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https://github.com/logos-storage/plonky2.git
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645d45f227
* Column definitions for addition, range checks & lookups I implemented addition (unsigned for now) as an example of how the arithmetic unit can interact with the 16-bit range check unit. Range checks and lookups aren't implemented yet. * Missing constraints * Tweaks to get tests passing * Reorg registers into files * Minor
38 lines
1.8 KiB
Rust
38 lines
1.8 KiB
Rust
//! Arithmetic unit.
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pub(crate) const IS_ADD: usize = super::START_ARITHMETIC;
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pub(crate) const IS_SUB: usize = IS_ADD + 1;
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pub(crate) const IS_MUL: usize = IS_SUB + 1;
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pub(crate) const IS_DIV: usize = IS_MUL + 1;
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const START_SHARED_COLS: usize = IS_DIV + 1;
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/// Within the arithmetic unit, there are shared columns which can be used by any arithmetic
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/// circuit, depending on which one is active this cycle.
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// Can be increased as needed as other operations are implemented.
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const NUM_SHARED_COLS: usize = 3;
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const fn shared_col(i: usize) -> usize {
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debug_assert!(i < NUM_SHARED_COLS);
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START_SHARED_COLS + i
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}
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/// The first value to be added; treated as an unsigned u32.
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pub(crate) const COL_ADD_INPUT_1: usize = shared_col(0);
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/// The second value to be added; treated as an unsigned u32.
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pub(crate) const COL_ADD_INPUT_2: usize = shared_col(1);
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/// The third value to be added; treated as an unsigned u32.
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pub(crate) const COL_ADD_INPUT_3: usize = shared_col(2);
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// Note: Addition outputs three 16-bit chunks, and since these values need to be range-checked
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// anyway, we might as well use the range check unit's columns as our addition outputs. So the
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// three proceeding columns are basically aliases, not columns owned by the arithmetic unit.
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/// The first 16-bit chunk of the output, based on little-endian ordering.
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pub(crate) const COL_ADD_OUTPUT_1: usize = super::range_check_16::col_rc_16_input(0);
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/// The second 16-bit chunk of the output, based on little-endian ordering.
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pub(crate) const COL_ADD_OUTPUT_2: usize = super::range_check_16::col_rc_16_input(1);
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/// The third 16-bit chunk of the output, based on little-endian ordering.
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pub(crate) const COL_ADD_OUTPUT_3: usize = super::range_check_16::col_rc_16_input(2);
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pub(super) const END: usize = super::START_ARITHMETIC + NUM_SHARED_COLS;
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