/* isp_frame.c - AVR068 serial frames support. */ /* avr.isp - Serial programming AVR module. {{{ * * Copyright (C) 2009 Nicolas Schodet * * APBTeam: * Web: http://apbteam.org/ * Email: team AT apbteam DOT org * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. * * }}} */ #include "common.h" #include "isp_frame.h" #define ISP_FRAME_PROTO_START 27 #define ISP_FRAME_PROTO_TOKEN 14 #define ISP_FRAME_PROTO_ANSWER_CKSUM_ERROR 0xb0 #define ISP_FRAME_PROTO_STATUS_CKSUM_ERROR 0xc1 /** State of frame decoding. */ enum isp_frame_state_t { /** Start state, nothing decoded. */ ISP_FRAME_STATE_START, /** After message started, waiting sequence number. */ ISP_FRAME_STATE_WAIT_SEQ, /** Waiting first length byte. */ ISP_FRAME_STATE_WAIT_LEN_MSB, /** Waiting second length byte. */ ISP_FRAME_STATE_WAIT_LEN_LSB, /** Waiting token. */ ISP_FRAME_STATE_WAIT_TOKEN, /** Reading data. */ ISP_FRAME_STATE_DATA, /** Waiting checksum. */ ISP_FRAME_STATE_WAIT_CKSUM, }; /** Context. */ struct isp_frame_t { /** Current state. */ uint8_t state; /** Message sequence number. */ uint8_t seq; /** Message length. */ uint16_t len; /** Checksum current value. */ uint8_t cksum; /** Buffer to store frame until validated. */ uint8_t buffer[AC_ISP_FRAME_BUFFER_SIZE]; /** Used buffer length. */ uint16_t buffer_len; }; /** Global context. */ static struct isp_frame_t isp_frame_global; /** Process frame in buffer. */ static void isp_frame_process (void); void isp_frame_accept_char (uint8_t c) { switch (isp_frame_global.state) { case ISP_FRAME_STATE_START: if (c == ISP_FRAME_PROTO_START) { isp_frame_global.cksum = ISP_FRAME_PROTO_START; isp_frame_global.state++; } break; case ISP_FRAME_STATE_WAIT_SEQ: isp_frame_global.cksum ^= c; isp_frame_global.seq = c; isp_frame_global.state++; break; case ISP_FRAME_STATE_WAIT_LEN_MSB: isp_frame_global.cksum ^= c; isp_frame_global.len = c << 8; isp_frame_global.state++; break; case ISP_FRAME_STATE_WAIT_LEN_LSB: isp_frame_global.cksum ^= c; isp_frame_global.len |= c; isp_frame_global.buffer_len = 0; if (isp_frame_global.len == 0 || isp_frame_global.len > AC_ISP_FRAME_BUFFER_SIZE) isp_frame_global.state = ISP_FRAME_STATE_START; else isp_frame_global.state++; break; case ISP_FRAME_STATE_WAIT_TOKEN: if (c == ISP_FRAME_PROTO_TOKEN) { isp_frame_global.cksum ^= c; isp_frame_global.state++; } else isp_frame_global.state = ISP_FRAME_STATE_START; break; case ISP_FRAME_STATE_DATA: isp_frame_global.cksum ^= c; isp_frame_global.buffer[isp_frame_global.buffer_len++] = c; if (isp_frame_global.buffer_len == isp_frame_global.len) isp_frame_global.state++; break; case ISP_FRAME_STATE_WAIT_CKSUM: isp_frame_global.cksum ^= c; isp_frame_global.state = ISP_FRAME_STATE_START; isp_frame_process (); break; } } void isp_frame_send_frame (uint8_t *data, uint16_t len) { uint8_t cksum; AC_ISP_FRAME_SEND_CHAR (ISP_FRAME_PROTO_START); cksum = ISP_FRAME_PROTO_START; AC_ISP_FRAME_SEND_CHAR (isp_frame_global.seq); cksum ^= isp_frame_global.seq; AC_ISP_FRAME_SEND_CHAR (len >> 8); cksum ^= len >> 8; AC_ISP_FRAME_SEND_CHAR (len & 0xff); cksum ^= len & 0xff; AC_ISP_FRAME_SEND_CHAR (ISP_FRAME_PROTO_TOKEN); cksum ^= ISP_FRAME_PROTO_TOKEN; for (; len; len--) { AC_ISP_FRAME_SEND_CHAR (*data); cksum ^= *data; data++; } AC_ISP_FRAME_SEND_CHAR (cksum); } static void isp_frame_process (void) { if (isp_frame_global.cksum != 0) { /* Bad checksum. */ uint8_t answer[2]; answer[0] = ISP_FRAME_PROTO_ANSWER_CKSUM_ERROR; answer[1] = ISP_FRAME_PROTO_STATUS_CKSUM_ERROR; isp_frame_send_frame (answer, 2); } else { AC_ISP_FRAME_ACCEPT_FRAME (isp_frame_global.buffer, isp_frame_global.buffer_len); } }