#include <stdbool.h>
#include <avr/interrupt.h>
#include <util/atomic.h>
-#include "ringbuf.h"
#include "ibmpc.h"
#include "debug.h"
#include "timer.h"
} while (0)
-#define BUF_SIZE 16
-static uint8_t buf[BUF_SIZE];
-static ringbuf_t rb = {
- .buffer = buf,
- .head = 0,
- .tail = 0,
- .size_mask = BUF_SIZE - 1
-};
-
volatile uint8_t ibmpc_protocol = IBMPC_PROTOCOL_AT;
volatile uint8_t ibmpc_error = IBMPC_ERR_NONE;
+/* 2-byte buffer for data received from keyhboard
+ * buffer states:
+ * FFFF: empty
+ * FFss: one data
+ * sstt: two data(full)
+ * 0xFF can not be stored as data in buffer because it means empty or no data.
+ */
+static volatile uint16_t recv_data = 0xFFFF;
+/* internal state of receiving data */
+static volatile uint16_t isr_data = 0x8000;
+
void ibmpc_host_init(void)
{
- // initialize reset pin
- IBMPC_RST_PORT |= (1<<IBMPC_RST_BIT1);
- IBMPC_RST_DDR |= (1<<IBMPC_RST_BIT1);
- IBMPC_RST_PORT |= (1<<IBMPC_RST_BIT2);
- IBMPC_RST_DDR |= (1<<IBMPC_RST_BIT2);
+ // initialize reset pin to HiZ
+ IBMPC_RST_HIZ();
inhibit();
IBMPC_INT_INIT();
IBMPC_INT_OFF();
WAIT(data_hi, 50, 9);
// clear buffer to get response correctly
- ringbuf_reset(&rb);
+ recv_data = 0xFFFF;
ibmpc_host_isr_clear();
idle();
}
/*
- * Receive data from keyboard with ISR
+ * Receive data from keyboard
*/
-static volatile int16_t recv_data = -1;
-static volatile uint16_t isr_data = 0x8000;
-
-void ibmpc_host_isr_clear(void)
-{
- isr_data = 0x8000;
-}
-
int16_t ibmpc_host_recv(void)
{
- int16_t data = 0;
+ uint16_t data = 0;
+ uint8_t ret = 0xFF;
+
ATOMIC_BLOCK(ATOMIC_RESTORESTATE) {
data = recv_data;
- recv_data = -1;
+ if ((data&0xFF00) != 0xFF00) { // recv_data:sstt -> recv_data:FFtt, ret:ss
+ ret = (data>>8)&0x00FF;
+ recv_data = data | 0xFF00;
+ } else if (data != 0xFFFF) { // recv_data:FFss -> recv_data:FFFF, ret:ss
+ ret = data&0x00FF;
+ recv_data = data | 0x00FF;
+ }
}
- if (data != -1) {
- dprintf("r%04X ", data);
+
+ if (ret != 0xFF) {
+ dprintf("r%02X(%04X) ", ret, recv_data);
}
- return data;
+ return ((ret != 0xFF) ? ret : -1);
}
return data;
}
+void ibmpc_host_isr_clear(void)
+{
+ isr_data = 0x8000;
+ recv_data = 0xFFFF;
+}
+
+// NOTE: With this ISR data line can be read within 2us after clock falling edge.
+// To read data line early as possible:
+// write naked ISR with asembly code to read the line and call C func to do other job?
ISR(IBMPC_INT_VECT)
{
uint8_t dbit;
isr_data = isr_data>>1;
if (dbit) isr_data |= 0x8000;
- // isr_data:
+ // isr_data: state of receiving data from keyboard
// 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
// -----------------------------------------------------
// Initial: *1 0 0 0 0 0 0 0 | 0 0 0 0 0 0 0 0
break;
case 0b11000000:
// XT Clone-done
- recv_data = (isr_data>>8) & 0xFF;
+ recv_data = recv_data<<8;
+ recv_data |= (isr_data>>8) & 0xFF;
goto DONE;
break;
case 0b10100000:
- // XT IBM-done or AT-midway
- // wait and check for clock of AT stop bit
- if (wait_clock_hi(100) && wait_clock_lo(100)) { // FIXME this makes ISR prologe long
- // AT-midway
- return;
- } else {
- // XT-IBM-done
- recv_data = (isr_data>>8) & 0xFF;
- goto DONE;
- }
+ {
+ uint8_t us = 150;
+ // wait for rising and falling edge of AT stop bit
+ while (!(IBMPC_CLOCK_PIN&(1<<IBMPC_CLOCK_BIT)) && us) { wait_us(1); us--; }
+ while ( IBMPC_CLOCK_PIN&(1<<IBMPC_CLOCK_BIT) && us) { wait_us(1); us--; }
+
+ if (us) {
+ // found stop bit: return immediately and process the stop bit in ISR
+ // AT-midway
+ return;
+ } else {
+ // no stop bit
+ // XT-IBM-done
+ recv_data = recv_data<<8;
+ recv_data |= (isr_data>>8) & 0xFF;
+ goto DONE;
+ }
+ }
break;
case 0b00010000:
case 0b10010000:
case 0b01010000:
case 0b11010000:
// AT-done
- recv_data = (isr_data>>6) & 0xFF;
+ recv_data = recv_data<<8;
+ recv_data |= (isr_data>>6) & 0xFF;
goto DONE;
break;
case 0b01100000:
break;
}
DONE:
- // TODO: buffer for recv_data
+ // TODO: check protocol change to support keyboard howswap
+ // not correct if there is clock edge within short time like 100us after receving data
+ // TODO: process error code: 0x00(AT), 0xFF(XT) in particular
isr_data = 0x8000; // clear to next data
return;
}