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[libreriscv.git] / A_Harmonised_RVV_and_Packed_SIMD.mdwn

diff --git a/A_Harmonised_RVV_and_Packed_SIMD.mdwn b/A_Harmonised_RVV_and_Packed_SIMD.mdwn
index 79ee247317836fbd7a9ef99838530b5699c5d2ad..02feff5b21e1be932b080baa557ee7cbf7bca237 100644 (file)
--- a/A_Harmonised_RVV_and_Packed_SIMD.mdwn
+++ b/A_Harmonised_RVV_and_Packed_SIMD.mdwn
@@ -1,4 +1,4 @@
-# Proposal to harmonise RV Vector spec with Packed SIMD ("Harmonised" RVP)
+# Proposal to harmonise RV Vector spec with Andes Packed SIMD ("Harmonised" RVP)
 
 ##### MVL, setvl instruction & VL CSR work as per RV Vector spec.
 
@@ -50,16 +50,16 @@ The above are pure subsets of valid RVV VCFG configurations (and hence forward c
 
 ## 16-bit Arithmetic
 
-| Mnemonic           | 16-bit Instruction        | Harmonised RVP Equivalent |
+| Andes Mnemonic           | 16-bit Instruction        | Harmonised RVP Equivalent |
 | ------------------ | ------------------------- | ------------------- |
-| ADD16 rt, ra, rb   | add                       | VADD (r16 <= rt,ra,rb <= r29), mm=00|
-| RADD16 rt, ra, rb  | Signed Halving add        | VRADD (r16 <= rt,ra,rb <= r23), mm=00|
-| URADD16 rt, ra, rb | Unsigned Halving add      | VRADD (r24 <= rt,ra,rb <= r29), mm=00|
+| ADD16 rt, ra, rb   | Add                       | VADD (r16 <= rt,ra,rb <= r29), mm=00|
+| RADD16 rt, ra, rb  | Signed Halving add        | RADD (r16 <= rt,ra,rb <= r23), mm=00|
+| URADD16 rt, ra, rb | Unsigned Halving add      | RADD (r24 <= rt,ra,rb <= r29), mm=00|
 | KADD16 rt, ra, rb  | Signed Saturating add     | VADD (r16 <= rt,ra,rb <= r23), mm=01|
 | UKADD16 rt, ra, rb | Unsigned Saturating add   | VADD (r24 <= rt,ra,rb <= r29), mm=01|
-| SUB16 rt, ra, rb   | sub                       | VSUB (r16 <= rt,ra,rb <= r29), mm=00|
-| RSUB16 rt, ra, rb  | Signed Halving sub        | VRSUB (r16 <= rt,ra,rb <= r23), mm=00|
-| URSUB16 rt, ra, rb | Unsigned Halving sub                | VRSUB (r24 <= rt,ra,rb <= r29), mm=00|
+| SUB16 rt, ra, rb   | Subtract                  | VSUB (r16 <= rt,ra,rb <= r29), mm=00|
+| RSUB16 rt, ra, rb  | Signed Halving sub        | RSUB (r16 <= rt,ra,rb <= r23), mm=00|
+| URSUB16 rt, ra, rb | Unsigned Halving sub                | RSUB (r24 <= rt,ra,rb <= r29), mm=00|
 | KSUB16 rt, ra, rb  | Signed Saturating sub               | VSUB (r16 <= rt,ra,rb <= r23), mm=01|
 | UKSUB16 rt, ra, rb | Unsigned Saturating sub             | VSUB (r24 <= rt,ra,rb <= r29), mm=01|
 | CRAS16 rt, ra, rb  | Cross Add & Sub                     | |
@@ -75,16 +75,59 @@ The above are pure subsets of valid RVV VCFG configurations (and hence forward c
 
 ## 8-bit Arithmetic
 
-| Mnemonic           | 16-bit Instruction        | Harmonised RVP Equivalent |
+| Andes Mnemonic           | 8-bit Instruction        | Harmonised RVP Equivalent |
 | ------------------ | ------------------------- | ------------------- |
-| ADD8 rt, ra, rb    | add                       | VADD (r2 <= rt,ra,rb <= r15), mm=00 |
-| RADD8 rt, ra, rb   | Signed Halving add        | VRADD (r2 <= rt,ra,rb <= r7), mm=00 |
-| URADD8 rt, ra, rb  | Unsigned Halving add      | VRADD (r8 <= rt,ra,rb <= r15), mm=00 |
+| ADD8 rt, ra, rb    | Add                       | VADD (r2 <= rt,ra,rb <= r15), mm=00 |
+| RADD8 rt, ra, rb   | Signed Halving add        | RADD (r2 <= rt,ra,rb <= r7), mm=00 |
+| URADD8 rt, ra, rb  | Unsigned Halving add      | RADD (r8 <= rt,ra,rb <= r15), mm=00 |
 | KADD8 rt, ra, rb   | Signed Saturating add     | VADD (r2 <= rt,ra,rb <= r7), mm=01 |
 | UKADD8 rt, ra, rb  | Unsigned Saturating add   | VADD (r8 <= rt,ra,rb <= r15), mm=01 |
-| SUB8 rt, ra, rb    | sub                       | VSUB (r2 <= rt,ra,rb <= r15), mm=00 |
-| RSUB8 rt, ra, rb   | Signed Halving sub        | VRSUB (r2 <= rt,ra,rb <= r7), mm=00 |
-| URSUB8 rt, ra, rb  | Unsigned Halving sub      | VRSUB (r8 <= rt,ra,rb <= r15), mm=00 |
+| SUB8 rt, ra, rb    | Subtract                  | VSUB (r2 <= rt,ra,rb <= r15), mm=00 |
+| RSUB8 rt, ra, rb   | Signed Halving sub        | RSUB (r2 <= rt,ra,rb <= r7), mm=00 |
+| URSUB8 rt, ra, rb  | Unsigned Halving sub      | RSUB (r8 <= rt,ra,rb <= r15), mm=00 |
 | KSUB8 rt, ra, rb   | Signed Saturating sub        | VSUB (r2 <= rt,ra,rb <= r7), mm=01 |
 | UKSUB8 rt, ra, rb  | Unsigned Saturating sub      | VSUB (r8 <= rt,ra,rb <= r15), mm=01 |
 
