Add fork and join instructions.

vvp/README.txt

@@ -1,7 +1,7 @@
 /*
  * Copyright (c) 2001 Stephen Williams (steve@icarus.com)
  *
- *  $Id: README.txt,v 1.10 2001/03/29 03:46:36 steve Exp $
+ *  $Id: README.txt,v 1.11 2001/03/30 04:55:22 steve Exp $
  */
 
 VVP SIMULATION ENGINE
@@ -29,7 +29,7 @@ semicolon that terminates a statement. Like so:
 The semicolon is required, whether the comment is there or not.
 
 Statements may span multiple lines, as long as there is no text (other
-then the first character of a label) in the first column of hte
+then the first character of a label) in the first column of the
 continuation line.
 
 HEADER SYNTAX
@@ -54,7 +54,7 @@ Labels and symbols consist of the characters:
 	a-z
 	A-Z
 	0-9
-	.$_
+	.$_<>
 
 Labels and symbols may not start with a digit or a '.', so that they
 are easily distinguished from keywords and numbers. A Label is a
@@ -229,6 +229,25 @@ This statement creates a thread with a starting address at the
 instruction given by <symbol>.
 
 
+THREADS IN GENERAL:
+
+Thread statements create the initial threads of a design. These
+include the ``initial'' and ``always'' statements of the original
+Verilog, and possibly some other synthetic threads for various
+purposes. It is also possible to create transient threads from
+behavioral code. These are needed to support such constructs as
+fork/join, named blocks and task activation.
+
+A transient thread is created with a %fork instruction. When a
+transient thread is created this way, the operand to the %fork gives
+the starting address, and the new thread is said to be a child of the
+forking thread. The children of a thread are pushed onto a stack of
+children.
+
+A transient thread is reaped with a %join instruction. %join waits for
+the top thread in the stack of children to complete, then
+continues. It is an error to %join when there are no children.
+
 TRUTH TABLES
 
 The logic that a functor represents is expressed as a truth table. The
@@ -425,6 +444,17 @@ becomes:
 	a	.var "a", 0, 0;
 
 
+* named events
+
+Events in general are implemented as functors, but named events in
+partinular have no inputs and only the event output. The way to
+generate code for these is like so:
+
+	a  .event "name";
+
+This creates a functor and makes it into a mode-2 functor. Then the
+trigger statement, "-> a", cause a ``%set a, 0;'' statement be
+generated. This is sufficient to trigger the event.
 
 /*
  * Copyright (c) 2001 Stephen Williams (steve@icarus.com)

vvp/codes.h

@@ -19,7 +19,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #if !defined(WINNT)
-#ident "$Id: codes.h,v 1.7 2001/03/26 04:00:39 steve Exp $"
+#ident "$Id: codes.h,v 1.8 2001/03/30 04:55:22 steve Exp $"
 #endif
 
 
@@ -39,10 +39,12 @@ extern bool of_ASSIGN(vthread_t thr, vvp_code_t code);
 extern bool of_CMPU(vthread_t thr, vvp_code_t code);
 extern bool of_DELAY(vthread_t thr, vvp_code_t code);
 extern bool of_END(vthread_t thr, vvp_code_t code);
+extern bool of_FORK(vthread_t thr, vvp_code_t code);
 extern bool of_INV(vthread_t thr, vvp_code_t code);
 extern bool of_JMP(vthread_t thr, vvp_code_t code);
 extern bool of_JMP0(vthread_t thr, vvp_code_t code);
 extern bool of_JMP0XZ(vthread_t thr, vvp_code_t code);
+extern bool of_JOIN(vthread_t thr, vvp_code_t code);
 extern bool of_LOAD(vthread_t thr, vvp_code_t code);
 extern bool of_MOV(vthread_t thr, vvp_code_t code);
 extern bool of_SET(vthread_t thr, vvp_code_t code);
@@ -93,6 +95,9 @@ extern void codespace_dump(FILE*fd);
 
 /*
  * $Log: codes.h,v $
+ * Revision 1.8  2001/03/30 04:55:22  steve
+ *  Add fork and join instructions.
+ *
  * Revision 1.7  2001/03/26 04:00:39  steve
  *  Add the .event statement and the %wait instruction.
  *

vvp/compile.cc

@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #if !defined(WINNT)
-#ident "$Id: compile.cc,v 1.18 2001/03/29 03:46:36 steve Exp $"
+#ident "$Id: compile.cc,v 1.19 2001/03/30 04:55:22 steve Exp $"
 #endif
 
