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https://github.com/logos-storage/plonky2.git
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997453237f
Ultimately they're encoded as `[F; 8]`s in the table, but I don't anticipate that we'll have any use cases where we want to store more than 256 bits. Might as well store `U256` until we actually build the table since they're more compact.
44 lines
1.9 KiB
Rust
44 lines
1.9 KiB
Rust
//! Memory registers.
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use crate::memory::{NUM_CHANNELS, VALUE_LIMBS};
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// Columns for memory operations, ordered by (addr, timestamp).
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pub(crate) const TIMESTAMP: usize = 0;
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pub(crate) const IS_READ: usize = TIMESTAMP + 1;
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pub(crate) const ADDR_CONTEXT: usize = IS_READ + 1;
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pub(crate) const ADDR_SEGMENT: usize = ADDR_CONTEXT + 1;
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pub(crate) const ADDR_VIRTUAL: usize = ADDR_SEGMENT + 1;
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// Eight 32-bit limbs hold a total of 256 bits.
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// If a value represents an integer, it is little-endian encoded.
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const VALUE_START: usize = ADDR_VIRTUAL + 1;
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pub(crate) const fn value_limb(i: usize) -> usize {
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debug_assert!(i < VALUE_LIMBS);
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VALUE_START + i
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}
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// Flags to indicate whether this part of the address differs from the next row,
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// and the previous parts do not differ.
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// That is, e.g., `SEGMENT_FIRST_CHANGE` is `F::ONE` iff `ADDR_CONTEXT` is the same in this
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// row and the next, but `ADDR_SEGMENT` is not.
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pub(crate) const CONTEXT_FIRST_CHANGE: usize = VALUE_START + VALUE_LIMBS;
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pub(crate) const SEGMENT_FIRST_CHANGE: usize = CONTEXT_FIRST_CHANGE + 1;
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pub(crate) const VIRTUAL_FIRST_CHANGE: usize = SEGMENT_FIRST_CHANGE + 1;
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// Flags to indicate if this operation came from the `i`th channel of the memory bus.
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const IS_CHANNEL_START: usize = VIRTUAL_FIRST_CHANGE + 1;
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pub(crate) const fn is_channel(channel: usize) -> usize {
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debug_assert!(channel < NUM_CHANNELS);
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IS_CHANNEL_START + channel
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}
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// We use a range check to enforce the ordering.
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pub(crate) const RANGE_CHECK: usize = IS_CHANNEL_START + NUM_CHANNELS;
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// The counter column (used for the range check) starts from 0 and increments.
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pub(crate) const COUNTER: usize = RANGE_CHECK + 1;
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// Helper columns for the permutation argument used to enforce the range check.
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pub(crate) const RANGE_CHECK_PERMUTED: usize = COUNTER + 1;
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pub(crate) const COUNTER_PERMUTED: usize = RANGE_CHECK_PERMUTED + 1;
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pub(crate) const NUM_COLUMNS: usize = COUNTER_PERMUTED + 1;
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