+++ /dev/null
-/**
- * \file
- * <!--
- * Copyright 2007 Develer S.r.l. (http://www.develer.com/)
- * -->
- *
- * \version $Id: pocketbus.c 20131 2007-12-13 17:39:55Z batt $
- *
- * \author Francesco Sacchi <batt@develer.com>
- *
- * \brief pocketBus protocol implementation.
- *
- * pocketBus protocol is a simple strictly master-slave protocol, usable
- * in embedded systems.
- * pocketBus frame is as follows:
- * <pre>
- * +----------------------------------------+
- * | STX | VER | ADDR | PAYLOAD | CKS | ETX |
- * +----------------------------------------+
- * | | | | | | |
- * + 1B + 1B + 2B + N Byte + 2B + 1B +
- * </pre>
- *
- * - STX, 1 byte (0x02), packet start
- * - VER, 1 byte, packet version
- * - ADDR, 2 byte, slave address
- * - PAYLOAD, N byte, data field
- * - CKS, 2 byte, checksum
- * - ETX, 1 byte, (0x03) packet end
- *
- * Protocol parsing start on STX reception. When the receiving routine
- * finds an STX char, it starts to read characters from the bus
- * until an ETX is received. Once a packet is received,
- * the parser checks packet correctness and checksum. If all is OK
- * the payload is returned.
- *
- * STX (0x02), ETX(0x03) and ESC(0x1B) are special characters and cannot be
- * transmitted inside payload without escaping them.
- * To escape a character you must precede it by the ESC char.
- * E.G. STX -> ESC + STX
- * ETX -> ESC + ETX
- * ESC -> ESC + ESC
- *
- * In the ADDR field is always specified the slave address.
- * In the case of master trasmitting, ADDR contains the slave destination
- * address.
- * In case of slave replying, ADDR contains the slave address itself.
- * Thus, the master device does not have an address. Packet must be routed to
- * master by hardware bus design.
- *
- * The checksum algorithm used is rotating hash algortihm, quite simple but more
- * reliable than simple checksum.
- * The checksum in computed on all fields excluding STX, ETX and CHK fields itself.
- * Checksum is computed on the packet *before* escaping.
- * Escape sequence counts for 1 character only (the escaped one).
- */
-
-#include "pocketbus.h"
-
-#include <cfg/macros.h>
-#include <cfg/debug.h>
-
-#include <kern/kfile.h>
-
-#include <mware/byteorder.h>
-
-#include <string.h>
-
-/**
- * Send a character over pocketBus channel stream, handling escape mode.
- */
-void pocketbus_putchar(struct PocketBusCtx *ctx, uint8_t c)
-{
- /* Update checksum */
- rotating_update1(c, &ctx->out_cks);
-
- /* Escape characters with special meaning */
- if (c == POCKETBUS_ESC || c == POCKETBUS_STX || c == POCKETBUS_ETX)
- kfile_putc(POCKETBUS_ESC, ctx->fd);
-
- kfile_putc(c, ctx->fd);
-}
-
-/**
- * Send pocketBus packet header.
- */
-void pocketbus_begin(struct PocketBusCtx *ctx, pocketbus_addr_t addr)
-{
- PocketBusHdr hdr;
-
- hdr.ver = POCKETBUS_VER;
- hdr.addr = cpu_to_be16(addr);
- rotating_init(&ctx->out_cks);
-
- /* Send STX */
- kfile_putc(POCKETBUS_STX, ctx->fd);
-
- /* Send header */
- pocketbus_write(ctx, &hdr, sizeof(hdr));
-}
-
-/**
- * Send buffer \a _data over bus, handling escape.
- */
-void pocketbus_write(struct PocketBusCtx *ctx, const void *_data, size_t len)
-{
- const uint8_t *data = (const uint8_t *)_data;
-
- while (len--)
- pocketbus_putchar(ctx, *data++);
-}
-
-/**
- * Send pocketBus packet tail.