 # include  "compile.h"
@@ -69,10 +69,12 @@ const static struct opcode_table_s opcode_table[] = {
       { "%cmp/u",  of_CMPU,   3,  {OA_BIT1,     OA_BIT2,     OA_NUMBER} },
       { "%delay",  of_DELAY,  1,  {OA_NUMBER,   OA_NONE,     OA_NONE} },
       { "%end",    of_END,    0,  {OA_NONE,     OA_NONE,     OA_NONE} },
+      { "%fork",   of_FORK,   1,  {OA_CODE_PTR, OA_NONE,     OA_NONE} },
       { "%inv",    of_INV,    2,  {OA_BIT1,     OA_BIT2,     OA_NONE} },
       { "%jmp",    of_JMP,    1,  {OA_CODE_PTR, OA_NONE,     OA_NONE} },
       { "%jmp/0",  of_JMP0,   2,  {OA_CODE_PTR, OA_BIT1,     OA_NONE} },
       { "%jmp/0xz",of_JMP0XZ, 2,  {OA_CODE_PTR, OA_BIT1,     OA_NONE} },
+      { "%join",   of_JOIN,   0,  {OA_NONE,     OA_NONE,     OA_NONE} },
       { "%load",   of_LOAD,   2,  {OA_BIT1,     OA_FUNC_PTR, OA_NONE} },
       { "%mov",    of_MOV,    3,  {OA_BIT1,     OA_BIT2,     OA_NUMBER} },
       { "%set",    of_SET,    2,  {OA_FUNC_PTR, OA_BIT1,     OA_NONE} },
@@ -685,6 +687,9 @@ void compile_dump(FILE*fd)
 
 /*
  * $Log: compile.cc,v $
+ * Revision 1.19  2001/03/30 04:55:22  steve
+ *  Add fork and join instructions.
+ *
  * Revision 1.18  2001/03/29 03:46:36  steve
  *  Support named events as mode 2 functors.
  *

vvp/examples/fork.vvp

@@ -0,0 +1,33 @@
+:vpi_module "system";
+
+; Copyright (c) 2001  Stephen Williams (steve@icarus.com)
+;
+;    This source code is free software; you can redistribute it
+;    and/or modify it in source code form under the terms of the GNU
+;    General Public License as published by the Free Software
+;    Foundation; either version 2 of the License, or (at your option)
+;    any later version.
+;
+;    This program is distributed in the hope that it will be useful,
+;    but WITHOUT ANY WARRANTY; without even the implied warranty of
+;    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;    GNU General Public License for more details.
+;
+;    You should have received a copy of the GNU General Public License
+;    along with this program; if not, write to the Free Software
+;    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
+
+; This sample demonstrates the behavior of %fork and %join.
+
+S_main .scope "main";
+
+child	%vpi_call "$display", "I'm a child";
+	%end;
+
+parent	%fork	child;
+	%vpi_call "$display", "I'm a parent";
+	%join;
+	%vpi_call "$display", "reaped";
+	%end;
+
+	.thread parent;

vvp/opcodes.txt

@@ -1,7 +1,7 @@
 /*
  * Copyright (c) 2001 Stephen Williams (steve@icarus.com)
  *
- *  $Id: opcodes.txt,v 1.6 2001/03/26 04:00:39 steve Exp $
+ *  $Id: opcodes.txt,v 1.7 2001/03/30 04:55:22 steve Exp $
  */
 
 
@@ -9,7 +9,9 @@
 EXECUTABLE INSTRUCTION OPCODES
 
 Instruction opcodes all start with a % character and have 0 or more
-operands. In no case are there more then 3 operands.
+operands. In no case are there more then 3 operands. This chapter
+describes the specific behavior of each opcode, in hopefully enough
+detail that its complete effect can be predicted.
 
 
 * %assign <var-label>, <delay>, <bit>
@@ -68,9 +70,29 @@ future to reschedule, and is >= 0. If the %delay is zero, then the
 thread yields the processor for another thread, but will be resumed in
 the current time step.
 
