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packages/utils/ucmb/microcontroller_examples/atmel_avr8_optimized/ucmb.c
mb aab089612f Update the optimized AVR8 example implementation. 
git-svn-id: svn://svn.openwrt.org/openwrt/packages@16532 3c298f89-4303-0410-b956-a3cf2f4a3e73
2009-06-21 13:26:37 +00:00

531 lines
17 KiB
C
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/*
* Microcontroller message bus
* uc-side slave implementation for Atmel AVR8
*
* The gcc compiler always treats multi-byte variables as litte-endian.
* So no explicit endianness conversions are done on the message header,
* footer and status data structures.
*
* This hotpath-assembly implementation is about twice as fast
* as the C implementation.
*
* Copyright (C) 2009 Michael Buesch <mb@bu3sch.de>
*
* 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.
*/
#include "ucmb.h"
#include <stdint.h>
#include <avr/io.h>
#include <avr/interrupt.h>
#include <avr/pgmspace.h>
#include <avr/wdt.h>
#ifndef __GNUC__
# error "Need the GNU C compiler"
#endif
#undef __naked
#define __naked __attribute__((__naked__))
#undef __used
#define __used __attribute__((__used__))
#undef __noret
#define __noret __attribute__((__noreturn__))
#undef offsetof
#define offsetof(type, member) ((size_t)&((type *)0)->member)
#undef unlikely
#define unlikely(x) __builtin_expect(!!(x), 0)
#undef mb
#define mb() __asm__ __volatile__("" : : : "memory") /* memory barrier */
#ifndef ucmb_errorlog
# define ucmb_errorlog(message) do { /* nothing */ } while (0)
#endif
struct ucmb_message_hdr {
uint16_t magic; /* UCMB_MAGIC */
uint16_t len; /* Payload length (excluding header and footer) */
} __attribute__((packed));
struct ucmb_message_footer {
uint16_t crc; /* CRC of the header + payload. */
} __attribute__((packed));
struct ucmb_status {
uint16_t magic; /* UCMB_MAGIC */
uint16_t code; /* enum ucmb_status_code */
} __attribute__((packed));
#define UCMB_MAGIC 0x1337
enum ucmb_status_code {
UCMB_STAT_OK = 0,
UCMB_STAT_EPROTO, /* Protocol format error */
UCMB_STAT_ENOMEM, /* Out of memory */
UCMB_STAT_E2BIG, /* Message too big */
UCMB_STAT_ECRC, /* CRC error */
};
static uint8_t ucmb_buf[sizeof(struct ucmb_message_hdr) +
UCMB_MAX_MSG_LEN +
sizeof(struct ucmb_message_footer)] __used;
static uint16_t ucmb_buf_ptr __used;
static struct ucmb_status status_buf __used;
static uint16_t ucmb_send_message_len __used;
static uint8_t ucmb_received_message;
/* The current IRQ handler */
static void (*ucmb_interrupt_handler)(void) __used;
/* Polynomial: x^16 + x^15 + x^2 + 1 */
static const prog_uint16_t crc16_table[256] = {
