[otbn] Adjust BN.LID/BN.SID/BN.MOVR encoding
As these use indirect addressing grd register field is moved to the
field used for grs2 in all other instructions as the given grd value
becomes a base side register to read to generate a bignum side register
index for the destination register.
BN.SID has no destination but the grs2 register field is moved to match
with all other instructions (and so the offset and inc fields match up
with BN.LID/BN.MOVR).
Fixes #3666
Signed-off-by: Greg Chadwick <gac@lowrisc.org>
diff --git a/hw/ip/otbn/data/bignum-insns.yml b/hw/ip/otbn/data/bignum-insns.yml
index 551241b..aba9b47 100644
--- a/hw/ip/otbn/data/bignum-insns.yml
+++ b/hw/ip/otbn/data/bignum-insns.yml
@@ -826,11 +826,11 @@
scheme: bnxid
mapping:
imm: offset
+ rs2: grd
+ rs1: grs1
spp: grs1_inc
dpp: grd_inc
- rs: grs1
funct3: b100
- rd: grd
- mnemonic: bn.sid
synopsis: Store Word (indirect source, indirect destination)
@@ -899,11 +899,11 @@
scheme: bnxid
mapping:
imm: offset
+ rs2: grs2
+ rs1: grs1
spp: grs1_inc
dpp: grs2_inc
- rs: grs1
funct3: b101
- rd: grs2
- mnemonic: bn.mov
synopsis: Copy content between WDRs (direct addressing)
@@ -915,9 +915,6 @@
encoding:
scheme: bnmov
mapping:
- indirect: b0
- spp: bx
- dpp: bx
src: wrs
dst: wrd
@@ -954,13 +951,12 @@
if grd_inc:
GPR[d] = GPR[d] + 1
encoding:
- scheme: bnmov
+ scheme: bnmovr
mapping:
- indirect: b1
+ dst: grd
+ src: grs
spp: grs_inc
dpp: grd_inc
- src: grs
- dst: grd
- mnemonic: bn.wsrrs
synopsis: Atomic Read and Set Bits in WSR
diff --git a/hw/ip/otbn/data/enc-schemes.yml b/hw/ip/otbn/data/enc-schemes.yml
index 6c9955f..34f8ae3 100644
--- a/hw/ip/otbn/data/enc-schemes.yml
+++ b/hw/ip/otbn/data/enc-schemes.yml
@@ -179,6 +179,12 @@
fields:
funct2: 13-12
+# A partial scheme for the bn.mov/bn.movr instructions. Specifies if register
+# indirect lookup is used (bn.mov vs bn.movr)
+indirect:
+ fields:
+ indirect: 31
+
# A specialised encoding for the loop instruction (only one source, no
# destination)
loop:
@@ -309,27 +315,43 @@
- custom0
- funct3
fields:
- imm: 24-22,31-25
- spp: 21
- dpp: 20
- rs: 19-15
- rd: 11-7
+ imm: 11-9,31-25
+ rs2: 24-20
+ rs1: 19-15
+ spp: 8
+ dpp: 7
-# Used by bn.mov and bn.movr
+# Used by bn.mov
bnmov:
parents:
- custom0
- funct3(funct3=b110)
+ - indirect(indirect=b0)
fields:
- indirect: 31
fixed_top:
- bits: 30-22
- value: bxxxxxxxxx
- spp: 21
- dpp: 20
+ bits: 30-20
+ value: bxxxxxxxxxxx
src: 19-15
dst: 11-7
+# Used by bn.movr
+bnmovr:
+ parents:
+ - custom0
+ - funct3(funct3=b110)
+ - indirect(indirect=b1)
+ fields:
+ fixed_top:
+ bits: 30-25
+ value: bxxxxxx
+ dst: 24-20
+ src: 19-15
+ spp: 9
+ dpp: 7
+ unused:
+ bits: 11-10,8
+ value: bxxx
+
# Used by bn.wsrrs and bn.wsrrw
wcsr:
parents:
