From 01fc2557ca59c86b6583724ea1952dc2ee271a57 Mon Sep 17 00:00:00 2001 From: Aleksandar Markovic Date: Tue, 25 Dec 2018 15:06:15 +0100 Subject: disas: nanoMIPS: Comment the decoder of 'gpr3' gpr encoding type Comment the decoder of 'gpr3' gpr encoding type in nanoMIPS disassembler. Reviewed-by: Aleksandar Rikalo Signed-off-by: Aleksandar Markovic --- disas/nanomips.cpp | 51 ++++++++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 48 insertions(+), 3 deletions(-) diff --git a/disas/nanomips.cpp b/disas/nanomips.cpp index 2856645..30988f8 100644 --- a/disas/nanomips.cpp +++ b/disas/nanomips.cpp @@ -292,9 +292,54 @@ uint64 NMD::renumber_registers(uint64 index, uint64 *register_list, /* - * these functions should be decode functions but the json does not have - * decode sections so they are based on the encode, the equivalent decode - * functions need writing eventually. + * NMD::decode_gpr_gpr3() - decoder for 'gpr3' gpr encoding type + * + * Map a 3-bit code to the 5-bit register space according to this pattern: + * + * 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 + * + * Used in handling following instructions: + * + * - ADDIU[R1.SP] + * - ADDIU[R2] + * - ADDU[16] + * - AND[16] + * - ANDI[16] + * - BEQC[16] + * - BEQZC[16] + * - BNEC[16] + * - BNEZC[16] + * - LB[16] + * - LBU[16] + * - LH[16] + * - LHU[16] + * - LI[16] + * - LW[16] + * - LW[GP16] + * - LWXS[16] + * - NOT[16] + * - OR[16] + * - SB[16] + * - SH[16] + * - SLL[16] + * - SRL[16] + * - SUBU[16] + * - SW[16] + * - XOR[16] */ uint64 NMD::decode_gpr_gpr3(uint64 d) { -- cgit v1.1