+
+/* Check port settings for clock and data line */
+#if !(defined(PS2_CLOCK_PORT) && \
+ defined(PS2_CLOCK_PIN) && \
+ defined(PS2_CLOCK_DDR) && \
+ defined(PS2_CLOCK_BIT))
+# error "PS/2 clock port setting is required in config.h"
+#endif
+
+#if !(defined(PS2_DATA_PORT) && \
+ defined(PS2_DATA_PIN) && \
+ defined(PS2_DATA_DDR) && \
+ defined(PS2_DATA_BIT))
+# error "PS/2 data port setting is required in config.h"
+#endif
+
+/*--------------------------------------------------------------------
+ * static functions
+ *------------------------------------------------------------------*/
+static inline void clock_lo(void)
+{
+ PS2_CLOCK_PORT &= ~(1<<PS2_CLOCK_BIT);
+ PS2_CLOCK_DDR |= (1<<PS2_CLOCK_BIT);
+}
+static inline void clock_hi(void)
+{
+ /* input with pull up */
+ PS2_CLOCK_DDR &= ~(1<<PS2_CLOCK_BIT);
+ PS2_CLOCK_PORT |= (1<<PS2_CLOCK_BIT);
+}
+static inline bool clock_in(void)
+{
+ 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(void)
+{
+ PS2_DATA_PORT &= ~(1<<PS2_DATA_BIT);
+ PS2_DATA_DDR |= (1<<PS2_DATA_BIT);
+}
+static inline void data_hi(void)
+{
+ /* input with pull up */
+ PS2_DATA_DDR &= ~(1<<PS2_DATA_BIT);
+ PS2_DATA_PORT |= (1<<PS2_DATA_BIT);
+}
+static inline bool data_in(void)
+{
+ 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();
+}