- */
-void pocketbus_end(struct PocketBusCtx *ctx)
-{
- /* Send checksum */
- rotating_t cks = cpu_to_be16(ctx->out_cks);
- pocketbus_write(ctx, &cks, sizeof(cks));
-
- /* Send ETX */
- kfile_putc(POCKETBUS_ETX, ctx->fd);
-}
-
-/**
- * Send buffer of \a data to address \a addr with a pocketBus packet over channel stream.
- */
-void pocketbus_send(struct PocketBusCtx *ctx, pocketbus_addr_t addr, const void *data, size_t len)
-{
- pocketbus_begin(ctx, addr);
-
- /* Send data */
- pocketbus_write(ctx, data, len);
-
- pocketbus_end(ctx);
-}
-
-
-/**
- * Try to read a packet from the pocketBus.
- * \return true if a packet is received, false otherwise.
- */
-bool pocketbus_recv(struct PocketBusCtx *ctx, struct PocketMsg *msg)
-{
- int c;
-
- /* Process incoming characters until buffer is not empty */
- while ((c = kfile_getc(ctx->fd)) != EOF)
- {
- /* Look for STX char */
- if (c == POCKETBUS_STX && !ctx->escape)
- {
- /* When an STX is found, inconditionally start a new packet */
- if (ctx->sync)
- kprintf("pocketBus double sync!\n");
-
- ctx->sync = true;
- ctx->len = 0;
- rotating_init(&ctx->in_cks);
- continue;
- }
-
- if (ctx->sync)
- {
- /* Handle escape mode */
- if (c == POCKETBUS_ESC && !ctx->escape)
- {
- ctx->escape = true;
- continue;
- }
-
- /* Handle message end */
- if (c == POCKETBUS_ETX && !ctx->escape)
- {
- ctx->sync = false;
-
- /* Check minimum size */
- if (ctx->len < sizeof(PocketBusHdr) + sizeof(rotating_t))
- {
- kprintf("pocketBus short pkt!\n");
- continue;
- }
-
- /* Remove checksum bytes from packet len */
- ctx->len -= sizeof(rotating_t);
-
- /* Compute checksum */
- rotating_update(ctx->buf, ctx->len, &ctx->in_cks);
- rotating_t recv_cks = be16_to_cpu(*((rotating_t *)(ctx->buf + ctx->len)));
-
- /* Checksum check */
- if (recv_cks == ctx->in_cks)
- {
- PocketBusHdr *hdr = (PocketBusHdr *)(ctx->buf);
- /* Check packet version */
- if (hdr->ver == POCKETBUS_VER)
- {
- /* Packet received, set msg fields */
- msg->payload = ctx->buf + sizeof(PocketBusHdr);
- msg->addr = be16_to_cpu(hdr->addr);
- msg->len = ctx->len - sizeof(PocketBusHdr);
- msg->ctx = ctx;
- return true;
- }
- else
- {
- kprintf("pocketBus version mismatch, here[%d], there[%d]\n", POCKETBUS_VER, hdr->ver);
- continue;
- }
- }
- else
- {
- kprintf("pocketBus cks error, here[%04X], there[%04X]\n", ctx->in_cks, recv_cks);
- continue;
- }
-
- }
-
- ctx->escape = false;
-
- /* Check buffer overflow: simply ignore
- received data and go to unsynced state. */
- if (ctx->len >= CONFIG_POCKETBUS_BUFLEN)
- {
- kprintf("pocketBus buffer overflow\n");
- ctx->sync = false;
- continue;
- }
-
- /* Put received data in the buffer */
- ctx->buf[ctx->len] = c;
- ctx->len++;
- }
- }
-
- /*
- * Check stream status.
- */
- if (kfile_error(ctx->fd))
- {
- TRACEMSG("fd status[%04X]", kfile_error(ctx->fd));
- kfile_clearerr(ctx->fd);
- }
-
- return false;
-}
-
-
-/**
- * Initialize pocketBus protocol handler.
- */
-void pocketbus_init(struct PocketBusCtx *ctx, struct KFile *fd)
-{
- ASSERT(ctx);
- ASSERT(fd);
-
- memset(ctx, 0, sizeof(*ctx));
- ctx->fd = fd;
-}
projects / bertos.git / blobdiff