Clean up address handling and change autoinc to preincrement

2 files changed, 6 insertions, 4 deletions

diff --git a/isa/checker.cpp b/isa/checker.cpp
index 7bca5c9..770d9d6 100644
--- a/isa/checker.cpp
+++ b/isa/checker.cpp
@@ -17,8 +17,10 @@ void checker::execute() {
 
     if (inst.need_indirect_load) {
         auto addr = mem.fetch(inst.init_address.value());
-        if (inst.need_autoinc_store)
-            mem.store(*inst.init_address, (addr + 1) & 07777);
+        if (inst.need_autoinc_store) {
+            addr = (addr + 1) & 07777;
+            mem.store(*inst.init_address, addr);
+        }
         inst.final_address = addr;
     } else {
         assert(!inst.need_autoinc_store);
diff --git a/isa/decode.cpp b/isa/decode.cpp
index cb6a694..03e2225 100644
--- a/isa/decode.cpp
+++ b/isa/decode.cpp
@@ -252,7 +252,7 @@ instruction_context decode(unsigned int dfifb, unsigned int pc, unsigned int bit
 
     // Instructions with memory operands may be direct or indirect
     if (inst.need_exec_load || inst.need_exec_store || inst.possibly_redirects) {
-        auto addr = (df << 12) | ((bits & 00200) ? (inst.next_pc & 07600) : 0) | (bits & 00177);
+        auto addr = (df << 12) | ((bits & 00200) ? (pc & 07600) : 0) | (bits & 00177);
         if (bits & 00400) {
             inst.need_indirect_load = true;
             inst.init_address = addr;
@@ -262,7 +262,7 @@ instruction_context decode(unsigned int dfifb, unsigned int pc, unsigned int bit
     }
 
     // Non-jump indirect memory operands may be autoincrementing depending on operand bits
-    if (!inst.possibly_redirects && inst.need_indirect_load && ((bits & 00170) == 00010))
+    if (!inst.possibly_redirects && inst.need_indirect_load && ((inst.init_address.value() & 07770) == 00010))
         inst.need_autoinc_store = true;
 
     return inst;