+++ /dev/null
-/*
-Copyright 2010,2011,2012,2013 Jun WAKO <wakojun@gmail.com>
-
-This software is licensed with a Modified BSD License.
-All of this is supposed to be Free Software, Open Source, DFSG-free,
-GPL-compatible, and OK to use in both free and proprietary applications.
-Additions and corrections to this file are welcome.
-
-
-Redistribution and use in source and binary forms, with or without
-modification, are permitted provided that the following conditions are met:
-
-* Redistributions of source code must retain the above copyright
- notice, this list of conditions and the following disclaimer.
-
-* Redistributions in binary form must reproduce the above copyright
- notice, this list of conditions and the following disclaimer in
- the documentation and/or other materials provided with the
- distribution.
-
-* Neither the name of the copyright holders nor the names of
- contributors may be used to endorse or promote products derived
- from this software without specific prior written permission.
-
-THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
-AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
-IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
-ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
-LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
-CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
-SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
-INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
-CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
-ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
-POSSIBILITY OF SUCH DAMAGE.
-*/
-
-#include <stdbool.h>
-#include <avr/io.h>
-#include <avr/interrupt.h>
-#include <util/delay.h>
-#include "ps2.h"
-#include "debug.h"
-
-
-#ifndef PS2_USE_INT
-static uint8_t recv_data(void);
-#endif
-static inline void clock_lo(void);
-static inline void clock_hi(void);
-static inline bool clock_in(void);
-static inline void data_lo(void);
-static inline void data_hi(void);
-static inline bool data_in(void);
-static inline uint16_t wait_clock_lo(uint16_t us);
-static inline uint16_t wait_clock_hi(uint16_t us);
-static inline uint16_t wait_data_lo(uint16_t us);
-static inline uint16_t wait_data_hi(uint16_t us);
-static inline void idle(void);
-static inline void inhibit(void);
-
-
-/*
-Primitive PS/2 Library for AVR
-==============================
-Host side is only supported now.
-
-
-I/O control
------------
-High state is asserted by input with pull up.
-
-
-PS/2 References
----------------
-http://www.computer-engineering.org/ps2protocol/
-http://www.mcamafia.de/pdf/ibm_hitrc07.pdf
-*/
-
-
-#define WAIT(stat, us, err) do { \
- if (!wait_##stat(us)) { \
- ps2_error = err; \
- goto ERROR; \
- } \
-} while (0)
-
-
-uint8_t ps2_error = PS2_ERR_NONE;
-
-
-void ps2_host_init(void)
-{
- // POR(150-2000ms) plus BAT(300-500ms) may take 2.5sec([3]p.20)
- _delay_ms(2500);
-
-#ifdef PS2_USE_INT
- PS2_INT_INIT();
- PS2_INT_ON();
- idle();
-#else
- inhibit();
-#endif
-}
-
-// TODO: send using interrupt if available
-uint8_t ps2_host_send(uint8_t data)
-{
- uint8_t res = 0;
- bool parity = true;
- ps2_error = PS2_ERR_NONE;
