memory.cpp

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#include "barretenberg/vm2/simulation/gadgets/memory.hpp"
 
#include <cstdint>
 
#include "barretenberg/common/log.hpp"
#include "barretenberg/numeric/uint128/uint128.hpp"
#include "barretenberg/vm2/common/memory_types.hpp"
 
namespace bb::avm2::simulation {
 
namespace {
 
// Default value for uninitialized memory: FF(0) with tag FF.
const auto DEFAULT_MEM_VALUE = MemoryValue::from_tag(MemoryTag::FF, 0);
 
} // namespace
 
void Memory::set(MemoryAddress index, MemoryValue value)
{
    // Improvement: reconsider tag validation strategy.
    validate_tag(value);
    memory[index] = value;
    debug("Memory write: ", index, " <- ", value.to_string());
    events.emit({ .execution_clk = execution_id_manager.get_execution_id(),
                  .mode = MemoryMode::WRITE,
                  .addr = index,
                  .value = value,
                  .space_id = space_id });
}
 
const MemoryValue& Memory::get(MemoryAddress index) const
{
    auto it = memory.find(index);
    const auto& vt = it != memory.end() ? it->second : DEFAULT_MEM_VALUE;
    events.emit({ .execution_clk = execution_id_manager.get_execution_id(),
                  .mode = MemoryMode::READ,
                  .addr = index,
                  .value = vt,
                  .space_id = space_id });
 
    debug("Memory read: ", index, " -> ", vt.to_string());
    return vt;
}
 
const MemoryValue& Memory::unconstrained_get(MemoryAddress index) const
{
    auto it = memory.find(index);
    return it != memory.end() ? it->second : DEFAULT_MEM_VALUE;
}
 
void Memory::validate_tag(const MemoryValue& value) const
{
    if (value.get_tag() == MemoryTag::FF) {
        return;
    }
 
    uint128_t value_as_uint128 = static_cast<uint128_t>(value.as_ff());
    uint8_t tag_bits = get_tag_bits(value.get_tag());
    range_check.assert_range(value_as_uint128, tag_bits);
}
 
} // namespace bb::avm2::simulation