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//! VM parameters

use fuel_types::{
    AssetId,
    Bytes32,
    Word,
};

use core::mem;

/// Register count for checking constraints
pub const VM_REGISTER_COUNT: usize = 64;

/// The number of readable registers.
pub const VM_REGISTER_SYSTEM_COUNT: usize = 16;

/// The number of writable registers.
pub const VM_REGISTER_PROGRAM_COUNT: usize = VM_REGISTER_COUNT - VM_REGISTER_SYSTEM_COUNT;

// MEMORY TYPES

/// Length of a word, in bytes
pub const WORD_SIZE: usize = mem::size_of::<Word>();

/// Maximum memory in MiB
pub const FUEL_MAX_MEMORY_SIZE: u64 = 64;

/// Maximum VM RAM, in bytes.
pub const VM_MAX_RAM: u64 = 1024 * 1024 * FUEL_MAX_MEMORY_SIZE;

/// Size of the VM memory, in bytes.
#[allow(clippy::cast_possible_truncation)]
pub const MEM_SIZE: usize = VM_MAX_RAM as usize;

static_assertions::const_assert!(VM_MAX_RAM < usize::MAX as u64);

// no limits to heap for now.

/// Offset for the assets balances in VM memory
pub const VM_MEMORY_BASE_ASSET_ID_OFFSET: usize = Bytes32::LEN;

/// Offset for the assets balances in VM memory
pub const VM_MEMORY_BALANCES_OFFSET: usize =
    VM_MEMORY_BASE_ASSET_ID_OFFSET + AssetId::LEN;

/// Encoded len of a register id in an instruction (unused)
pub const VM_REGISTER_WIDTH: u8 = 6;

/// Empty merkle root for receipts tree
pub const EMPTY_RECEIPTS_MERKLE_ROOT: [u8; 32] = [
    0xe3, 0xb0, 0xc4, 0x42, 0x98, 0xfc, 0x1c, 0x14, 0x9a, 0xfb, 0xf4, 0xc8, 0x99, 0x6f,
    0xb9, 0x24, 0x27, 0xae, 0x41, 0xe4, 0x64, 0x9b, 0x93, 0x4c, 0xa4, 0x95, 0x99, 0x1b,
    0x78, 0x52, 0xb8, 0x55,
];