From: Jacob Lifshay <programmerjake@gmail.com>
Date: Tue, 18 Apr 2023 04:26:43 +0000 (-0700)
Subject: add shaddw
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=5e7b3c2dd8b5aba121a3c1305a6a663efc322e6c;p=libreriscv.git

add shaddw
---

diff --git a/openpower/sv/bitmanip.mdwn b/openpower/sv/bitmanip.mdwn
index c83965590..59688e129 100644
--- a/openpower/sv/bitmanip.mdwn
+++ b/openpower/sv/bitmanip.mdwn
@@ -270,6 +270,12 @@ Pseudo-code (shadd):
     m <- sm + 1
     RT <- (n[m:XLEN-1] || [0]*m) + (RA)
 
+Pseudo-code (shaddw):
+
+    shift <- sm + 1                # Shift is between 1-4
+    n <- EXTS((RB)[XLEN/2:XLEN-1]) # Only use lower XLEN/2-bits of RB
+    RT <- (n << shift) + (RA)      # Shift n, add RA
+
 Pseudo-code (shadduw):
 
     n <- ([0]*(XLEN/2)) || (RB)[XLEN/2:XLEN-1]
@@ -282,6 +288,12 @@ uint_xlen_t shadd(uint_xlen_t RA, uint_xlen_t RB, uint8_t sm) {
     return (RB << (sm+1)) + RA;
 }
 
+uint_xlen_t shaddw(uint_xlen_t RA, uint_xlen_t RB, uint8_t sm) {
+    uint_xlen_t n = (int_xlen_t)(RB << XLEN / 2) >> XLEN / 2;
+    sm = sm & 0x3;
+    return (n << (sm+1)) + RA;
+}
+
 uint_xlen_t shadduw(uint_xlen_t RA, uint_xlen_t RB, uint8_t sm) {
     uint_xlen_t n = RB & 0xFFFFFFFF;
     sm = sm & 0x3;
diff --git a/openpower/sv/draft_opcode_tables.mdwn b/openpower/sv/draft_opcode_tables.mdwn
index a1cdbd677..527962620 100644
--- a/openpower/sv/draft_opcode_tables.mdwn
+++ b/openpower/sv/draft_opcode_tables.mdwn
@@ -100,7 +100,7 @@ the [[sv/av_opcodes]])
 | NN |    |     |     |    |   00  | 0101 110 |0 | crfbinlog | {TODO}  |
 | NN |    |     |     |    |   00  | 0101 110 |1 | rsvd      |         |
 | NN |    |     |     |    |   10  | 0101 110 |Rc| rsvd      |         |
-| NN |    |     |     |    |   -1  | 0101 110 |Rc| rsvd      |         |
+| NN | RT | RA  | RB  | sm0| sm1 1 | 0101 110 |Rc| shaddw    | X-Form  |
 | NN | RT | RA  | RB  | 0  | itype | 1001 110 |Rc| av minmax | X-Form  |
 | NN | RT | RA  | RB  | 1  |   00  | 1001 110 |Rc| av abss   | X-Form  |
 | NN | RT | RA  | RB  | 1  |   01  | 1001 110 |Rc| av absu   | X-Form  |