Seth Morabito
807a43ce6f
I was alarmed to discover just how slow `String.format()` is for doing integer to hex conversions. Now that a trace window has been added to Symon, it became especially clear that I needed a more efficient way to handle it. I looked into using `Integer.toHexString()`, but I would have had to wrap it to do zero-padding, so I decided to just bite the bullet and do my own with a lookup table. The implementation in `HexUtil` is just as fast as `Integer.toHexString()`, but also zero-pads appropriately. Combined with Java's `+` String concatenation, it seems perfectly adequate. For yet better performance with the trace window, it would make a lot of sense to special-case stepping so that it just pops the top line off the log, and appends to the bottom, rather than re-stringifying the entire trace log each time. This will be a future enhancement.
37 lines
1.1 KiB
Java
37 lines
1.1 KiB
Java
package com.loomcom.symon;
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import com.loomcom.symon.util.HexUtil;
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import junit.framework.TestCase;
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public class HexUtilTest extends TestCase {
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public void testByteToHex() {
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assertEquals("FE", HexUtil.byteToHex(0xfe));
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assertEquals("00", HexUtil.byteToHex(0));
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assertEquals("0A", HexUtil.byteToHex(10));
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}
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public void testByteToHexIgnoresSign() {
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assertEquals("FF", HexUtil.byteToHex(-1));
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}
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public void testByteToHexMasksLowByte() {
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assertEquals("FE", HexUtil.byteToHex(0xfffe));
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assertEquals("00", HexUtil.byteToHex(0xff00));
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}
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public void testWordToHex() {
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assertEquals("0000", HexUtil.wordToHex(0));
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assertEquals("FFFF", HexUtil.wordToHex(65535));
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assertEquals("FFFE", HexUtil.wordToHex(65534));
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}
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public void testWordToHexIgnoresSign() {
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assertEquals("FFFF", HexUtil.wordToHex(-1));
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}
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public void testWordToHexMasksTwoLowBytes() {
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assertEquals("FFFE", HexUtil.wordToHex(0xfffffe));
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assertEquals("FF00", HexUtil.wordToHex(0xffff00));
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}
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}
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