From 266ab1d0364bac21c6b17fcc6d063e72fd7ef861 Mon Sep 17 00:00:00 2001
From: Nico Schottelius <nico@nico-notebook.schottelius.org>
Date: Sun, 21 Jul 2019 10:48:35 +0200
Subject: [PATCH] Try fixing shift errors (precendence!)

---
 doc/plan.org                    | 15 +++++++++++++++
 p4src/actions_delta_checksum.p4 | 10 +++++-----
 2 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/doc/plan.org b/doc/plan.org
index 100ebd9..aadbbb8 100644
--- a/doc/plan.org
+++ b/doc/plan.org
@@ -5673,6 +5673,21 @@ TCP6:[2001:db8:1::a00:1]:2343"; sleep 2; done
 Result: no reply, but translated packets seen on h3; wrong IPv4
 checksum; tcp checksum is ok
 -> doing manual calculation to see where diff comes from
+*** TODO Shifting / compile errors
+#+BEGIN_CENTER
+p4c --target bmv2 --arch v1model --std p4-16 "../p4src/checksum_diff.p4" -o "/home/p4/master-thesis/p4src"
+../p4src/actions_delta_checksum.p4(135): warning: <<: Shifting 16-bit value with 17
+    shift_tmp = ((bit<16>) hdr.ipv4.version) << 12 +
+                ^
+../p4src/actions_delta_checksum.p4(135): warning: 524288: value does not fit in 16 bits
+    shift_tmp = ((bit<16>) hdr.ipv4.version) << 12 +
+                ^
+../p4src/actions_delta_checksum.p4(158): error: <<: shift amount limited to 8 bits on this target
+    shift_tmp = ((bit<16>) hdr.ipv4.ttl) << 8 +
+                ^
+Compilation Error
+
+#+END_CENTER
 ** The NetPFGA saga
 Problems encountered:
 - The logfile for a compile run is 10k+ lines
diff --git a/p4src/actions_delta_checksum.p4 b/p4src/actions_delta_checksum.p4
index 8997ba2..37d8bf9 100644
--- a/p4src/actions_delta_checksum.p4
+++ b/p4src/actions_delta_checksum.p4
@@ -132,9 +132,9 @@ action delta_ipv4_from_v6_to_v4()
 
     Does NOT contain payload! -> can be done manually */
 
-    shift_tmp = ((bit<16>) hdr.ipv4.version)   << 12 +
-                ((bit<16>) hdr.ipv4.ihl)       << 8  +
-                ((bit<16>) hdr.ipv4.diff_serv) << 2  +
+    shift_tmp = (bit<16>) (hdr.ipv4.version   << 12) +
+                (bit<16>) (hdr.ipv4.ihl       << 8)  +
+                (bit<16>) (hdr.ipv4.diff_serv << 2)  +
                 ((bit<16>) hdr.ipv4.ecn);
     tmp = tmp + shift_tmp;
 
@@ -148,14 +148,14 @@ action delta_ipv4_from_v6_to_v4()
 
     tmp = tmp + (bit<16>) hdr.ipv4.identification;   /* 16 bit */
 
-    shift_tmp = ((bit<16>) hdr.ipv4.flags) << 13 +
+    shift_tmp = ((bit<16>) (hdr.ipv4.flags) << 13) +
                 ((bit<16>) hdr.ipv4.fragOffset);
     tmp = tmp + shift_tmp;
 
     // tmp = tmp + (bit<16>) hdr.ipv4.flags;            /* 3 bit */
     // tmp = tmp + (bit<16>) hdr.ipv4.fragOffset;       /* 13 bit */
 
-    shift_tmp = ((bit<16>) hdr.ipv4.ttl) << 8 +
+    shift_tmp = ((bit<16>) (hdr.ipv4.ttl) << 8) +
                 ((bit<16>) hdr.ipv4.protocol);
     tmp = tmp + shift_tmp;