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osmo-e1-recorder
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hdlc: add call-back function for completely decoded HDLC frames 

... and some more comments/documentation
This commit is contained in:
Harald Welte 2016-11-14 22:06:46 +01:00
parent 1df5cf4950
commit 90bd7b6709
2 changed files with 32 additions and 5 deletions
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19
src/hdlc.c
View File

@ -35,10 +35,13 @@ static int append_bit_out(struct hdlc_proc *hdlc, uint8_t bit)
hdlc->num_bits++;
if (hdlc->num_bits == 8) {
hdlc->num_bits = 0;
pbit_t out;
hdlc->num_bits = 0;
/* generate one output byte */
osmo_ubit2pbit_ext(&out, 0, hdlc->next_outbyte, 0, 8, 0);
/* append to output buffer */
OSMO_ASSERT(hdlc->out.len < sizeof(hdlc->out.buf));
hdlc->out.buf[hdlc->out.len++] = out;
return out;
}
@ -58,6 +61,14 @@ static int process_hdlc_bit(struct hdlc_proc *hdlc, uint8_t bit)
hdlc->num_bits = 0;
DEBUGP("S ");
flag = 1;
if (hdlc->out.len) {
/* call output function if any frame was
* received before the flag octet */
if (hdlc->out_cb)
hdlc->out_cb(hdlc->out.buf, hdlc->out.len,
hdlc->priv);
hdlc->out.len = 0;
}
} else if (!memcmp(five_ones_zero, hdlc->history, sizeof(five_ones_zero))) {
/* 4.3.1 Synchronous transmission: receiver shall
* discard any "0" bit after five contiguous ones */
@ -78,16 +89,16 @@ static int process_hdlc_bit(struct hdlc_proc *hdlc, uint8_t bit)
return out;
}
int process_raw_hdlc(struct hdlc_proc *hdlc, uint8_t *data, unsigned int len)
int process_raw_hdlc(struct hdlc_proc *hdlc, ubit_t *bits, unsigned int len)
{
unsigned int i;
int out;
static int last_out;
DEBUGP("process_raw_hdlc(%s)\n", osmo_hexdump(data,len));
DEBUGP("process_raw_hdlc(%s)\n", osmo_hexdump(bits, len));
for (i = 0; i < len; i ++) {
out = process_hdlc_bit(hdlc, data[i]);
out = process_hdlc_bit(hdlc, bits[i]);
if (out == -123) {
/* suppress repeating Flag characters */
if (last_out != out)

18
src/hdlc.h
View File

@ -2,10 +2,26 @@
#include <osmocom/core/bits.h>
/* structure representing a HDLC decoder process */
struct hdlc_proc {
/* 8 bits history of most recently received bits */
ubit_t history[8];
/* 8 bit buffer for assembling the next output byte */
ubit_t next_outbyte[8];
/* number of bits currently in use in next_outbyte */
uint8_t num_bits;
/* output buffer for re-aligned frame bytes */
struct {
uint8_t buf[1024];
unsigned int len;
} out;
/* call-back ot be called at end of frame */
void (*out_cb)(const uint8_t *data, unsigned int len, void *priv);
/* private data passed to out_cb */
void *priv;
};
int process_raw_hdlc(struct hdlc_proc *hdlc, uint8_t *data, unsigned int len);
/* input given number of raw bits from the bit stream into HDLC */
int process_raw_hdlc(struct hdlc_proc *hdlc, ubit_t *bits, unsigned int len);