From 71e11e17c68bfcb815c76ebda4d20e8a6b89b746 Mon Sep 17 00:00:00 2001
From: Vincent St-Amour <stamourv@dino11.iro.umontreal.ca>
Date: Thu, 24 Jul 2008 18:00:56 -0400
Subject: [PATCH] Push-long now uses a 4-bit opcode. Reduces size a bit. Now we
 have a lot of free opcodes. I'll try to add some "short" versions to the
 label instrs, with only 8 bit of address.

---
 picobit-vm.c | 54 +++++++++++++++++++++++++++---------------------------
 picobit.scm  |  5 ++---
 2 files changed, 29 insertions(+), 30 deletions(-)

diff --git a/picobit-vm.c b/picobit-vm.c
index 4d00a03..2a80701 100644
--- a/picobit-vm.c
+++ b/picobit-vm.c
@@ -1979,24 +1979,25 @@ int read_hex_file (char *filename)
 #define bytecode_hi4 WREG
 #endif
 
-#define PUSH_CONSTANT1 0x00
-#define PUSH_CONSTANT2 0x10
-#define PUSH_STACK1    0x20
-#define PUSH_STACK2    0x30
-#define PUSH_GLOBAL    0x40
-#define SET_GLOBAL     0x50
-#define CALL           0x60
-#define JUMP           0x70
-#define BRANCHES       0x80
-
-#define CALL_TOPLEVEL  0x80
-#define JUMP_TOPLEVEL  0x90
-#define GOTO           0xa0
-#define GOTO_IF_FALSE  0xb0
-#define CLOSURE        0xc0
-#define PRIM1          0xd0
-#define PRIM2          0xe0
-#define PRIM3          0xf0
+#define PUSH_CONSTANT1     0x00
+#define PUSH_CONSTANT2     0x10
+#define PUSH_STACK1        0x20
+#define PUSH_STACK2        0x30
+#define PUSH_GLOBAL        0x40
+#define SET_GLOBAL         0x50
+#define CALL               0x60
+#define JUMP               0x70
+#define LABEL_INSTR        0x80
+#define PUSH_CONSTANT_LONG 0x90
+
+// TODO these are free
+#define GOTO               0xa0
+#define GOTO_IF_FALSE      0xb0
+#define CLOSURE            0xc0
+
+#define PRIM1              0xd0
+#define PRIM2              0xe0
+#define PRIM3              0xf0
 
 #ifdef WORKSTATION
 
@@ -2282,7 +2283,7 @@ void interpreter (void)
   DISPATCH();
 
   /***************************************************************************/
-  CASE(BRANCHES);
+  CASE(LABEL_INSTR);
 
   switch (bytecode_lo4)
     {
@@ -2415,8 +2416,13 @@ void interpreter (void)
   DISPATCH();
 
   /***************************************************************************/
-  CASE(JUMP_TOPLEVEL); // BREGG move, have push long here
+  CASE(PUSH_CONSTANT_LONG);
 
+  /* push-constant [long] */
+  FETCH_NEXT_BYTECODE();
+  arg1 = (bytecode_lo4 << 8) | bytecode;
+  PUSH_ARG1();
+  
   DISPATCH();
 
   /***************************************************************************/
@@ -2610,13 +2616,7 @@ void interpreter (void)
       /* prim #%u8vector-length */
       arg1 = POP(); prim_u8vector_length (); PUSH_ARG1(); break;
     case 12:
-      /* push-constant [long] */ // BREGG move to a 4-bit opcode
-      FETCH_NEXT_BYTECODE(); // TODO BREGG this is a test, the compiler only knows what's in rom or lower, so we only need a byte, unless we change the number of rom addresses OOPS, 8 bits is not enough even for fixnums, we'd probably be ok with 12, though (actually 9, but that's harder to have and 12 gives us more room should we increase the number of rom addresses)
-      arg2 = bytecode;
-      FETCH_NEXT_BYTECODE();
-      arg1 = (arg2 << 8) | bytecode;
-      PUSH_ARG1();
-      arg2 = OBJ_FALSE;
+      // FREE find something to do with this
       break;
     case 13:
       /* shift */
diff --git a/picobit.scm b/picobit.scm
index 4ff9b12..0014e8e 100644
--- a/picobit.scm
+++ b/picobit.scm
@@ -2662,9 +2662,8 @@
               (if (<= n 31)
                   (asm-8 (+ #x00 n))
                   (begin
-                    (asm-8 #xfc)
-                    (asm-8 (quotient n 256)) ;; BREGG this is a test, the compiler cannot know about anything over 256 (as long as no rom goes higher, which might change, watch out for this), so no need for 13 bits OOPS, actually, 8 is not enough for fixnums and rom, revert to 12 and use some of the free instrs ?
-		    (asm-8 (modulo n 256))))) ;; TODO with 13-bit objects, we need 2 bytes, maybe limit to 12, so we could use a byte and a half, but we'd need to use an opcode with only 4 bits, maybe the call/jump stuff can be combined ? FOOBAR
+                    (asm-8 (+ #x90 (quotient n 256)))
+		    (asm-8 (modulo n 256)))))
 
             (define (push-stack n)
               (if (> n 31)
-- 
2.11.4.GIT