From: Luke Kenneth Casson Leighton <lkcl@lkcl.net>
Date: Tue, 1 Dec 2020 15:26:15 +0000 (+0000)
Subject: update setvl(i) pseudocode and format
X-Git-Tag: convert-csv-opcode-to-binary~1554
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=7ba7a1cb99030fcda571bc9e3ce562d91ef192ac;p=libreriscv.git

update setvl(i) pseudocode and format
---

diff --git a/openpower/sv/setvl.mdwn b/openpower/sv/setvl.mdwn
index fbd75fcc9..98e5991b8 100644
--- a/openpower/sv/setvl.mdwn
+++ b/openpower/sv/setvl.mdwn
@@ -8,29 +8,42 @@ See links:
 
 # Format
 
-| 0..5 |6....10|11....16|17...20|21.22|23.24|25.26|27...30|31|  name   |
-|------|-------|--------|-------|-----|-----|--|--|-------|--|---------|
-| 19   | RT    | RA     |       | XO[0:4]        XO[5:10] |/ | XL-Form |
-| 19   | (RT|0)| (RA|0) |vlimmed      |//   |vs|ms| NNNNN |/ | setvl/i |
+| 0..5 |6....10|11....15|16.20|21.22.23.24..25|26......30|31|  name   |
+|------|-------|--------|-----|---------------|----------|--|---------|
+| 19   | RT    | RA     |     | XO[0:4]       | XO[5:10] |Rc| XL-Form |
+| 19   | (RT|0)| (RA|0) |imm  | imm //  vs ms | NNNNNN   |Rc| setvl/i |
 
 # Pseudocode
 
     // instruction fields:
-    rd = get_rt_field();
-    ra = get_ra_field();
-    vlimmed = get_immed_field();
-
+    rd = get_rt_field();         // bits 6..10
+    ra = get_ra_field();         // bits 11..15
+    vlimmed = get_immed_field(); // bits 16..22
+    vs = get_vs_field();         // bit 24
+    ms = get_ms_field();         // bit 25
+    Rc = get_Rc_field();         // bit 31
+
+    // set VL (or not).
+    // 3 options: from SPR, from immed, from ra
     if vs {
-       VL = vlimmed
-    } else {
-       VL = SPR[SV_VL]
+       if ra == 0 {
+           VL = SPR[SV_VL]
+       } else {
+           VL = vlimmed
+       }
+    } elif ra != 0 {
+       VL = GPR[ra]
     }
+
+    // set MVL (or not).
+    // 2 options: from SPR, from immed
     if ms {
        MVL = vlimmed
     } else {
        MVL = SPR[SV_MVL]
     }
-    // calculate VL
+
+    // calculate (limit) VL
     VL = min(VL, MVL)
 
     // store VL, MVL
@@ -38,7 +51,10 @@ See links:
     SPR[SV_MVL] = MVL
 
     // write rd
-    if rd != 0 {
-        // rd is not x0
-        regs[rd] = VL;
+    if rt != 0 {
+        // rt is not zero
+        regs[rt] = VL;
+        if Rc {
+            // update CR from VL
+        }
     }