-#ifdef PS2_USE_INT
- PS2_INT_OFF();
-#endif
- /* terminate a transmission if we have */
- inhibit();
- _delay_us(200); // at least 100us
-
- /* start bit [1] */
- data_lo();
- clock_hi();
- WAIT(clock_lo, 20000, 10); // may take 15ms at most until device starts clocking
- /* data [2-9] */
- for (uint8_t i = 0; i < 8; i++) {
- _delay_us(15);
- if (data&(1<<i)) {
- parity = !parity;
- data_hi();
- } else {
- data_lo();
- }
- WAIT(clock_hi, 50, 2);
- WAIT(clock_lo, 50, 3);
- }
- /* parity [10] */
- _delay_us(15);
- if (parity) { data_hi(); } else { data_lo(); }
- WAIT(clock_hi, 50, 4);
- WAIT(clock_lo, 50, 5);
- /* stop bit [11] */
- _delay_us(15);
- data_hi();
- /* ack [12] */
- WAIT(data_lo, 50, 6);
- WAIT(clock_lo, 50, 7);
-
- /* wait for idle state */
- WAIT(clock_hi, 50, 8);
- WAIT(data_hi, 50, 9);
-
-#ifdef PS2_USE_INT
- PS2_INT_ON();
-#endif
- res = ps2_host_recv_response();
-ERROR:
-#ifdef PS2_USE_INT
- PS2_INT_ON();
- idle();
-#else
- inhibit();
-#endif
- return res;
-}
-
-#ifndef PS2_USE_INT
-/* receive data when host want else inhibit communication */
-uint8_t ps2_host_recv_response(void)
-{
- // Command might take 20ms to response([3]p.21)
- // TrackPoint might take 25ms ([5]2.7)
- uint8_t data = 0;
- uint8_t try = 200;
- while (try-- && (data = ps2_host_recv())) ;
- return data;
-}
-#endif
-
-#ifndef PS2_USE_INT
-uint8_t ps2_host_recv(void)
-{
- uint8_t data = 0;
-
- /* release lines(idle state) */
- idle();
-
- /* wait start bit */
- wait_clock_lo(100); // TODO: this is enough?
- data = recv_data();
-
- inhibit();
- return data;
-}
-#else
-/* ring buffer to store ps/2 key data */
-#define PBUF_SIZE 32
-static uint8_t pbuf[PBUF_SIZE];
-static uint8_t pbuf_head = 0;
-static uint8_t pbuf_tail = 0;
-static inline void pbuf_enqueue(uint8_t data)
-{
- uint8_t sreg = SREG;
- cli();
- uint8_t next = (pbuf_head + 1) % PBUF_SIZE;
- if (next != pbuf_tail) {
- pbuf[pbuf_head] = data;
- pbuf_head = next;
- } else {
- debug("pbuf: full\n");
- }
- SREG = sreg;
-}
-static inline uint8_t pbuf_dequeue(void)
-{
- uint8_t val = 0;
-
- uint8_t sreg = SREG;
- cli();
- if (pbuf_head != pbuf_tail) {
- val = pbuf[pbuf_tail];
- pbuf_tail = (pbuf_tail + 1) % PBUF_SIZE;
- }
- SREG = sreg;
-
- return val;
-}
-static inline bool pbuf_has_data(void)
-{
- uint8_t sreg = SREG;
- cli();
- bool has_data = (pbuf_head != pbuf_tail);
- SREG = sreg;
- return has_data;
-}
-static inline void pbuf_clear(void)
-{
- uint8_t sreg = SREG;
- cli();
- pbuf_head = pbuf_tail = 0;
- SREG = sreg;
-}
-
-/* get data received by interrupt */
-uint8_t ps2_host_recv(void)
-{
- return pbuf_dequeue();
-}
-
-uint8_t ps2_host_recv_response(void)
-{
- while (!pbuf_has_data()) ;
- return pbuf_dequeue();
-}
-
-ISR(PS2_INT_VECT)
-{
- static enum {
- INIT,
- START,
- BIT0, BIT1, BIT2, BIT3, BIT4, BIT5, BIT6, BIT7,
- PARITY,
- STOP,
- } state = INIT;
- static uint8_t data = 0;
- static uint8_t parity = 1;
-
- // TODO: abort if elapse 100us from previous interrupt
-
- // return unless falling edge
- if (clock_in()) {
- goto RETURN;
- }
-
- state++;
- switch (state) {
- case START:
- if (data_in())
- goto ERROR;
- break;
- case BIT0:
- case BIT1:
