87 lines
2.5 KiB
C
87 lines
2.5 KiB
C
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#include "mp1.h"
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#include <string.h>
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//#include <ctype.h>
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static void mp1Decode(MP1 *mp1) {
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MP1Packet packet; // A decoded packet struct
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uint8_t *buffer = mp1->buffer; // Get the buffer from the protocol context
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packet.dataLength = mp1->packetLength;
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packet.data = buffer;
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if (mp1->callback) mp1->callback(&packet);
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}
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void mp1Poll(MP1 *mp1) {
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int byte;
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// Read bytes from the modem until we reach EOF
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while ((byte = kfile_getc(mp1->modem)) != EOF) {
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if (!mp1->escape && byte == HDLC_FLAG) {
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// We are not in an escape sequence and we
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// found a HDLC_FLAG. This can mean two things:
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if (mp1->packetLength >= MP1_MIN_FRAME_LENGTH) {
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// We already have more data than the minimum
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// frame length, which means the flag signifies
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// the end of the packet. Pass control to the
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// decoder.
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mp1Decode(mp1);
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}
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// If the above is not the case, this must be the
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// beginning of a frame
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mp1->reading = true;
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mp1->packetLength = 0;
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// We have indicated that we are reading,
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// and reset the length counter. Now we'll
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// continue to the next byte.
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continue;
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}
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if (!mp1->escape && byte == HDLC_RESET) {
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// Not good, we got a reset. The transmitting
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// party may have encountered an error. We'll
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// stop receiving this packet immediately.
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mp1->reading = false;
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continue;
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}
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if (!mp1->escape && byte == AX25_ESC) {
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// We found an escape character. We'll set
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// the escape seqeunce indicator so we don't
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// interpret the next byte as a reset or flag
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mp1->escape = true;
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continue;
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}
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// Now let's get to the actual reading of the data
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if (mp1->reading) {
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if (mp1->packetLength < MP1_MAX_FRAME_LENGTH) {
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// If the length of the current incoming frame is
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// still less than our max length, put the incoming
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// byte in the buffer.
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mp1->buffer[mp1->packetLength++] = byte;
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} else {
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// If not, we have a problem: The buffer has overrun
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// We need to stop receiving, and the packet will be
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// dropped :(
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mp1->reading = false;
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}
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}
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// We need to set the escape sequence indicator back
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// to false after each byte.
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mp1->escape = false;
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}
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if (kfile_error(mp1->modem)) {
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// If there was an error from the modem, we'll be rude
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// and just reset it. No error handling is done for now.
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kfile_clearerr(mp1->modem);
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}
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}
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void mp1Init(MP1 *mp1, KFile *modem, mp1_callback_t callback) {
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// Allocate memory for our protocol "object"
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memset(mp1, 0, sizeof(*mp1));
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mp1->modem = modem;
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mp1->callback = callback;
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}
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