0x0000, 0xC0C1, 0xC181, 0x0140, 0xC301, 0x03C0, 0x0280, 0xC241,
0xC601, 0x06C0, 0x0780, 0xC741, 0x0500, 0xC5C1, 0xC481, 0x0440,
0xCC01, 0x0CC0, 0x0D80, 0xCD41, 0x0F00, 0xCFC1, 0xCE81, 0x0E40,
0x0A00, 0xCAC1, 0xCB81, 0x0B40, 0xC901, 0x09C0, 0x0880, 0xC841,
0xD801, 0x18C0, 0x1980, 0xD941, 0x1B00, 0xDBC1, 0xDA81, 0x1A40,
0x1E00, 0xDEC1, 0xDF81, 0x1F40, 0xDD01, 0x1DC0, 0x1C80, 0xDC41,
0x1400, 0xD4C1, 0xD581, 0x1540, 0xD701, 0x17C0, 0x1680, 0xD641,
0xD201, 0x12C0, 0x1380, 0xD341, 0x1100, 0xD1C1, 0xD081, 0x1040,
0xF001, 0x30C0, 0x3180, 0xF141, 0x3300, 0xF3C1, 0xF281, 0x3240,
0x3600, 0xF6C1, 0xF781, 0x3740, 0xF501, 0x35C0, 0x3480, 0xF441,
0x3C00, 0xFCC1, 0xFD81, 0x3D40, 0xFF01, 0x3FC0, 0x3E80, 0xFE41,
0xFA01, 0x3AC0, 0x3B80, 0xFB41, 0x3900, 0xF9C1, 0xF881, 0x3840,
0x2800, 0xE8C1, 0xE981, 0x2940, 0xEB01, 0x2BC0, 0x2A80, 0xEA41,
0xEE01, 0x2EC0, 0x2F80, 0xEF41, 0x2D00, 0xEDC1, 0xEC81, 0x2C40,
0xE401, 0x24C0, 0x2580, 0xE541, 0x2700, 0xE7C1, 0xE681, 0x2640,
0x2200, 0xE2C1, 0xE381, 0x2340, 0xE101, 0x21C0, 0x2080, 0xE041,
0xA001, 0x60C0, 0x6180, 0xA141, 0x6300, 0xA3C1, 0xA281, 0x6240,
0x6600, 0xA6C1, 0xA781, 0x6740, 0xA501, 0x65C0, 0x6480, 0xA441,
0x6C00, 0xACC1, 0xAD81, 0x6D40, 0xAF01, 0x6FC0, 0x6E80, 0xAE41,
0xAA01, 0x6AC0, 0x6B80, 0xAB41, 0x6900, 0xA9C1, 0xA881, 0x6840,
0x7800, 0xB8C1, 0xB981, 0x7940, 0xBB01, 0x7BC0, 0x7A80, 0xBA41,
0xBE01, 0x7EC0, 0x7F80, 0xBF41, 0x7D00, 0xBDC1, 0xBC81, 0x7C40,
0xB401, 0x74C0, 0x7580, 0xB541, 0x7700, 0xB7C1, 0xB681, 0x7640,
0x7200, 0xB2C1, 0xB381, 0x7340, 0xB101, 0x71C0, 0x7080, 0xB041,
0x5000, 0x90C1, 0x9181, 0x5140, 0x9301, 0x53C0, 0x5280, 0x9241,
0x9601, 0x56C0, 0x5780, 0x9741, 0x5500, 0x95C1, 0x9481, 0x5440,
0x9C01, 0x5CC0, 0x5D80, 0x9D41, 0x5F00, 0x9FC1, 0x9E81, 0x5E40,
0x5A00, 0x9AC1, 0x9B81, 0x5B40, 0x9901, 0x59C0, 0x5880, 0x9841,
0x8801, 0x48C0, 0x4980, 0x8941, 0x4B00, 0x8BC1, 0x8A81, 0x4A40,
0x4E00, 0x8EC1, 0x8F81, 0x4F40, 0x8D01, 0x4DC0, 0x4C80, 0x8C41,
0x4400, 0x84C1, 0x8581, 0x4540, 0x8701, 0x47C0, 0x4680, 0x8641,
0x8201, 0x42C0, 0x4380, 0x8341, 0x4100, 0x81C1, 0x8081, 0x4040
};
static inline uint16_t crc16_block_update(uint16_t crc, const void *_data, uint16_t size)
{
const uint8_t *data = _data;
uint8_t offset;
while (size--) {
wdt_reset();
offset = crc ^ *data;
crc = (crc >> 8) ^ pgm_read_word(&crc16_table[offset]);
data++;
}
return crc;
}
static inline uint16_t ucmb_calc_msg_buffer_crc(void)
{
const struct ucmb_message_hdr *hdr;
uint16_t crc = 0xFFFF;
hdr = (const struct ucmb_message_hdr *)ucmb_buf;
crc = crc16_block_update(crc, ucmb_buf,
sizeof(struct ucmb_message_hdr) + hdr->len);
crc ^= 0xFFFF;
return crc;
}
/* The generic interrupt handler.
