107 lines
2.3 KiB
Go
107 lines
2.3 KiB
Go
package modbus
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import (
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"testing"
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)
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func TestCRC(t *testing.T) {
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var c crc
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var out []byte
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// initialize the CRC object and make sure we get 0xffff as init value
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c.init()
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if c.crc != 0xffff {
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t.Errorf("expected 0xffff, saw 0x%04x", c.crc)
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}
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out = c.value()
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if len(out) != 2 {
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t.Errorf("value() should have returned 2 bytes, got %v", len(out))
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}
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if out[0] != 0xff || out[1] != 0xff {
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t.Errorf("expected {0xff, 0xff} got {0x%02x, 0x%02x}", out[0], out[1])
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}
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// add a few bytes, check the output
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c.add([]byte{0x01, 0x02, 0x03, 0x04, 0x05})
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if c.crc != 0xbb2a {
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t.Errorf("expected 0xbb2a, saw 0x%04x", c.crc)
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}
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out = c.value()
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if len(out) != 2 {
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t.Errorf("value() should have returned 2 bytes, got %v", len(out))
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}
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if out[0] != 0x2a || out[1] != 0xbb {
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t.Errorf("expected {0x2a, 0xbb} got {0x%02x, 0x%02x}", out[0], out[1])
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}
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// add one extra byte, test the output again
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c.add([]byte{0x06})
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if c.crc != 0xddba {
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t.Errorf("expected 0xddba, saw 0x%04x", c.crc)
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}
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out = c.value()
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if len(out) != 2 {
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t.Errorf("value() should have returned 2 bytes, got %v", len(out))
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}
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if out[0] != 0xba || out[1] != 0xdd {
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t.Errorf("expected {0xba, 0xdd} got {0x%02x, 0x%02x}", out[0], out[1])
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}
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// init the CRC once again: the output bytes should be back to 0xffff
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c.init()
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if c.crc != 0xffff {
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t.Errorf("expected 0xffff, saw 0x%04x", c.crc)
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}
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out = c.value()
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if len(out) != 2 {
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t.Errorf("value() should have returned 2 bytes, got %v", len(out))
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}
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if out[0] != 0xff || out[1] != 0xff {
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t.Errorf("expected {0xff, 0xff} got {0x%02x, 0x%02x}", out[0], out[1])
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}
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return
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}
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func TestCRCIsEqual(t *testing.T) {
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var c crc
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var out []byte
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// initialize the CRC object and feed it a few bytes
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c.init()
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c.add([]byte{0x01, 0x02, 0x03, 0x04, 0x05, 0x06})
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// make sure the register value is what it should be
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if c.crc != 0xddba {
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t.Errorf("expected 0xddba, saw 0x%04x", c.crc)
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}
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// positive test
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if !c.isEqual(0xba, 0xdd) {
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t.Error("isEqual() should have returned true")
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}
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// negative test
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if c.isEqual(0xdd, 0xba) {
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t.Error("isEqual() should have returned false")
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}
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// loopback test
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out = c.value()
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if !c.isEqual(out[0], out[1]) {
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t.Error("isEqual() should have returned true")
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}
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// an empty payload should have a CRC of 0xffff
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c.init()
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if !c.isEqual(0xff, 0xff) {
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t.Error("isEqual() should have returned true")
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}
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return
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}
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