Added support for p-registers to allow register access in calling fun…

…ction's stack

src/main/java/myworld/hummingbird/assembler/Assembler.java

@@ -46,7 +46,7 @@ public Assembler(){
         labelUse = Pattern.compile("\\$(\\$)?\\w+");
         symbolName = Pattern.compile("\\D\\w+");
         symbolUse = Pattern.compile("%\\D\\w+");
-        register = Pattern.compile("r\\d+");
+        register = Pattern.compile("[rp]\\d+");
         instruction = Pattern.compile("\\w+");
         intLiteral = Pattern.compile("[IiLl]?(0x|0b|0o)?-?\\d+");
         floatLiteral = Pattern.compile("[FfDd]-?\\d*((\\.)?\\d+)?([eE]-?\\d+)?");
@@ -316,10 +316,16 @@ protected int parseRegister(CharStream asm) throws AssemblyException {
         try{
             var sequence = consume(asm, register);
             if(sequence != null) {
-                var str = sequence.subSequence(1, sequence.length()).toString(); // Drop leading 'r'
-                return Integer.parseInt(str);
+                return switch (sequence.charAt(0)){
+                    // Drop leading 'r' or 'p' and parse reference.
+                    case 'r' -> Integer.parseInt(sequence.subSequence(1, sequence.length()).toString());
+                    case 'p' -> -(Integer.parseInt(sequence.subSequence(1, sequence.length()).toString()) + Fiber.CALL_FRAME_SAVED_REGISTERS + 1);
+                    default -> throw new AssemblyException("Invalid register reference: " + asm.debug(10));
+                };
             }
-        }catch (Exception e){}
+        }catch (Exception e){
+            throw new AssemblyException("Invalid register reference: " + asm.debug(10));
+        }
         throw new AssemblyException("Invalid register reference: " + asm.debug(10));
     }
 

src/main/java/myworld/hummingbird/instructions/OpcodeImpl.java

@@ -21,7 +21,7 @@ static int dispatchCall(Fiber fiber, Opcode ins, int regOffset, int ip, int targ
         }
 
         ip = target;
-        return ip;
+        return -ip;
     }
 
     static int foreignCall(Fiber fiber, Opcode ins, int regOffset, int ip, int symbolIndex){
@@ -33,6 +33,7 @@ static int foreignCall(Fiber fiber, Opcode ins, int regOffset, int ip, int symbo
         ip = ip + 1;
         try {
             func.call(fiber.vm, fiber);
+            fiber.restoreCallContext();
         } catch (Exception e) {
             ip = fiber.vm.trap(e, fiber.registers, ip);
         }

src/test/java/myworld/hummingbird/test/TestPrograms.java

@@ -18,9 +18,11 @@ public class TestPrograms {
     public final HummingbirdVM countOneMillion = load("myworld/hummingbird/test/programs/countOneMillion.hasm");
     public final HummingbirdVM callOneMillion = load("myworld/hummingbird/test/programs/callOneMillion.hasm");
     public final HummingbirdVM fibonacci30 = load("myworld/hummingbird/test/programs/fibonacci30.hasm");
+    public final HummingbirdVM fibonacci30Call0 = load("myworld/hummingbird/test/programs/fibonacci30Call0.hasm");
     public final HummingbirdVM goldenRatio = load("myworld/hummingbird/test/programs/goldenRatio.hasm");
     public final HummingbirdVM simpleFunction = load("myworld/hummingbird/test/programs/simpleFunction.hasm");
     public final HummingbirdVM simpleFiber = load("myworld/hummingbird/test/programs/simpleFiber.hasm");
+    public final HummingbirdVM recursiveAdd = load("myworld/hummingbird/test/programs/recursiveAdd.hasm");
     public final HummingbirdVM recursiveCountOneMillion = load("myworld/hummingbird/test/programs/recursiveCountOneMillion.hasm");
     public final HummingbirdVM mathBench = load("myworld/hummingbird/test/programs/mathBench.hasm");
 
@@ -41,8 +43,10 @@ public Map<String, HummingbirdVM> hvmTestPrograms(){
         programs.put("countOneMillion", countOneMillion);
         programs.put("callOneMillion", callOneMillion);
         programs.put("fibonacci30", fibonacci30);
+        programs.put("fibonacci30Call0", fibonacci30Call0);
         programs.put("simpleFiber", simpleFiber);
         programs.put("simpleFunction", simpleFunction);
+        programs.put("recursiveAdd", recursiveAdd);
         programs.put("recursiveCountOneMillion", recursiveCountOneMillion);
         programs.put("goldenRatio", goldenRatio);
         programs.put("mathBench", mathBench);

src/test/resources/myworld/hummingbird/test/programs/callOneMillion.hasm

@@ -7,11 +7,11 @@
 .code
     CONST r0, 0
     CONST r1, 1000000
+    CONST r2, 1
   loop:
-    CALL0 r4, $callOneMillion
-    ADD r0, r0, r4
+    CALL0 r3, $callOneMillion
+    ADD r0, r0, r3
     IFLT r0, r1, $loop
     RETURN r0
   callOneMillion:
-    CONST r0, 1
-    RETURN r0
+    RETURN p0

src/test/resources/myworld/hummingbird/test/programs/fibonacci30Call0.hasm

@@ -0,0 +1,29 @@
+.symbols
+    fibonacci function $fibonacci
+            long
+            parameters 3
+            registers 7
+
+.code
+  # fib(30)
+  CONST r1, 30
+  CALL0 r2, $fibonacci#, r1, 1
+  RETURN r2
+  fibonacci: # int fibonacci(n)
+    CONST r2, 2
+    IFGE p0, r2, $recurse
+    RETURN p0
+  recurse:
+    #fib(n - 1)
+    CONST r1, 1
+    SUB r3, p0, r1 # r0 = n - 1
+    #COPY r3, r0
+    CALL0 r4, $fibonacci #, r0, 1
+
+    #fib(n - 2)
+    SUB r5, r3, r1 # r0 = n - 2
+    #COPY r5, r0
+    CALL0 r6, $fibonacci #, r0, 1
+
+    ADD r0, r4, r6
+    RETURN r0

src/test/resources/myworld/hummingbird/test/programs/recursiveAdd.hasm

@@ -0,0 +1,14 @@
+.code
+    CONST r0, 1
+    CONST r1, 10
+    CALL0 r2, $add
+    RETURN r2
+  add:
+    IFEQ p0, p1, $done
+    CONST r1, 1
+    ADD r0, p1, r1
+    COPY r1, p0
+    CALL0 r2, $add
+    RETURN r2
+  done:
+    RETURN p1