Add aperture macro parsing and evaluation.

Aperture macros can get complex with arithmetical operations,
variables and variables substitution.

Current pcb-tools code just read each macro block as an independent
unit, this cannot deal with variables that get changed after used.

This patch splits the task in two: first we parse all macro content
and creates a bytecode representation of all operations. This bytecode
representation will be executed when an AD command is issues passing
the required parameters.

Parsing is heavily based on gerbv using a Shunting Yard approach to
math parsing.

Integration with rs274x.py code is not finished as I need to figure out
how to integrate the final macro primitives with the graphical primitives
already in use.

1 files changed, 106 insertions, 0 deletions

diff --git a/gerber/am_eval.py b/gerber/am_eval.py
new file mode 100644
index 0000000..29b380d
--- /dev/null
+++ b/gerber/am_eval.py
@@ -0,0 +1,106 @@
+#! /usr/bin/env python
+# -*- coding: utf-8 -*-
+
+# copyright 2014 Hamilton Kibbe <ham@hamiltonkib.be>
+# copyright 2014 Paulo Henrique Silva <ph.silva@gmail.com>
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+
+#     http://www.apache.org/licenses/LICENSE-2.0
+
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+""" This module provides RS-274-X AM macro evaluation.
+"""
+
+class OpCode:
+    PUSH  = 1
+    LOAD  = 2
+    STORE = 3
+    ADD   = 4
+    SUB   = 5
+    MUL   = 6
+    DIV   = 7
+    PRIM  = 8
+
+    @staticmethod
+    def str(opcode):
+        if opcode == OpCode.PUSH:
+            return "OPCODE_PUSH"
+        elif opcode == OpCode.LOAD:
+            return "OPCODE_LOAD"
+        elif opcode == OpCode.STORE:
+            return "OPCODE_STORE"
+        elif opcode == OpCode.ADD:
+            return "OPCODE_ADD"
+        elif opcode == OpCode.SUB:
+            return "OPCODE_SUB"
+        elif opcode == OpCode.MUL:
+            return "OPCODE_MUL"
+        elif opcode == OpCode.DIV:
+            return "OPCODE_DIV"
+        elif opcode == OpCode.PRIM:
+            return "OPCODE_PRIM"
+        else:
+            return "UNKNOWN"
+
+def eval_macro(instructions, parameters={}):
+
+    if not isinstance(parameters, type({})):
+        p = {}
+        for i, val in enumerate(parameters):
+            p[i+1] = val
+
+        parameters = p
+
+    stack = []
+    def pop():
+        return stack.pop()
+
+    def push(op):
+        stack.append(op)
+
+    def top():
+        return stack[-1]
+
+    def empty():
+        return len(stack) == 0
+
+    for opcode, argument in instructions:
+        if opcode == OpCode.PUSH:
+            push(argument)
+
+        elif opcode == OpCode.LOAD:
+            push(parameters.get(argument, 0))
+
+        elif opcode == OpCode.STORE:
+            parameters[argument] = pop()
+
+        elif opcode == OpCode.ADD:
+            op1 = pop()
+            op2 = pop()
+            push(op2 + op1)
+
+        elif opcode == OpCode.SUB:
+            op1 = pop()
+            op2 = pop()
+            push(op2 - op2)
+
+        elif opcode == OpCode.MUL:
+            op1 = pop()
+            op2 = pop()
+            push(op2 * op1)
+
+        elif opcode == OpCode.DIV:
+            op1 = pop()
+            op2 = pop()
+            push(op2 / op1)
+
+        elif opcode == OpCode.PRIM:
+            yield "%d,%s" % (argument, ",".join([str(x) for x in stack]))
+            stack = []