- case BIT2:
- case BIT3:
- case BIT4:
- case BIT5:
- case BIT6:
- case BIT7:
- data >>= 1;
- if (data_in()) {
- data |= 0x80;
- parity++;
- }
- break;
- case PARITY:
- if (data_in()) {
- if (!(parity & 0x01))
- goto ERROR;
- } else {
- if (parity & 0x01)
- goto ERROR;
- }
- break;
- case STOP:
- if (!data_in())
- goto ERROR;
- pbuf_enqueue(data);
-//phex(data);
- goto DONE;
- break;
- default:
- goto ERROR;
- }
- goto RETURN;
-ERROR:
- inhibit();
- ps2_error = state;
-DONE:
- state = INIT;
- data = 0;
- parity = 1;
-RETURN:
- return;
-}
-#endif
-
-
-/* send LED state to keyboard */
-void ps2_host_set_led(uint8_t led)
-{
- ps2_host_send(0xED);
- ps2_host_send(led);
-}
-
-
-#ifndef PS2_USE_INT
-/* called after start bit comes */
-static uint8_t recv_data(void)
-{
- uint8_t data = 0;
- bool parity = true;
- ps2_error = PS2_ERR_NONE;
-
- /* start bit [1] */
- WAIT(clock_lo, 1, 1);
- WAIT(data_lo, 1, 2);
- WAIT(clock_hi, 50, 3);
-
- /* data [2-9] */
- for (uint8_t i = 0; i < 8; i++) {
- WAIT(clock_lo, 50, 4);
- if (data_in()) {
- parity = !parity;
- data |= (1<<i);
- }
- WAIT(clock_hi, 50, 5);
- }
-
- /* parity [10] */
- WAIT(clock_lo, 50, 6);
- if (data_in() != parity) {
- ps2_error = PS2_ERR_PARITY;
- goto ERROR;
- }
- WAIT(clock_hi, 50, 7);
-
- /* stop bit [11] */
- WAIT(clock_lo, 50, 8);
- WAIT(data_hi, 1, 9);
- WAIT(clock_hi, 50, 10);
-
- return data;
-ERROR:
- return 0;
-}
-#endif
-
-static inline void clock_lo()
-{
- PS2_CLOCK_PORT &= ~(1<<PS2_CLOCK_BIT);
- PS2_CLOCK_DDR |= (1<<PS2_CLOCK_BIT);
-}
-static inline void clock_hi()
-{
- /* input with pull up */
- PS2_CLOCK_DDR &= ~(1<<PS2_CLOCK_BIT);
- PS2_CLOCK_PORT |= (1<<PS2_CLOCK_BIT);
-}
-static inline bool clock_in()
-{
- PS2_CLOCK_DDR &= ~(1<<PS2_CLOCK_BIT);
- PS2_CLOCK_PORT |= (1<<PS2_CLOCK_BIT);
- _delay_us(1);
- return PS2_CLOCK_PIN&(1<<PS2_CLOCK_BIT);
-}
-static inline void data_lo()
-{
- PS2_DATA_PORT &= ~(1<<PS2_DATA_BIT);
- PS2_DATA_DDR |= (1<<PS2_DATA_BIT);
-}
-static inline void data_hi()
-{
- /* input with pull up */
- PS2_DATA_DDR &= ~(1<<PS2_DATA_BIT);
- PS2_DATA_PORT |= (1<<PS2_DATA_BIT);
-}
-static inline bool data_in()
-{
- PS2_DATA_DDR &= ~(1<<PS2_DATA_BIT);
- PS2_DATA_PORT |= (1<<PS2_DATA_BIT);
- _delay_us(1);
- return PS2_DATA_PIN&(1<<PS2_DATA_BIT);
-}
-
-static inline uint16_t wait_clock_lo(uint16_t us)
-{
- while (clock_in() && us) { asm(""); _delay_us(1); us--; }
- return us;
-}
-static inline uint16_t wait_clock_hi(uint16_t us)
-{
- while (!clock_in() && us) { asm(""); _delay_us(1); us--; }
- return us;
-}
-static inline uint16_t wait_data_lo(uint16_t us)
-{
- while (data_in() && us) { asm(""); _delay_us(1); us--; }
- return us;
-}
-static inline uint16_t wait_data_hi(uint16_t us)
-{
- while (!data_in() && us) { asm(""); _delay_us(1); us--; }
- return us;
-}
-
-/* idle state that device can send */
-static inline void idle(void)
-{
- clock_hi();
- data_hi();
-}
-
-/* inhibit device to send */
-static inline void inhibit(void)
-{
- clock_lo();
- data_hi();
-}
-
-
-/* PS/2 Resources
- *
- * [1] The PS/2 Mouse/Keyboard Protocol
- * http://www.computer-engineering.org/ps2protocol/
- * Concise and thorough primer of PS/2 protocol.
