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Decoding of BCD messages

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This commit is contained in:
Max Lapan
2022-11-25 19:46:02 +01:00
parent 21f375c900
commit e294e03618
1 changed files with 51 additions and 3 deletions
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lib/subghz/protocols/pocsag.c
+51 -3
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@@ -22,6 +22,12 @@ static const SubGhzBlockConst pocsag_const = {
#define POCSAG_FRAME_SYNC_CODE 0x7CD215D8
#define POCSAG_IDLE_CODE_WORD 0x7A89C197
#define POCSAG_FUNC_NUM 0
#define POCSAG_FUNC_ALERT1 1
#define POCSAG_FUNC_ALERT2 2
#define POCSAG_FUNC_ALPHANUM 3
static const char* bcd_chars = "*U -)(";
struct SubGhzProtocolDecoderPocsag {
SubGhzProtocolDecoderBase base;
@@ -94,9 +100,8 @@ static void pocsag_decode_address_word(SubGhzProtocolDecoderPocsag* instance, ui
instance->func = (data >> 11) & 0b11;
}
// decode message word, maintaining instance state for partial decoding. Return true if more data
// might follow or false if end of message reached.
static bool pocsag_decode_message_word(SubGhzProtocolDecoderPocsag* instance, uint32_t data) {
static bool decode_message_alphanumeric(SubGhzProtocolDecoderPocsag* instance, uint32_t data) {
for (uint8_t i = 0; i < 20; i++) {
instance->char_data >>= 1;
if (data & (1 << 30)) {
@@ -116,6 +121,47 @@ static bool pocsag_decode_message_word(SubGhzProtocolDecoderPocsag* instance, ui
}
static void decode_message_numeric(SubGhzProtocolDecoderPocsag* instance, uint32_t data) {
// 5 groups with 4 bits each
uint8_t val;
for (uint8_t i = 0; i < 5; i++) {
val = (data >> (27 - i*4)) & 0b1111;
// reverse the order of 4 bits
val = (val & 0x5) << 1 | (val & 0xA) >> 1;
val = (val & 0x3) << 2 | (val & 0xC) >> 2;
if (val <= 9)
val += '0';
else
val = bcd_chars[val-10];
furi_string_push_back(instance->msg, val);
}
}
// decode message word, maintaining instance state for partial decoding. Return true if more data
// might follow or false if end of message reached.
static bool pocsag_decode_message_word(SubGhzProtocolDecoderPocsag* instance, uint32_t data) {
switch (instance->func) {
case POCSAG_FUNC_ALPHANUM:
return decode_message_alphanumeric(instance, data);
case POCSAG_FUNC_NUM:
decode_message_numeric(instance, data);
return true;
case POCSAG_FUNC_ALERT1:
FURI_LOG_I(TAG, "Alert1");
return true;
case POCSAG_FUNC_ALERT2:
FURI_LOG_I(TAG, "Alert2");
return true;
}
return false;
}
// Function called when current message got decoded, but other messages might follow
static void pocsag_message_done(SubGhzProtocolDecoderPocsag* instance) {
// append the message to the long-term storage string
@@ -186,6 +232,7 @@ void subghz_protocol_decoder_pocsag_feed(void* context, bool level, uint32_t dur
// handle codewords
if (instance->decoder.decode_count_bit == POCSAG_CW_BITS) {
codeword = (uint32_t)(instance->decoder.decode_data & POCSAG_CW_MASK);
FURI_LOG_I(TAG, "cw: %" PRIx32, codeword);
switch (codeword) {
case POCSAG_IDLE_CODE_WORD:
instance->codeword_idx++;
@@ -209,6 +256,7 @@ void subghz_protocol_decoder_pocsag_feed(void* context, bool level, uint32_t dur
case PocsagDecoderStepMessage:
if (instance->decoder.decode_count_bit == POCSAG_CW_BITS) {
codeword = (uint32_t)(instance->decoder.decode_data & POCSAG_CW_MASK);
FURI_LOG_I(TAG, "mw: %" PRIx32, codeword);
switch (codeword) {
case POCSAG_IDLE_CODE_WORD:
// Idle during the message stops the message