diff options
| -rw-r--r-- | src/flip_bits.c | 29 | ||||
| -rw-r--r-- | src/flip_bits.h | 4 | ||||
| -rw-r--r-- | src/hdlc.c | 111 | ||||
| -rw-r--r-- | src/hdlc.h | 18 |
4 files changed, 162 insertions, 0 deletions
diff --git a/src/flip_bits.c b/src/flip_bits.c new file mode 100644 index 0000000..f33994e --- /dev/null +++ b/src/flip_bits.c @@ -0,0 +1,29 @@ +#include <stdint.h> +#include "flip_bits.h" + +static uint8_t flip_table[256]; + +void init_flip_bits(void) +{ + int i,k; + + for (i = 0 ; i < 256 ; i++) { + uint8_t sample = 0 ; + for (k = 0; k<8; k++) { + if ( i & 1 << k ) sample |= 0x80 >> k; + } + flip_table[i] = sample; + } +} + +uint8_t *flip_buf_bits(uint8_t *buf, int len) +{ + int i; + uint8_t *start = buf; + + for (i = 0 ; i < len; i++) { + buf[i] = flip_table[(uint8_t)buf[i]]; + } + + return start; +} diff --git a/src/flip_bits.h b/src/flip_bits.h new file mode 100644 index 0000000..319a181 --- /dev/null +++ b/src/flip_bits.h @@ -0,0 +1,4 @@ +#pragma once + +void init_flip_bits(void); +uint8_t *flip_buf_bits(uint8_t * buf , int len); diff --git a/src/hdlc.c b/src/hdlc.c new file mode 100644 index 0000000..1768dfd --- /dev/null +++ b/src/hdlc.c @@ -0,0 +1,111 @@ +#include <stdint.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> + +#include <sys/types.h> +#include <sys/stat.h> +#include <fcntl.h> + +#include <osmocom/core/utils.h> +#include <osmocom/core/bits.h> + +#include "hdlc.h" + +#if 0 +#define DEBUGP(x, args ...) fprintf(stderr, x, ## args) +#else +#define DEBUGP(x, args ...) do {} while (0) +#endif + +static const ubit_t five_ones[] = { 1,1,1,1,1 }; + +static int append_bit(struct hdlc_proc *hdlc, uint8_t bit, int ignore) +{ + memmove(hdlc->history+1, hdlc->history, sizeof(hdlc->history)-1); + hdlc->history[0] = bit; + if (ignore) + return -1; + + memmove(hdlc->next_outbyte+1, hdlc->next_outbyte, sizeof(hdlc->next_outbyte)-1); + hdlc->next_outbyte[0] = bit; + hdlc->num_bits++; + + if (hdlc->num_bits == 8) { + pbit_t out; + /* generate one output byte */ + osmo_ubit2pbit_ext(&out, 0, hdlc->next_outbyte, 0, 8, 0); + hdlc->num_bits = 0; + return out; + } + + return -1; +} + +static int process_hdlc_bit(struct hdlc_proc *hdlc, uint8_t bit) +{ + int ignore = 0; + int out, flag = 0; + + DEBUGP("bit=%u, history_in = %s, ", bit, osmo_ubit_dump(hdlc->history, sizeof(hdlc->history))); + + switch (hdlc->state) { + case STATE_FLAG_WAIT_ZERO: + if (bit == 0) { + DEBUGP("F "); + flag = 1; + hdlc->state = STATE_PAYLOAD; + } else { + hdlc->state = STATE_INIT; + } + ignore = 1; + hdlc->num_bits = 0; + break; + default: + if (!memcmp(five_ones, hdlc->history, sizeof(five_ones))) { + if (bit == 1) { + //DEBUGP("F "); + hdlc->state = STATE_FLAG_WAIT_ZERO; + ignore = 1; + } else { + /* discard bit */ + ignore = 1; + } + } + break; + } + out = append_bit(hdlc, bit, ignore); + DEBUGP("history_out = %s", osmo_ubit_dump(hdlc->history, sizeof(hdlc->history))); + if (out > 0) + DEBUGP(", out 0x%02x\n", out); + else + DEBUGP("\n"); + + if (flag) + return -123; + else + return out; +} + +int process_raw_hdlc(struct hdlc_proc *hdlc, uint8_t *data, unsigned int len) +{ + unsigned int i; + int out; + static int last_out; + + for (i = 0; i < len; i ++) { + out = process_hdlc_bit(hdlc, data[i]); + if (out == -123) { + /* suppress repeating Flag characters */ + if (last_out != out) + printf("\nF "); + last_out = out; + } else if (out >= 0) { + /* suppress 0xAA and 0x55 bit pattern */ + if (out != 0xaa && out != 0x55) + printf("%02x ", out); + last_out = out; + } + } + return 0; +} diff --git a/src/hdlc.h b/src/hdlc.h new file mode 100644 index 0000000..10ec8e2 --- /dev/null +++ b/src/hdlc.h @@ -0,0 +1,18 @@ +#pragma once + +#include <osmocom/core/bits.h> + +enum hdlc_proc_state { + STATE_INIT, + STATE_FLAG_WAIT_ZERO, + STATE_PAYLOAD, +}; + +struct hdlc_proc { + ubit_t history[8]; + ubit_t next_outbyte[8]; + enum hdlc_proc_state state; + uint8_t num_bits; +}; + +int process_raw_hdlc(struct hdlc_proc *hdlc, uint8_t *data, unsigned int len); |