dave/smpp-tester
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Implement basic decoding

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This commit is contained in:
PhatPhuckDave
2024-07-30 22:10:57 +02:00
parent 74928d9f7a
commit 76d7102e72
1 changed files with 24 additions and 8 deletions
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32
encoding/gsm7.go
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@@ -65,29 +65,41 @@ func (c *GSM7Coder) Encode(s string, buf *bytes.Buffer) error {
func (c *GSM7Coder) Decode(buf *bytes.Buffer) (string, error) { func (c *GSM7Coder) Decode(buf *bytes.Buffer) (string, error) {
gsm7 := buf.Bytes() gsm7 := buf.Bytes()
var ( var (
output []byte = make([]byte, len(gsm7)*8/7)
offset int = (len(gsm7) / 8) + 1 offset int = (len(gsm7) / 8) + 1
bitshift byte = 0 bitshift byte = 0
leap, shift bool leap, shift bool
) )
log.Println(len(output)) outLength := len(gsm7)*8/7
lengthDiff := outLength - len(gsm7)
gsm7 = append(gsm7, make([]byte, lengthDiff)...)
// We don't care about the last byte
// Unless it's the %8.......
// We'll deal with that later
for index := len(gsm7) - 2; index >= 0; index-- { for index := len(gsm7) - 2; index >= 0; index-- {
octet := gsm7[index] octet := gsm7[index]
bitshift = byte((index + 1) % 8) bitshift = byte((index + 1) % 8)
if bitshift == 7 { if bitshift == 7 {
leap = true leap = true
} }
log.Printf("Index:%-3d Offset:%-3d Bitshift:%-3d CurrentByte:%08b (%-3d) Output(%-3d):%08b (%-3d) Leap:%5v", index, offset, bitshift, gsm7[index], gsm7[index], index+offset, output[index+offset], output[index+offset], leap) log.Printf("Index:%-3d Offset:%-3d Bitshift:%-3d CurrentByte:%08b (%-3d) OffsetByte(%-3d):%08b (%-3d) Leap:%5v", index, offset, bitshift, gsm7[index], gsm7[index], index+offset, gsm7[index+offset], gsm7[index+offset], leap)
mask := byte(255 << (8 - bitshift)) mask := byte(255 << (8 - bitshift))
masked := (mask & octet) >> (8 - bitshift) masked := (mask & octet) >> (8 - bitshift)
log.Printf("Index:%-3d Offset:%-3d Bitshift:%-3d Mask:%08b Masked:%08b", index, offset, bitshift, mask, masked) log.Printf("Index:%-3d Offset:%-3d Bitshift:%-3d Mask:%08b Masked:%08b", index, offset, bitshift, mask, masked)
output[index+offset] |= masked if leap {
InsertAt(&gsm7, index+offset, masked)
continue } else {
gsm7[index+offset] |= masked gsm7[index+offset] |= masked
}
// Remove last bitshift bits
gsm7[index] <<= bitshift gsm7[index] <<= bitshift
// Move the remaining bit once to the right to form septet instead of octet
gsm7[index] >>= 1
log.Printf("Index:%-3d Offset:%-3d Bitshift:%-3d CurrentByte:%08b (%-3d) OffsetByte(%-3d):%08b (%-3d) Leap:%5v", index, offset, bitshift, gsm7[index], gsm7[index], index+offset, gsm7[index+offset], gsm7[index+offset], leap)
leap = false
continue
if !leap { if !leap {
buf.WriteByte(gsm7[index+offset]) buf.WriteByte(gsm7[index+offset])
@@ -113,7 +125,11 @@ func (c *GSM7Coder) Decode(buf *bytes.Buffer) (string, error) {
offset = 1 offset = 1
} }
} }
return "", nil log.Printf("Result: %+v", gsm7)
for _, v := range gsm7 {
log.Printf("%08b", v)
}
return string(gsm7), nil
} }
// Allocation free // Allocation free