* This just branches to the state specific handler.
*/
ISR(SPI_STC_vect) __naked;
ISR(SPI_STC_vect)
{
__asm__ __volatile__(
" ; UCMB generic interrupt handler \n"
" push __tmp_reg__ \n"
" in __tmp_reg__, __SREG__ \n"
" push r30 \n"
" push r31 \n"
" lds r30, ucmb_interrupt_handler + 0 \n"
" lds r31, ucmb_interrupt_handler + 1 \n"
" ijmp ; Jump to the real handler \n"
);
}
#define UCMB_IRQ_EPILOGUE \
" ; UCMB interrupt epilogue (start) \n"\
" pop r31 \n"\
" pop r30 \n"\
" out __SREG__, __tmp_reg__ \n"\
" pop __tmp_reg__ \n"\
" reti \n"\
" ; UCMB interrupt epilogue (end) \n"
static void __naked __used ucmb_handler_LISTEN(void)
{
__asm__ __volatile__(
" push r16 \n"
" push r17 \n"
" push r18 \n"
" lds r16, ucmb_buf_ptr + 0 \n"
" lds r17, ucmb_buf_ptr + 1 \n"
" ldi r18, hi8(%[sizeof_buf]) \n"
" cpi r16, lo8(%[sizeof_buf]) \n"
" cpc r17, r18 \n"
" in r18, %[_SPDR] \n"
" brsh 1f ; overflow \n"
" ; Store SPDR in the buffer \n"
" movw r30, r16 \n"
" subi r30, lo8(-(ucmb_buf)) \n"
" sbci r31, hi8(-(ucmb_buf)) \n"
" st Z, r18 \n"
"1: \n"
" ; Increment the buffer pointer \n"
" subi r16, lo8(-1) \n"
" sbci r17, hi8(-1) \n"
" sts ucmb_buf_ptr + 0, r16 \n"
" sts ucmb_buf_ptr + 1, r17 \n"
" cpi r17, 0 \n"
" brne 1f \n"
" cpi r16, %[sizeof_msg_hdr] \n"
" breq hdr_sanity_check ; buf_ptr == hdrlen \n"
" brlo st_listen_out ; buf_ptr < hdrlen \n"
"1: \n"
" ; Get payload length from header \n"
" lds r30, (ucmb_buf + %[offsetof_hdr_len] + 0) \n"
" lds r31, (ucmb_buf + %[offsetof_hdr_len] + 1) \n"
" ; Add header and footer length to get full length \n"
" subi r30, lo8(-(%[sizeof_msg_hdr] + %[sizeof_msg_footer])) \n"
" sbci r31, hi8(-(%[sizeof_msg_hdr] + %[sizeof_msg_footer])) \n"
" ; Check if we have the full packet \n"
" cp r30, r16 \n"
" cpc r31, r17 \n"
" breq st_listen_have_full_packet \n"
"st_listen_out: \n"
" pop r18 \n"
" pop r17 \n"
" pop r16 \n"
UCMB_IRQ_EPILOGUE /* reti */
" \n"
"hdr_sanity_check: \n"
" lds r30, (ucmb_buf + %[offsetof_hdr_magic] + 0) \n"
" lds r31, (ucmb_buf + %[offsetof_hdr_magic] + 1) \n"
" ldi r18, hi8(%[_UCMB_MAGIC]) \n"
" cpi r30, lo8(%[_UCMB_MAGIC]) \n"
" cpc r31, r18 \n"
" brne invalid_hdr_magic \n"
" lds r30, (ucmb_buf + %[offsetof_hdr_len] + 0) \n"
" lds r31, (ucmb_buf + %[offsetof_hdr_len] + 1) \n"
" ldi r18, hi8(0x8001) \n"
" cpi r30, lo8(0x8001) \n"
" cpc r31, r18 \n"
" brsh bogus_payload_len \n"
" rjmp st_listen_out \n"
" \n"
"invalid_hdr_magic: \n"
" ; Invalid magic number in the packet header. Reset. \n"
"bogus_payload_len: \n"
" ; Bogus payload length in packet header. Reset. \n"
" clr r18 \n"
" sts ucmb_buf_ptr + 0, r18 \n"
" sts ucmb_buf_ptr + 1, r18 \n"
" rjmp st_listen_out \n"
" \n"
"st_listen_have_full_packet: \n"
" ; We have the full packet. Any SPI transfer is stopped \n"
" ; while we are processing the packet, so this \n"
