_BIT_WIDTH, "Operand bit width must be less than 32 to prevent shift overflow.");
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/// Represents static metadata aasociated with a specific ARM instruction.
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BAL_ALIGNED(32) typedef struct
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{
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/// The instruction mnemonic.
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const char *name;
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/// A bitmask indicating which bits in the instruction word are
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/// significant for decoding.
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///
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/// A value of `1` indicates a fixed bit used for identification,
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/// while `0` indicates a variable field (e.g, imm, shamt, Rn).
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uint32_t mask;
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/// The expected pattern of the instruction after applying the `mask`.
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/// `(instruction & mask) == expected`.
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uint32_t expected;
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/// The IR opcode equivalent to this instruction's mnemonic.
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bal_opcode_t ir_opcode;
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/// Descriptors for up to 4 operands.
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bal_decoder_operand_t operand[4];
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} bal_decoder_instruction_metadata_t;
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static_assert(32 == sizeof(bal_decoder_instruction_metadata_t), "Expected decoder metadata struct to be 32 bytes.");
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/// Decodes a raw ARM64 instruction.
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///
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/// Returns a pointer to [`bal_decoder_instruction_metadata_t`] describing
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/// the instruction if a match is found, or `NULL` if the instruction is
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/// invalid.
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///
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/// # Safety
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///
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/// The pointer refers to static readonly memory. It is valid for the
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/// lifetime of the program and must not be freed.
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BAL_HOT const bal_decoder_instruction_metadata_t *bal_decoder_arm64_decode(
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const uint32_t instruction);
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#ifdef __cplusplus
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}
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#endif
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#endif // POUND_JIT_DECODER_ARM32_H
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