From afd47cef11f84b070d760f2270c291df6e762151 Mon Sep 17 00:00:00 2001 From: Aleksandar Markovic Date: Tue, 25 Dec 2018 15:55:09 +0100 Subject: disas: nanoMIPS: Comment the decoder of 'gpr4.zero' gpr encoding type Comment the decoder of 'gpr4.zero' gpr encoding type in nanoMIPS disassembler. Reviewed-by: Aleksandar Rikalo Signed-off-by: Aleksandar Markovic --- disas/nanomips.cpp | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) diff --git a/disas/nanomips.cpp b/disas/nanomips.cpp index 66b1223..de96125 100644 --- a/disas/nanomips.cpp +++ b/disas/nanomips.cpp @@ -397,6 +397,33 @@ uint64 NMD::encode_rd1_from_rd(uint64 d) } +/* + * NMD::decode_gpr_gpr4_zero() - decoder for 'gpr4.zero' gpr encoding type + * + * Map a 4-bit code to the 5-bit register space according to this pattern: + * + * 1 0 + * 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 + * | | | | | | | | | | | | | | | | + * | | | | | | | | | | | | └---------------------┐ + * | | | | | | | | | | | └---------------┐ | + * | | | | | | | | | | └---------------┐ | | + * | | | | | | | | | └---------------┐ | | | + * | | | | | | | | └---------------┐ | | | | + * | | | | | | | | | | | | | | | | + * | | | | | | | | | | | | | | | | + * 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 + * 3 2 1 0 + * + * This pattern is the same one used for 'gpr4' gpr encoding type, except for + * the input value 3, that is mapped to the output value 0 instead of 11. + * + * Used in handling following instructions: + * + * - MOVE.BALC + * - MOVEP + * - SW[4X4] + */ uint64 NMD::decode_gpr_gpr4_zero(uint64 d) { static uint64 register_list[] = { 8, 9, 10, 0, 4, 5, 6, 7, -- cgit v1.1