From: lkcl <lkcl@web>
Date: Sat, 20 Aug 2022 11:34:30 +0000 (+0100)
Subject: (no commit message)
X-Git-Tag: opf_rfc_ls005_v1~826
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=3b5e7fc54cdf92e510f8e793662c35bbef04f2b4;p=libreriscv.git

---

diff --git a/openpower/sv/ldst.mdwn b/openpower/sv/ldst.mdwn
index b5aa548e8..02e6358a9 100644
--- a/openpower/sv/ldst.mdwn
+++ b/openpower/sv/ldst.mdwn
@@ -444,8 +444,7 @@ and other modes have all been removed, for clarity and simplicity:
     # LD not VLD! (ldbrx if brev=True)
     # this covers unit stride mode and a type of vector offset
     function op_ld(RT, RA, brev, op_width, imm_offs, svctx)
-      for (int i = 0, int j = 0; i < svctx.VL && j < svctx.VL;):
-
+      for (int i = 0, int j = 0; i < svctx.VL && j < svctx.VL):
         if not svctx.unit/el-strided:
             # strange vector mode, compute 64 bit address which is
             # not polymorphic! elwidth hardcoded to 64 here
@@ -460,7 +459,7 @@ and other modes have all been removed, for clarity and simplicity:
         bytereverse = brev XNOR MSR.LE
 
         # read the underlying memory
-        memread <= mem[srcbase + imm_offs];
+        memread <= MEM(srcbase + imm_offs, op_width)
 
         # optionally performs byteswap at op width
         if (bytereverse):
@@ -484,6 +483,28 @@ and other modes have all been removed, for clarity and simplicity:
         i++;
         j++;
 
+For LD/Indexed, the key here is that in the calculation of the Effective Address,
+RA has no elwidth override but RB does.
+
+    # LD not VLD!
+    function op_ld(RT, RA, RB, op_width, svctx)
+      for (int i = 0, int j = 0; i < svctx.VL && j < svctx.VL):
+        if not svctx.el-strided:
+            # RA not polymorphic! elwidth hardcoded to 64 here
+            srcbase = get_polymorphed_reg(RA, 64, i)
+        else:
+            # element stride mode, again RA not polymorphic
+            srcbase = get_polymorphed_reg(RA, 64, 0)
+        # RB *is* polymorphic
+        offs = get_polymorphed_reg(RB, svctx.src_elwidth, i)
+        # sign-extend
+        if svctx.SEA: offs = sext(offs, svctx.src_elwidth, 64)
+        # read the underlying memory
+        memread <= MEM(srcbase + offs, op_width)
+        # proceed to check saturation 
+        ...
+        ...
+
 # Remapped LD/ST
 
 In the [[sv/remap]] page the concept of "Remapping" is described.