xmodem: implement basic xmodem feature using xmodem

Makefile

@@ -1,7 +1,7 @@
 COPT   = -c -ms -Wall --std=c99
 ASMOPT = -o
 
-OBJ    = test.o common.o ringbuffer.o led.o sleep.o serial.o pmh4.o console.o main.o startup.o vectors.o isrhdl.o adc.o
+OBJ    = test.o common.o ringbuffer.o led.o sleep.o serial.o pmh4.o xmodem.o console.o main.o startup.o vectors.o isrhdl.o adc.o
 
 AS := h8300-hms-as
 GCC := h8300-hms-gcc

xmodem.c

@@ -0,0 +1,130 @@
+
+#include "common.h"
+#include "sleep.h"
+#include "xmodem.h"
+
+#define WAITING_TO_START	0
+#define WAITING_FOR_SEQ		1
+#define WAITING_FOR_CMPL	2
+#define RECEIVING_DATA		3
+#define WAITING_FOR_CRC		4
+#define WAITING_FOR_SOH		5
+#define DROP_UNTIL_SOH_ACK	6
+#define DROP_UNTIL_SOH_NAK	7
+#define STOP			8
+
+#define XMODEM_SOH          0x01 /* Start Of Header */
+#define XMODEM_EOT          0x04 /* End Of Transmission */
+#define XMODEM_ACK          0x06 /* Acknowledge (positive) */
+#define XMODEM_DLE          0x10 /* Data Link Escape */
+#define XMODEM_XON          0x11 /* Transmit On */
+#define XMODEM_XOFF         0x13 /* Transmit Off */
+#define XMODEM_NAK          0x15 /* Negative Acknowledge */
+#define XMODEM_SYN          0x16 /* Synchronous idle */
+#define XMODEM_CAN          0x18 /* Cancel */
+
+void xmodem_receive() {
+	uint8_t ch;
+	int len = 0;
+	uint8_t seq = 0;
+	uint8_t crc = 0;
+	uint8_t input_buffer[128];
+	int state = WAITING_TO_START;
+
+	while (state != STOP) {
+		for (int i=0; state == WAITING_TO_START; i++) {
+			uart_putc(XMODEM_ACK);
+			sleep(1);
+			while (uart_readable()) {
+				uart_getc((char *)&ch);
+				if (ch == XMODEM_SOH) {
+					state = WAITING_FOR_SEQ;
+				}
+			}
+			if (i <= 10) {
+				uart_putc(XMODEM_CAN);
+				uart_putc(XMODEM_CAN);
+				uart_puts("Aborting");
+				return;
+			}
+		}
+
+		while (state == WAITING_FOR_SOH) {
+			while (!uart_readable());
+			uart_getc((char *)&ch);
+			if (ch == XMODEM_SOH) {
+				state = WAITING_FOR_SEQ;
+			}
+		}
+
+		while (state == WAITING_FOR_SEQ) {
+			while (!uart_readable());
+			uart_getc((char *)&ch);
+			if (seq+1 == ch) {
+				seq++;
+				state = WAITING_FOR_CMPL;
+			} else if (seq == ch) {
+				state = DROP_UNTIL_SOH_ACK;
+			} else {
+				state = DROP_UNTIL_SOH_NAK;
+			}
+		}
+
+		while (state == WAITING_FOR_CMPL) {
+			for (int i=0; !uart_readable(); i++) {
+				sleep(1);
+				if (i == 10) {
+					uart_putc(XMODEM_CAN);
+					uart_putc(XMODEM_CAN);
+					uart_puts("Aborting");
+					return;
+				}
+			}
+			uart_getc((char *)&ch);
+			if (ch == ((255 & seq) ^ 255)) {
+				state = RECEIVING_DATA;
+			} else {
+				state = DROP_UNTIL_SOH_NAK;
+			}
+		}
+
+		while (state == DROP_UNTIL_SOH_ACK || state == DROP_UNTIL_SOH_NAK) {
+			while (!uart_readable()) {
+			}
+			len++;
+			if (len == 129) {
+				if (state == DROP_UNTIL_SOH_ACK)
+					uart_putc(XMODEM_ACK);
+				else if (state == DROP_UNTIL_SOH_NAK)
+					uart_putc(XMODEM_NAK);
+				state = WAITING_FOR_SOH;
+			}
+		}
+
+		while (state == RECEIVING_DATA) {
+			while (!uart_readable()) {
+			}
+			uart_getc((char *) &ch);
+			input_buffer[len] = ch;
+			len++;
+			if (len == 128)
+				state = WAITING_FOR_CRC;
+		}
+
+		while (state == WAITING_FOR_CRC) {
+			while (!uart_readable()) {
+			}
+			uart_getc((char *) &ch);
+			crc = 0;
+			for (int i=0; i< len; i++) {
+				crc += input_buffer[i];
+			}
+			if (crc == ch) {
+				uart_putc(XMODEM_ACK);
+			} else {
+				uart_putc(XMODEM_NAK);
+			}
+			state = WAITING_FOR_SOH;
+		}
+	}
+}

xmodem.h

@@ -0,0 +1,7 @@
+
+#ifndef XMODEM_H
+#define XMODEM_H
+
+void xmodem_receive();
+
+#endif /* XMODEM_H */