17 Signed Immediates for I- and S-Type Instructions

All I- and S-type instructions with 12-bit signed immediates --- e.g., addi but not slli --- accept their immediate argument as an integer in the interval [-2048, 2047]. Integers in the subinterval [-2048, -1] can also be passed by their (unsigned) associates in the interval [0xfffff800, 0xffffffff] on RV32I, and in [0xfffffffffffff800, 0xffffffffffffffff] on both RV32I and RV64I.