- *
- * [2] Keyboard and Auxiliary Device Controller
- * http://www.mcamafia.de/pdf/ibm_hitrc07.pdf
- * Signal Timing and Format
- *
- * [3] Keyboards(101- and 102-key)
- * http://www.mcamafia.de/pdf/ibm_hitrc11.pdf
- * Keyboard Layout, Scan Code Set, POR, and Commands.
- *
- * [4] PS/2 Reference Manuals
- * http://www.mcamafia.de/pdf/ibm_hitrc07.pdf
- * Collection of IBM Personal System/2 documents.
- *
- * [5] TrackPoint Engineering Specifications for version 3E
- * https://web.archive.org/web/20100526161812/http://wwwcssrv.almaden.ibm.com/trackpoint/download.html
- */
POSSIBILITY OF SUCH DAMAGE.
*/
+/*
+ * PS/2 protocol busywait version
+ */
+
#include <stdbool.h>
#include <util/delay.h>
#include "ps2.h"
#include "debug.h"
-/*
- * PS/2 protocol busywait version
- */
-
#define WAIT(stat, us, err) do { \
if (!wait_##stat(us)) { \
ps2_error = err; \
} \
} while (0)
+
uint8_t ps2_error = PS2_ERR_NONE;
uint8_t ps2_host_send(uint8_t data)
{
- uint8_t res = 0;
bool parity = true;
ps2_error = PS2_ERR_NONE;
+
/* terminate a transmission if we have */
inhibit();
- _delay_us(200); // at least 100us
+ _delay_us(100); // 100us [4]p.13, [5]p.50
- /* start bit [1] */
+ /* 'Request to Send' and Start bit */
data_lo();
clock_hi();
- WAIT(clock_lo, 20000, 10); // may take 15ms at most until device starts clocking
- /* data [2-9] */
+ WAIT(clock_lo, 10000, 10); // 10ms [5]p.50
+
+ /* Data bit */
for (uint8_t i = 0; i < 8; i++) {
_delay_us(15);
if (data&(1<<i)) {
WAIT(clock_hi, 50, 2);
WAIT(clock_lo, 50, 3);
}
- /* parity [10] */
+
+ /* Parity bit */
_delay_us(15);
if (parity) { data_hi(); } else { data_lo(); }
WAIT(clock_hi, 50, 4);
WAIT(clock_lo, 50, 5);
- /* stop bit [11] */
+
+ /* Stop bit */
_delay_us(15);
data_hi();
- /* ack [12] */
+
+ /* Ack */
WAIT(data_lo, 50, 6);
WAIT(clock_lo, 50, 7);
WAIT(data_hi, 50, 9);
inhibit();
- res = ps2_host_recv_response();
+ return ps2_host_recv_response();
ERROR:
inhibit();
- return res;
+ return 0;
}
/* receive data when host want else inhibit communication */
uint8_t ps2_host_recv_response(void)
{
- // Command might take 20ms to response([3]p.21)
- // TrackPoint might take 25ms ([5]2.7)
+ // Command may take 25ms/20ms at most([5]p.46, [3]p.21)
// 250 * 100us(wait for start bit in ps2_host_recv)
uint8_t data = 0;
uint8_t try = 250;
return data;
}
-/* send LED state to keyboard */
-void ps2_host_set_led(uint8_t led)
-{
- ps2_host_send(0xED);
- ps2_host_send(led);
-}
-
-
/* called after start bit comes */
uint8_t ps2_host_recv(void)
{
inhibit();
return 0;
}
+
+/* send LED state to keyboard */
+void ps2_host_set_led(uint8_t led)
+{
+ ps2_host_send(0xED);
+ ps2_host_send(led);
+}
--- /dev/null
+/*
+Copyright 2010,2011,2012,2013 Jun WAKO <wakojun@gmail.com>
+
+This software is licensed with a Modified BSD License.