" ; is a slowpath. \n"
" ; Disable SPI and pass control to ucmb_work to \n"
" ; handle the message. \n"
" cbi %[_SPCR], %[_SPIE] \n"
" ldi r18, 1 \n"
" sts ucmb_received_message, r18 \n"
" rjmp st_listen_out \n"
: /* none */
: [sizeof_buf] "i" (sizeof(ucmb_buf))
, [sizeof_msg_hdr] "M" (sizeof(struct ucmb_message_hdr))
, [sizeof_msg_footer] "M" (sizeof(struct ucmb_message_footer))
, [offsetof_hdr_magic] "M" (offsetof(struct ucmb_message_hdr, magic))
, [offsetof_hdr_len] "M" (offsetof(struct ucmb_message_hdr, len))
, [_SPDR] "M" (_SFR_IO_ADDR(SPDR))
, [_SPCR] "M" (_SFR_IO_ADDR(SPCR))
, [_SPIE] "i" (SPIE)
, [_UCMB_MAGIC] "i" (UCMB_MAGIC)
: "memory"
);
}
static void __naked __used ucmb_handler_SENDSTATUS(void)
{
__asm__ __volatile__(
" push r16 \n"
/*" push r17 \n" */
" push r18 \n"
" lds r16, ucmb_buf_ptr + 0 \n"
" cpi r16, %[sizeof_ucmb_status] \n"
" brsh 1f ; This is the trailing byte \n"
" ; Write the next byte from status_buf to SPDR \n"
" mov r30, r16 \n"
" clr r31 \n"
" subi r30, lo8(-(status_buf)) \n"
" sbci r31, hi8(-(status_buf)) \n"
" ld r18, Z \n"
" out %[_SPDR], r18 \n"
"1: \n"
" subi r16, lo8(-1) \n"
" sts ucmb_buf_ptr + 0, r16 \n"
" cpi r16, (%[sizeof_ucmb_status] + 1) \n"
" brne st_sendstatus_out \n"
" ; Finished. Sent all status_buf bytes + trailing byte. \n"
" clr r18 \n"
" sts ucmb_buf_ptr + 0, r18 \n"
" ; Switch back to listening state... \n"
" ldi r18, lo8(gs(ucmb_handler_LISTEN)) \n"
" sts ucmb_interrupt_handler + 0, r18 \n"
" ldi r18, hi8(gs(ucmb_handler_LISTEN)) \n"
" sts ucmb_interrupt_handler + 1, r18 \n"
" ; ...if we have no pending transmission \n"
" lds r30, ucmb_send_message_len + 0 \n"
" lds r31, ucmb_send_message_len + 1 \n"
" clr r18 \n"
" cpi r30, 0 \n"
" cpc r31, r18 \n"
" breq st_sendstatus_out \n"
" ; Switch status to SENDMESSAGE and send the first byte. \n"
" ldi r18, lo8(gs(ucmb_handler_SENDMESSAGE)) \n"
" sts ucmb_interrupt_handler + 0, r18 \n"
" ldi r18, hi8(gs(ucmb_handler_SENDMESSAGE)) \n"
" sts ucmb_interrupt_handler + 1, r18 \n"
" ; Send the first byte \n"
" lds r18, ucmb_buf + 0 \n"
" out %[_SPDR], r18 \n"
" ldi r18, 1 \n"
" sts ucmb_buf_ptr + 0, r18 \n"
"st_sendstatus_out: \n"
" pop r18 \n"
/*" pop r17 \n"*/
" pop r16 \n"
UCMB_IRQ_EPILOGUE /* reti */
: /* none */
: [sizeof_ucmb_status] "M" (sizeof(struct ucmb_status))
, [_SPDR] "M" (_SFR_IO_ADDR(SPDR))
: "memory"
);
}
static void __naked __used ucmb_handler_SENDMESSAGE(void)
{
__asm__ __volatile__(
" push r16 \n"
" push r17 \n"
" push r18 \n"
" lds r16, ucmb_buf_ptr + 0 \n"
" lds r17, ucmb_buf_ptr + 1 \n"
" lds r30, ucmb_send_message_len + 0 \n"
" lds r31, ucmb_send_message_len + 1 \n"
" cp r16, r30 \n"
" cpc r17, r31 \n"
" brsh 1f ; This is the trailing byte \n"
" movw r30, r16 \n"
" subi r30, lo8(-(ucmb_buf)) \n"
" sbci r31, hi8(-(ucmb_buf)) \n"
" ld r18, Z \n"
" out %[_SPDR], r18 \n"
