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177 lines
5.4 KiB
C
177 lines
5.4 KiB
C
/*
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* Copyright (C) 1995 Advanced RISC Machines Limited. All rights reserved.
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*
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* This software may be freely used, copied, modified, and distributed
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* provided that the above copyright notice is preserved in all copies of the
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* software.
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*/
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/*-*-C-*-
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*
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* $Revision$
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* $Date$
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*
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* Project: ANGEL
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*
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* Title: Character based packet transmission engine
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*/
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#include <stdarg.h> /* ANSI varargs support */
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#include "angel.h" /* Angel system definitions */
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#include "angel_endian.h" /* Endian independant memory access macros */
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#include "crc.h" /* crc generation definitions and headers */
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#include "rxtx.h"
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#include "channels.h"
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#include "buffers.h"
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#include "logging.h"
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/* definitions to describe the engines state */
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#define N_STX 0x0 /* first 2 bits for N_ */
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#define N_BODY 0x1
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#define N_ETX 0x2
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#define N_IDLE 0x3
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#define N_MASK 0x3 /* mask for the Encapsulator state */
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#define E_PLAIN (0x0 << 2) /* 3rd bit for E_ */
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#define E_ESC (0x1 << 2) /* 3rd bit for E_ */
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#define E_MASK (0x1 << 2) /* mask for the Escaper state */
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#define F_HEAD (0x0 << 3) /* 4th and 5th bits for F_ */
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#define F_DATA (0x1 << 3)
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#define F_CRC (0x1 << 4)
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#define F_MASK (0x3 << 3) /* mask for the Escaper state */
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static unsigned char escape(unsigned char ch_in, struct te_state *txstate);
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void Angel_TxEngineInit(const struct re_config *txconfig,
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const struct data_packet *packet,
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struct te_state *txstate){
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IGNORE(packet);
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txstate->tx_state = N_STX | E_PLAIN | F_HEAD;
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txstate->field_c = 0;
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txstate->encoded = 0;
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txstate->config = txconfig;
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txstate->crc = 0;
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}
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te_status Angel_TxEngine(const struct data_packet *packet,
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struct te_state *txstate,
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unsigned char *tx_ch){
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/* TODO: gaurd on long/bad packets */
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/*
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* encapsulate the packet, framing has been moved from a seperate
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* function into the encapsulation routine as it needed too much
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* inherited state for it to be sensibly located elsewhere
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*/
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switch ((txstate->tx_state) & N_MASK){
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case N_STX:
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#ifdef DO_TRACE
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__rt_trace("txe-stx ");
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#endif
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txstate->tx_state = (txstate->tx_state & ~N_MASK) | N_BODY;
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*tx_ch = txstate->config->stx;
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txstate->field_c = 3; /* set up for the header */
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txstate->crc = startCRC32; /* set up basic crc */
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return TS_IN_PKT;
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case N_BODY:{
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switch (txstate->tx_state & F_MASK) {
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case F_HEAD:
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#ifdef DO_TRACE
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__rt_trace("txe-head ");
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#endif
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if (txstate->field_c == 3) {
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/* send type */
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*tx_ch = escape(packet->type, txstate);
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return TS_IN_PKT;
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}
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else {
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*tx_ch = escape((packet->len >> (txstate->field_c - 1) * 8) & 0xff,
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txstate);
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if (txstate->field_c == 0) {
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/* move on to the next state */
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txstate->tx_state = (txstate->tx_state & ~F_MASK) | F_DATA;
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txstate->field_c = packet->len;
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}
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return TS_IN_PKT;
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}
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case F_DATA:
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#ifdef DO_TRACE
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__rt_trace("txe-data ");
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#endif
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*tx_ch = escape(packet->data[packet->len - txstate->field_c], txstate);
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if (txstate->field_c == 0) {
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/* move on to the next state */
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txstate->tx_state = (txstate->tx_state & ~F_MASK) | F_CRC;
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txstate->field_c = 4;
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}
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return TS_IN_PKT;
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case F_CRC:
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#ifdef DO_TRACE
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__rt_trace("txe-crc ");
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#endif
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*tx_ch = escape((txstate->crc >> ((txstate->field_c - 1) * 8)) & 0xff,
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txstate);
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if (txstate->field_c == 0) {
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#ifdef DO_TRACE
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__rt_trace("txe crc = 0x%x\n", txstate->crc);
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#endif
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/* move on to the next state */
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txstate->tx_state = (txstate->tx_state & ~N_MASK) | N_ETX;
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}
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return TS_IN_PKT;
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}
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}
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case N_ETX:
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#ifdef DO_TRACE
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__rt_trace("txe-etx\n");
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#endif
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txstate->tx_state = (txstate->tx_state & ~N_MASK) | N_IDLE;
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*tx_ch = txstate->config->etx;
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return TS_DONE_PKT;
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default:
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#ifdef DEBUG
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__rt_info("tx default\n");
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#endif
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txstate->tx_state = (txstate->tx_state & ~N_MASK) | N_IDLE;
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return TS_IDLE;
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}
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/* stop a silly -Wall warning */
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return (te_status)-1;
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}
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/*
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* crc generation occurs in the escape function because it is the only
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* place where we know that we're putting a real char into the buffer
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* rather than an escaped one.
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* We must be careful here not to update the crc when we're sending it
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*/
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static unsigned char escape(unsigned char ch_in, struct te_state *txstate) {
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if (((txstate->tx_state) & E_MASK) == E_ESC) {
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/* char has been escaped so send the real char */
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#ifdef DO_TRACE
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__rt_trace("txe-echar ");
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#endif
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txstate->tx_state = (txstate->tx_state & ~E_MASK) | E_PLAIN;
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txstate->field_c--;
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if ((txstate->tx_state & F_MASK) != F_CRC)
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txstate->crc = crc32( &ch_in, 1, txstate->crc);
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return ch_in | serial_ESCAPE;
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}
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if ((ch_in < 32) && ((txstate->config->esc_set & (1 << ch_in)) != 0)) {
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/* char needs escaping */
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#ifdef DO_TRACE
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__rt_trace("txe-esc ");
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#endif
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txstate->tx_state = (txstate->tx_state & ~E_MASK) | E_ESC;
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return txstate->config->esc;
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}
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/* must be a char that can be sent plain */
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txstate->field_c--;
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if ((txstate->tx_state & F_MASK) != F_CRC)
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txstate->crc = crc32(&ch_in, 1, txstate->crc);
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return ch_in;
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}
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/* EOF tx.c */
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