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authorAleksandar Markovic <amarkovic@wavecomp.com>2018-12-25 15:55:09 +0100
committerAleksandar Markovic <amarkovic@wavecomp.com>2019-01-03 17:52:52 +0100
commitafd47cef11f84b070d760f2270c291df6e762151 (patch)
tree2f0e628b40d3325f7122725a0c2d9fa802dde37e /disas/nanomips.cpp
parent9980a2251338922e53911a0fded21147b9ca0175 (diff)
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>
Diffstat (limited to 'disas/nanomips.cpp')
-rw-r--r--disas/nanomips.cpp27
1 files changed, 27 insertions, 0 deletions
diff --git a/disas/nanomips.cpp b/disas/nanomips.cpp
index 66b1223f48..de96125186 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,