"1: \n"
" subi r16, lo8(-1) \n"
" sbci r17, hi8(-1) \n"
" sts ucmb_buf_ptr + 0, r16 \n"
" sts ucmb_buf_ptr + 1, r17 \n"
" lds r30, ucmb_send_message_len + 0 \n"
" lds r31, ucmb_send_message_len + 1 \n"
" subi r30, lo8(-1) \n"
" sbci r31, hi8(-1) \n"
" cp r16, r30 \n"
" cpc r17, r31 \n"
" brne st_sendmessage_out \n"
" ; Message + trailing byte processed. Retrieve status. \n"
" clr r18 \n"
" sts ucmb_buf_ptr + 0, r18 \n"
" sts ucmb_buf_ptr + 1, r18 \n"
" ldi r18, lo8(gs(ucmb_handler_RETRSTATUS)) \n"
" sts ucmb_interrupt_handler + 0, r18 \n"
" ldi r18, hi8(gs(ucmb_handler_RETRSTATUS)) \n"
" sts ucmb_interrupt_handler + 1, r18 \n"
"st_sendmessage_out: \n"
" pop r18 \n"
" pop r17 \n"
" pop r16 \n"
UCMB_IRQ_EPILOGUE /* reti */
: /* none */
: [_SPDR] "M" (_SFR_IO_ADDR(SPDR))
: "memory"
);
}
static void __naked __used ucmb_handler_RETRSTATUS(void)
{
__asm__ __volatile__(
" push r16 \n"
/*" push r17 \n"*/
" push r18 \n"
" in r18, %[_SPDR] \n"
" lds r16, ucmb_buf_ptr + 0 \n"
" mov r30, r16 \n"
" clr r31 \n"
" subi r30, lo8(-(status_buf)) \n"
" sbci r31, hi8(-(status_buf)) \n"
" st Z, r18 \n"
" subi r16, -1 \n"
" sts ucmb_buf_ptr + 0, r16 \n"
" cpi r16, %[sizeof_ucmb_status] \n"
" brne st_retrstatus_out \n"
" ; Completely received the status \n"
" clr r16 \n"
" sts ucmb_buf_ptr + 0, r16 \n"
" ; Switch back to listening state... \n"
" ldi r18, lo8(gs(ucmb_handler_LISTEN)) \n"
" sts ucmb_interrupt_handler + 0, r18 \n"
" ldi r18, hi8(gs(ucmb_handler_LISTEN)) \n"
" sts ucmb_interrupt_handler + 1, r18 \n"
" ; Check status-report magic value \n"
" lds r30, (status_buf + %[offsetof_status_magic] + 0) \n"
" lds r31, (status_buf + %[offsetof_status_magic] + 1) \n"
" ldi r18, hi8(%[_UCMB_MAGIC]) \n"
" cpi r30, lo8(%[_UCMB_MAGIC]) \n"
" cpc r31, r18 \n"
" brne invalid_status_magic \n"
" ; Check status-report error code \n"
" lds r30, (status_buf + %[offsetof_status_code] + 0) \n"
" lds r31, (status_buf + %[offsetof_status_code] + 1) \n"
" ldi r18, hi8(%[_UCMB_STAT_OK]) \n"
" cpi r30, lo8(%[_UCMB_STAT_OK]) \n"
" cpc r31, r18 \n"
" brne faulty_status_code \n"
"st_retrstatus_out: \n"
" pop r18 \n"
/*" pop r17 \n"*/
" pop r16 \n"
UCMB_IRQ_EPILOGUE /* reti */
" \n"
"invalid_status_magic: \n"
"faulty_status_code: \n"
" ; Branch to the C error handler \n"
" ; The handler does not return, so we don't need to \n"
" ; push/pop the registers. \n"
" clr __zero_reg__ \n"
" rjmp ucmb_received_faulty_status \n"
: /* none */
: [sizeof_ucmb_status] "M" (sizeof(struct ucmb_status))
, [offsetof_status_magic] "M" (offsetof(struct ucmb_status, magic))
, [offsetof_status_code] "M" (offsetof(struct ucmb_status, code))
, [_SPDR] "M" (_SFR_IO_ADDR(SPDR))
, [_UCMB_MAGIC] "i" (UCMB_MAGIC)
, [_UCMB_STAT_OK] "i" (UCMB_STAT_OK)
: "memory"
);
}
/* We received a status report with an error condition.
