Module shift 

Variable-amount shift gadgets.

CircuitBuilder only exposes shifts by a compile-time-constant amount. This module provides barrel-shifter gadgets that shift by a runtime Wire amount:

• var_sll, var_srl, var_sra — shift by the low 6 bits of shift (full bit range for a 64-bit word).
• var_sll_blocks, var_srl_blocks, var_sra_blocks — most general: the actual bit-shift is shift * 2^block_bits, with shift treated as a shift_bits-bit unsigned integer. Useful when the caller knows the shift is a multiple of a fixed power of two, or when only a narrow range of shifts is possible.
• var_sll_bytes, var_srl_bytes, var_sra_bytes — byte-granularity shifts (shift in 0..8 bytes).

Precondition

For *_blocks, the shift amount is treated as a shift_bits-bit unsigned integer; bits above position shift_bits - 1 are ignored. Callers must ensure shift < 2^shift_bits; this is not checked by the gadget. The other variants impose the same precondition with shift_bits fixed (6 for the base variants, 3 for the byte variants).

Cost

*_blocks: 3 * shift_bits AND constraints. Base variants: 18. Byte variants: 9.

Functions

var_sll

Variable-amount logical left shift.

var_sll_blocks

Variable-amount logical left shift by blocks of 2^block_bits bits.

var_sll_bytes

Variable-amount logical left shift by whole bytes.

var_sra

Variable-amount arithmetic right shift.

var_sra_blocks

Variable-amount arithmetic right shift by blocks of 2^block_bits bits.

var_sra_bytes

Variable-amount arithmetic right shift by whole bytes.

var_srl

Variable-amount logical right shift.

var_srl_blocks

Variable-amount logical right shift by blocks of 2^block_bits bits.

var_srl_bytes

Variable-amount logical right shift by whole bytes.