+* %fork <code-label>
+
+This instruction is similar to %jmp, except that it creates a new
+thread to start executing at the specified address. The new thread is
+created and pushed onto the child stack.  It is also marked runnable,
+but is not necessarily started until the current thread yields.
+
+The %fork instruction has no effect other then to push a child thread.
+
+See also %join.
+
+
 * %inv <bit>, <wid>
 
-Perform a bitwise invert of the vector starting at <bit>.
+Perform a bitwise invert of the vector starting at <bit>. The result
+replaces the input. Invert means the following, independently for each
+bit:
+
+	0  --> 1
+	1  --> 0
+	x  --> x
+	z  --> x
+
 
 * %jmp <code-label>
 
@@ -87,6 +109,21 @@ values in the part after the /, the jump is taken. For example:
 
 will jump to T_label if bit 8 is x or z.
 
+* %join
+
+This is the partner to %fork. This instruction causes the thread to
+wait for the top thread in the child stack to terminate, then
+continues. It has no effect in the current thread other then to wait
+until the top child is cleared.
+
+It is an error to execute %join if there are no children in the child
+stack. If a child thread terminates before this instruction is called,
+it remains in the stack as a zombie until the %join reaps it.
+
+If a thread terminates (i.e. executes %end) all its children are
+terminated as well.
+
+
 * %load <bit>, <functor-label>
 
 This instruction loads a value from the given functor output into the

vvp/vthread.cc

@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #if !defined(WINNT)
-#ident "$Id: vthread.cc,v 1.13 2001/03/29 03:46:36 steve Exp $"
+#ident "$Id: vthread.cc,v 1.14 2001/03/30 04:55:22 steve Exp $"
 #endif
 
 # include  "vthread.h"
@@ -34,6 +34,10 @@ struct vthread_s {
       unsigned long pc;
       unsigned char *bits;
       unsigned short nbits;
+	/* This points to the top (youngest) child of the thread. */
+      struct vthread_s*child;
+	/* This is set if the parent is waiting for me to end. */
+      struct vthread_s*reaper;
 	/* This is used for keeping wait queues. */
       struct vthread_s*next;
 };
@@ -78,6 +82,8 @@ vthread_t v_newthread(unsigned long pc)
       thr->pc = pc;
       thr->bits = (unsigned char*)malloc(16);
       thr->nbits = 16*4;
+      thr->child = 0;
+      thr->reaper = 0;
       thr->next = 0;
 
       thr_put_bit(thr, 0, 0);
@@ -87,6 +93,13 @@ vthread_t v_newthread(unsigned long pc)
       return thr;
 }
 
+static void vthread_reap(vthread_t thr)
+{
+      assert(thr->next == 0);
+      assert(thr->child == 0);
+      free(thr);
+}
+
 
 /*
  * This function runs a thread by fetching an instruction,
@@ -169,10 +182,21 @@ bool of_DELAY(vthread_t thr, vvp_code_t cp)
 
 bool of_END(vthread_t thr, vvp_code_t cp)
 {
-	//printf("thread %p: %%end\n", thr);
+      if (thr->reaper)
+	    schedule_vthread(thr->reaper, 0);
+      thr->reaper = thr;
       return false;
 }
 
+bool of_FORK(vthread_t thr, vvp_code_t cp)
+{
+      vthread_t child = v_newthread(cp->cptr);
+      child->child = thr->child;
+      thr->child = child;
+      schedule_vthread(child, 0);
+      return true;
+}
+
 bool of_INV(vthread_t thr, vvp_code_t cp)
 {
       assert(cp->bit_idx1 >= 4);
@@ -214,6 +238,19 @@ bool of_JMP0XZ(vthread_t thr, vvp_code_t cp)
       return true;
 }
 
+bool of_JOIN(vthread_t thr, vvp_code_t cp)
+{
+      assert(thr->child);
+      if (thr->child->reaper == thr->child) {
+	    vthread_reap(thr->child);
+	    return true;
+      }
+
+      assert(thr->child->reaper == 0);
+      thr->child->reaper = thr;
+      return false;
+}
+
 bool of_LOAD(vthread_t thr, vvp_code_t cp)
 {
       assert(cp->bit_idx1 >= 4);
@@ -278,6 +315,9 @@ bool of_WAIT(vthread_t thr, vvp_code_t cp)
 
 /*
  * $Log: vthread.cc,v $
+ * Revision 1.14  2001/03/30 04:55:22  steve
+ *  Add fork and join instructions.
+ *
  * Revision 1.13  2001/03/29 03:46:36  steve
  *  Support named events as mode 2 functors.
  *