+All of this is supposed to be Free Software, Open Source, DFSG-free,
+GPL-compatible, and OK to use in both free and proprietary applications.
+Additions and corrections to this file are welcome.
+
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+* Redistributions of source code must retain the above copyright
+ notice, this list of conditions and the following disclaimer.
+
+* Redistributions in binary form must reproduce the above copyright
+ notice, this list of conditions and the following disclaimer in
+ the documentation and/or other materials provided with the
+ distribution.
+
+* Neither the name of the copyright holders nor the names of
+ contributors may be used to endorse or promote products derived
+ from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGE.
+*/
+
+/*
+ * PS/2 protocol Pin interrupt version
+ */
+
+#include <stdbool.h>
+#include <util/delay.h>
+#include "ps2.h"
+#include "debug.h"
+
+
+#define WAIT(stat, us, err) do { \
+ if (!wait_##stat(us)) { \
+ ps2_error = err; \
+ goto ERROR; \
+ } \
+} while (0)
+
+
+uint8_t ps2_error = PS2_ERR_NONE;
+
+
+static inline uint8_t pbuf_dequeue(void);
+static inline void pbuf_enqueue(uint8_t data);
+static inline bool pbuf_has_data(void);
+static inline void pbuf_clear(void);
+
+
+void ps2_host_init(void)
+{
+ idle();
+ PS2_INT_INIT();
+ PS2_INT_ON();
+ // POR(150-2000ms) plus BAT(300-500ms) may take 2.5sec([3]p.20)
+ //_delay_ms(2500);
+}
+
+uint8_t ps2_host_send(uint8_t data)
+{
+ bool parity = true;
+ ps2_error = PS2_ERR_NONE;
+
+ PS2_INT_OFF();
+
+ /* terminate a transmission if we have */
+ inhibit();
+ _delay_us(100); // 100us [4]p.13, [5]p.50
+
+ /* 'Request to Send' and Start bit */
+ data_lo();
+ clock_hi();
+ WAIT(clock_lo, 10000, 10); // 10ms [5]p.50
+
+ /* Data bit[2-9] */
+ for (uint8_t i = 0; i < 8; i++) {
+ _delay_us(15);
+ if (data&(1<<i)) {
+ parity = !parity;
+ data_hi();
+ } else {
+ data_lo();
+ }
+ WAIT(clock_hi, 50, 2);
+ WAIT(clock_lo, 50, 3);
+ }
+
+ /* Parity bit */
+ _delay_us(15);
+ if (parity) { data_hi(); } else { data_lo(); }
+ WAIT(clock_hi, 50, 4);
+ WAIT(clock_lo, 50, 5);
+
+ /* Stop bit */
+ _delay_us(15);
+ data_hi();
+
+ /* Ack */
+ WAIT(data_lo, 50, 6);
+ WAIT(clock_lo, 50, 7);
+
+ /* wait for idle state */
+ WAIT(clock_hi, 50, 8);
+ WAIT(data_hi, 50, 9);
+
+ idle();
+ PS2_INT_ON();
+ return ps2_host_recv_response();
+ERROR:
+ idle();
+ PS2_INT_ON();
+ return 0;
+}
+
+uint8_t ps2_host_recv_response(void)
+{
+ // Command may take 25ms/20ms at most([5]p.46, [3]p.21)
