From: Luke Kenneth Casson Leighton <lkcl@lkcl.net>
Date: Mon, 27 Mar 2023 11:07:08 +0000 (+0100)
Subject: add svshape2 pseudo-code
X-Git-Tag: opf_rfc_ls001_v3~29
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=00e6c538c508a52da5d4b4b0fc9cc6e81599192d;p=libreriscv.git

add svshape2 pseudo-code
---

diff --git a/openpower/sv/rfc/ls009.mdwn b/openpower/sv/rfc/ls009.mdwn
index 1c5625f2b..b3bea0d17 100644
--- a/openpower/sv/rfc/ls009.mdwn
+++ b/openpower/sv/rfc/ls009.mdwn
@@ -1251,7 +1251,80 @@ the SVSTATE SPRs manually.
 \newpage{}
 
 
-# svshape2 (offset) <a name="svshape2"> </a>
+# svshape2 (offset-priority) <a name="svshape2"> </a>
+
+SVM2-Form
+
+| 0-5|6-9 |10|11-15  |16-20  | 21-24  | 25 | 26-31 |  Form      |
+| -- |----|--| ---   | ----- | ------ | -- | ------| --------   |
+| PO |offs|yx| rmm   | SVd   | 100/mm | sk | XO    | SVM2-Form  |
+
+* svshape2 offs,yx,rmm,SVd,sk,mm
+
+Pseudo-code:
+
+```
+    # based on nearest MAXVL compute other dimension
+    MVL <- SVSTATE[0:6]
+    d <- [0] * 6
+    dim <- SVd+1
+    do while d*dim <u ([0]*4 || MVL)
+       d <- d + 1
+    # set up template, then copy once location identified
+    shape <- [0]*32
+    shape[30:31] <- 0b00            # mode
+    shape[0:5] <- (0b0 || SVd)      # x/ydim
+    if SVyx = 0 then
+        shape[18:20] <- 0b000       # ordering xd/yd(/zd)
+        if sk = 0 then shape[6:11] <- 0 # ydim
+        else           shape[6:11] <- 0b111111 # ydim max
+    else
+        shape[18:20] <- 0b010       # ordering yd/xd(/zd)
+        if sk = 1 then shape[6:11] <- 0 # ydim
+        else           shape[6:11] <- d-1 # ydim max
+    # offset (the prime purpose of this instruction)
+    shape[24:27] <- SVo         # offset
+    if sk = 1 then shape[28:29] <- 0b01 # skip 1st dimension
+    else           shape[28:29] <- 0b00 # no skipping
+    # select the mode for updating SVSHAPEs
+    SVSTATE[62] <- mm # set or clear persistence
+    if mm = 0 then
+        # clear out all SVSHAPEs first
+        SVSHAPE0[0:31] <- [0] * 32
+        SVSHAPE1[0:31] <- [0] * 32
+        SVSHAPE2[0:31] <- [0] * 32
+        SVSHAPE3[0:31] <- [0] * 32
+        SVSTATE[32:41] <- [0] * 10 # clear REMAP.mi/o
+        SVSTATE[42:46] <- rmm # rmm exactly REMAP.SVme
+        idx <- 0
+        for bit = 0 to 4
+            if rmm[4-bit] then
+                # activate requested shape
+                if idx = 0 then SVSHAPE0 <- shape
+                if idx = 1 then SVSHAPE1 <- shape
+                if idx = 2 then SVSHAPE2 <- shape
+                if idx = 3 then SVSHAPE3 <- shape
+                SVSTATE[bit*2+32:bit*2+33] <- idx
+                # increment shape index, modulo 4
+                if idx = 3 then idx <- 0
+                else            idx <- idx + 1
+    else
+        # refined SVSHAPE/REMAP update mode
+        bit <- rmm[0:2]
+        idx <- rmm[3:4]
+        if idx = 0 then SVSHAPE0 <- shape
+        if idx = 1 then SVSHAPE1 <- shape
+        if idx = 2 then SVSHAPE2 <- shape
+        if idx = 3 then SVSHAPE3 <- shape
+        SVSTATE[bit*2+32:bit*2+33] <- idx
+        SVSTATE[46-bit] <- 1
+```
+
+Special Registers Altered:
+
+```
+    None
+```
 
 `svshape2` is an additional convenience instruction that prioritises
 setting `SVSHAPE.offset`. Its primary purpose is for use when
@@ -1268,11 +1341,7 @@ in the middle of a register, normally there would be no way to do so except
 through LD/ST.  `SVSHAPE.offset` caters for this scenario and `svshape2`is
 makes it easier.
 
-    svshape2 offs,yx,rmm,SVd,sk,mm
-
-| 0.5|6..9|10|11.15  |16..20 | 21..25 | 25 | 26..31|  name    |
-| -- |----|--| ---   | ----- | ------ | -- | ------| -------- |
-|OPCD|offs|yx| rmm   | SVd   | 100/mm | sk | XO    | svshape  |
+**Operand Fields**:
 
 * **offs** (4 bits) - unsigned offset
 * **yx** (1 bit) - swap XY to YX
@@ -1315,6 +1384,8 @@ discouraged from directly writing to these SPRs.*
 
 # Forms
 
+Add `SVI, SVM, SVM2, SVRM` to `XO (26:31)` Field in Book I, 1.6.2
+
 Add the following to Book I, 1.6.1, SVI-Form
 
 ```
@@ -1343,8 +1414,6 @@ Add the following to Book I, 1.6.1, SVRM-Form
     | PO   | SVme |mi0 | mi1 | mi2 | mo0 | mo1 |pst |///  | XO        |
 ```
 
-* Add `SVI, SVM, SVM2, SVRM` to `XO (26:31)` Field in Book I, 1.6.2
-
 Add the following to Book I, 1.6.2
 
 ```
@@ -1423,5 +1492,8 @@ Add the following to Book I, 1.6.2
 | Form | Book | Page | Version | mnemonic | Description |
 |------|------|------|---------|----------|-------------|
 | SVRM | I    | #    | 3.0B    | svremap    | REMAP enabling instruction |
+| SVM  | I    | #    | 3.0B    | svshape  | REMAP shape instruction |
+| SVM2 | I    | #    | 3.0B    | svshape2 | REMAP shape instruction (2) |
+| SVI  | I    | #    | 3.0B    | svindex | REMAP General-purpose Indexing |
 
 [[!tag opf_rfc]]