* This is called from assembly code. The function does not return. */
static void __used __noret ucmb_received_faulty_status(void)
{
/* The master sent us a status report with an error code.
* Something's wrong with us. Print a status message and
* get caught by the watchdog, yummy.
*/
cli();
wdt_disable();
wdt_enable(WDTO_15MS);
ucmb_errorlog("UCMB: Received faulty status report. Triggering reset.");
while (1) {
/* "It's Coming Right For Us!" */
}
}
void ucmb_work(void)
{
struct ucmb_message_hdr *hdr;
struct ucmb_message_footer *footer;
uint16_t payload_len;
if (!ucmb_received_message)
return;
hdr = (struct ucmb_message_hdr *)ucmb_buf;
payload_len = hdr->len;
status_buf.magic = UCMB_MAGIC;
status_buf.code = UCMB_STAT_OK;
if (unlikely(ucmb_buf_ptr > sizeof(ucmb_buf))) {
/* Message is way too big and was truncated. */
status_buf.code = UCMB_STAT_E2BIG;
} else {
footer = (struct ucmb_message_footer *)(
ucmb_buf + sizeof(struct ucmb_message_hdr) +
payload_len);
if (ucmb_calc_msg_buffer_crc() != footer->crc)
status_buf.code = UCMB_STAT_ECRC;
}
ucmb_interrupt_handler = ucmb_handler_SENDSTATUS;
ucmb_buf_ptr = 0;
/* Send the first byte */
SPDR = ((uint8_t *)&status_buf)[ucmb_buf_ptr];
ucmb_buf_ptr++;
if (unlikely(status_buf.code != UCMB_STAT_OK))
goto out; /* Corrupt message. Don't pass it to user code. */
ucmb_send_message_len = ucmb_rx_message(
ucmb_buf + sizeof(struct ucmb_message_hdr),
payload_len);
if (ucmb_send_message_len) {
footer = (struct ucmb_message_footer *)(
ucmb_buf + sizeof(struct ucmb_message_hdr) +
ucmb_send_message_len);
hdr->magic = UCMB_MAGIC;
hdr->len = ucmb_send_message_len;
footer->crc = ucmb_calc_msg_buffer_crc();
ucmb_send_message_len += sizeof(struct ucmb_message_hdr) +
sizeof(struct ucmb_message_footer);
}
out:
ucmb_received_message = 0;
mb();
/* Re-enable SPI */
SPCR |= (1 << SPIE);
}
void ucmb_init(void)
{
ucmb_interrupt_handler = ucmb_handler_LISTEN;
/* SPI slave mode 0 with IRQ enabled. */
DDRB |= (1 << 6/*MISO*/);
DDRB &= ~((1 << 7/*SCK*/) | (1 << 5/*MOSI*/) | (1 << 4/*SS*/));
SPCR = (1 << SPE) | (1 << SPIE) /*| (1 << CPOL) | (1 << CPHA)*/;
(void)SPSR; /* clear state */
(void)SPDR; /* clear state */
}
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