hdlc: add call-back function for completely decoded HDLC frames
... and some more comments/documentation
diff --git a/src/hdlc.c b/src/hdlc.c
index 19ba900..d97e6b4 100644
--- a/src/hdlc.c
+++ b/src/hdlc.c
@@ -35,10 +35,13 @@
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 @@
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 @@
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)
diff --git a/src/hdlc.h b/src/hdlc.h
index 2d44e75..2760213 100644
--- a/src/hdlc.h
+++ b/src/hdlc.h
@@ -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);