+## 16-bit Shifts
+
+SRA[I]16/SRL[I]16/SLL[I]16 to be mapped to VOP shift instructions in same manner as ADD16/SUB16
+
+The “K” (Saturation) and “u” (Rounding) variants could be encoded using VOP’s mm field (mm=01 is saturated or rounded shift, mm=00 is standard VOP shift)
+
+| Andes Mnemonic             | 16-bit Instruction         | Harmonised RVP Equivalent |
+| ------------------   | -------------------------  | ------------------- |
+| SRA16 rt, ra, rb     | Shift right arithmetic     | VSRA (r16 <= rt,ra,rb <= r29), mm=00|
+| SRAI16 rt, ra, im    | Shift right arithmetic imm | VSRAI (r16 <= rt,ra <= r29), mm=00|
+| SRA16.u rt, ra, rb   | Rounding Shift right arithmetic     | VSRA (r16 <= rt,ra,rb <= r29), mm=01|
+| SRAI16.u rt, ra, im  | Rounding Shift right arithmetic imm | VSRAI (r16 <= rt,ra <= r29), mm=01|
+| SRL16 rt, ra, rb     | Shift right logical        | VSRL (r16 <= rt,ra,rb <= r29), mm=00|
+| SRLI16 rt, ra, im    | Shift right logical imm    | VSRLI (r16 <= rt,ra <= r29), mm=00|
+| SRL16.u rt, ra, rb   | Rounding Shift right logical     | VSRL (r16 <= rt,ra,rb <= r29), mm=01|
+| SRLI16.u rt, ra, im  | Rounding Shift right logical imm | VSLRI (r16 <= rt,ra <= r29), mm=01|
+| SLL16 rt, ra, rb     | Shift left logical         | VSLL (r16 <= rt,ra,rb <= r29), mm=00|
+| SLLI16 rt, ra, im    | Shift left logical imm     | VSLLI (r16 <= rt,ra <= r29), mm=00|
+| KSLL16 rt, ra, rb    | Saturating Shift left logical       | VSLL (r16 <= rt,ra,rb <= r29), mm=01|
+| KSLLI16 rt, ra, im   | Saturating Shift left logical imm   | VSLLI (r16 <= rt,ra <= r29), mm=01|
+| KSLRA16 rt, ra, rb    | Saturating Shift left logical or Shift right arithmetic              ||
+| KSLRA16.u rt, ra, rb  | Saturating Shift left logical or Rounding Shift right arithmetic     ||
+
+
+## 8-bit Shifts
+
+Andes SIMD Packed ISA omits 8 bit shifts, but these can be encoded in Harmonised RVP as follows:
+
+| Andes Mnemonic             | 8-bit Instruction         | Harmonised RVP Equivalent |
+| ------------------   | -------------------------  | ------------------- |
+| n/a     | Shift right arithmetic     | VSRA (r2 <= rt,ra,rb <= r15), mm=00|
+| n/a     | Shift right arithmetic imm | VSRAI (r2 <= rt,ra <= r15), mm=00|
+| n/a     | Rounding Shift right arithmetic     | VSRA (r2 <= rt,ra,rb <= r15), mm=01|
+| n/a     | Rounding Shift right arithmetic imm | VSRAI (r2 <= rt,ra <= r15), mm=01|
+| n/a     | Shift right logical        | VSRL (r2 <= rt,ra,rb <= r15), mm=00|
+| n/a     | Shift right logical imm    | VSRLI (r2 <= rt,ra <= r15), mm=00|
+| n/a     | Rounding Shift right logical     | VSRL (r2 <= rt,ra,rb <= r15), mm=01|
+| n/a     | Rounding Shift right logical imm | VSLRI (r2 <= rt,ra <= r15), mm=01|
+| n/a     | Shift left logical         | VSLL (r2 <= rt,ra,rb <= r15), mm=00|
+| n/a     | Shift left logical imm     | VSLLI (r2 <= rt,ra <= r15), mm=00|
+| n/a     | Saturating Shift left logical       | VSLL (r2 <= rt,ra,rb <= r15), mm=01|
+| n/a     | Saturating Shift left logical imm   | VSLLI (r2 <= rt,ra <= r15), mm=01|
+