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 <arikalo@wavecomp.com>
Signed-off-by: Aleksandar Markovic <amarkovic@wavecomp.com>
stable-4.0
Aleksandar Markovic 2018-12-25 15:55:09 +01:00
parent 9980a22513
commit afd47cef11
1 changed files with 27 additions and 0 deletions

View File

@ -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,