+ uint8_t retry = 25;
+ while (retry-- && !pbuf_has_data()) {
+ _delay_ms(1);
+ }
+ return pbuf_dequeue();
+}
+
+/* get data received by interrupt */
+uint8_t ps2_host_recv(void)
+{
+ if (pbuf_has_data()) {
+ ps2_error = PS2_ERR_NONE;
+ return pbuf_dequeue();
+ } else {
+ ps2_error = PS2_ERR_NODATA;
+ return 0;
+ }
+}
+
+ISR(PS2_INT_VECT)
+{
+ static enum {
+ INIT,
+ START,
+ BIT0, BIT1, BIT2, BIT3, BIT4, BIT5, BIT6, BIT7,
+ PARITY,
+ STOP,
+ } state = INIT;
+ static uint8_t data = 0;
+ static uint8_t parity = 1;
+
+ // TODO: abort if elapse 100us from previous interrupt
+
+ // return unless falling edge
+ if (clock_in()) {
+ goto RETURN;
+ }
+
+ state++;
+ switch (state) {
+ case START:
+ if (data_in())
+ goto ERROR;
+ break;
+ case BIT0:
+ case BIT1:
+ case BIT2:
+ case BIT3:
+ case BIT4:
+ case BIT5:
+ case BIT6:
+ case BIT7:
+ data >>= 1;
+ if (data_in()) {
+ data |= 0x80;
+ parity++;
+ }
+ break;
+ case PARITY:
+ if (data_in()) {
+ if (!(parity & 0x01))
+ goto ERROR;
+ } else {
+ if (parity & 0x01)
+ goto ERROR;
+ }
+ break;
+ case STOP:
+ if (!data_in())
+ goto ERROR;
+ pbuf_enqueue(data);
+ goto DONE;
+ break;
+ default:
+ goto ERROR;
+ }
+ goto RETURN;
+ERROR:
+ ps2_error = state;
+DONE:
+ state = INIT;
+ data = 0;
+ parity = 1;
+RETURN:
+ return;
+}
+
+/* send LED state to keyboard */
+void ps2_host_set_led(uint8_t led)
+{
+ ps2_host_send(0xED);
+ ps2_host_send(led);
+}
+
+
+/*--------------------------------------------------------------------
+ * Ring buffer to store scan codes from keyboard
+ *------------------------------------------------------------------*/
+#define PBUF_SIZE 32
+static uint8_t pbuf[PBUF_SIZE];
+static uint8_t pbuf_head = 0;
+static uint8_t pbuf_tail = 0;
+static inline void pbuf_enqueue(uint8_t data)
+{
+ uint8_t sreg = SREG;
+ cli();
+ uint8_t next = (pbuf_head + 1) % PBUF_SIZE;
+ if (next != pbuf_tail) {
+ pbuf[pbuf_head] = data;
+ pbuf_head = next;
+ } else {
+ debug("pbuf: full\n");
+ }
+ SREG = sreg;
+}
+static inline uint8_t pbuf_dequeue(void)
+{
+ uint8_t val = 0;
+
+ uint8_t sreg = SREG;
+ cli();
+ if (pbuf_head != pbuf_tail) {
+ val = pbuf[pbuf_tail];
+ pbuf_tail = (pbuf_tail + 1) % PBUF_SIZE;
+ }
+ SREG = sreg;
+
+ return val;
+}
+static inline bool pbuf_has_data(void)
+{
+ uint8_t sreg = SREG;
+ cli();
+ bool has_data = (pbuf_head != pbuf_tail);
+ SREG = sreg;
+ return has_data;
+}
+static inline void pbuf_clear(void)
+{
+ uint8_t sreg = SREG;
+ cli();
+ pbuf_head = pbuf_tail = 0;
+ SREG = sreg;
+}
+