74 lines
1.9 KiB
HTML
74 lines
1.9 KiB
HTML
<!DOCTYPE html>
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<!--
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Copyright 2021 Bradley D. Nelson
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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-->
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<head>
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<meta charset="UTF-8">
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<title>Classic EForth</title>
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<link rel="stylesheet" href="static/eforth.css">
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</head>
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<body>
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<h1>Classic EForth</h1>
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{{MENU}}
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<div class="wrapper">
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<p>
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EForth is a delightfully minimalist approach to Forth originated by Bill Muench and Dr. C. H. Ting.
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</p>
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<h2>Classic ESP32forth</h2>
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<p>
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ESP32forth - Version 6.3 for NodeMCU ESP32S - Tweaked for the Web
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</p>
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<p>
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<a href="https://eforth.storage.googleapis.com/releases/ESP32forth-6.3.0.ino">ESP32forth-6.3.0.ino</a>
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- This has Dr. Ting's v6.3 version with WebUI added in to it.
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</p>
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<h3>Classic EForth Quirks</h3>
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<p>
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EForth exclusively uses <code>FOR..NEXT</code> in favor of <code>DO..LOOP</code>.
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<a href="https://github.com/TG9541/stm8ef/wiki/eForth-FOR-..-NEXT">Details</a>
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</p>
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<p>
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This construct has the odd property that it iterates one "extra" time for zero.
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</p>
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<pre>
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: FOO 10 FOR R@ . NEXT ; FOO
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10 9 8 7 6 5 4 3 2 1 0 ok
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</pre>
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<p>
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To permit a more ordinary loop the <code>AFT</code> word is used in the sequence
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<code>FOR..AFT..THEN..NEXT</code>.
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</p>
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<pre>
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: FOO 10 FOR ( 1st time only ) AFT R@ . THEN NEXT ; FOO
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9 8 7 6 5 4 3 2 1 0 ok
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</pre>
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<p>
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The even more enigmatic <code>FOR..WHILE..NEXT..ELSE..THEN</code>
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is used in place of <code>DO..LEAVE..LOOP</code>.
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It allows a while condition to early out of a counted loop.
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</p>
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