1 files changed, 122 insertions, 0 deletions
diff --git a/old/ft232r/soft_uart.c b/old/ft232r/soft_uart.c
new file mode 100644
index 0000000..7993036
--- /dev/null
+++ b/old/ft232r/soft_uart.c
@@ -0,0 +1,122 @@
+
+#include <stdint.h>
+#include <stdio.h>
+#include <sys/types.h>
+
+#include "soft_uart.h"
+
+static inline uint32_t samples_per_etu(struct suart_data *su)
+{
+	return su->samplerate / su->recip_etu;
+}
+
+static const char *state_strings[] = {
+	[WAIT_RESET]		= "WAIT_RESET",
+	[IN_RESET]		= "IN_RESET",
+	[WAIT_START_FALLEDGE]	= "WAIT_START_FALLEDGE",
+	[WAIT_START_ETU07]	= "WAIT_START_ETU07",
+	[RX_BITS]		= "RX_BITS",
+	[POST_RX_WAIT_HIGH]	= "POST_RX_WAIT_HIGH",
+};
+
+static void change_state(struct suart_data *su, enum suart_state new_state)
+{
+	printf("State change: %s -> %s\n", state_strings[su->state], state_strings[new_state]);
+	su->state = new_state;
+}
+
+/* According to ISO/IEC 7816-3 Section 6.1.2 */
+int suart_process_sample_bit(struct suart_data *suart, uint8_t clk_bit, uint8_t rst_bit, uint8_t sample_bit)
+{
+	uint32_t samp_per_etu = samples_per_etu(suart);
+	uint8_t next_bit;
+
+	if (rst_bit == 0 && suart->state != IN_RESET) {
+		change_state(suart, IN_RESET);
+		/* FIXME: reset some other things? */
+	}
+
+	switch (suart->state) {
+	case WAIT_RESET:
+		if (rst_bit == 0)
+			change_state(suart, IN_RESET);
+		break;
+	case IN_RESET:
+		if (rst_bit == 1)
+			change_state(suart, WAIT_START_FALLEDGE);
+		break;
+	case WAIT_START_FALLEDGE:
+		if (sample_bit == 0) {
+			suart->sample_after_sbit = 0;
+			suart->bits_pending = suart->num_bits + 1;
+			change_state(suart, WAIT_START_ETU07);
+		}
+		break;
+	case WAIT_START_ETU07:
+		if (suart->sample_after_sbit > (samp_per_etu/2)+1) {
+			if (sample_bit != 0) {
+				printf("!!!!!!!!!!!!!!!!!!!!! start bit after 0.7 * ETU no longer low\n");
+			} else {
+				change_state(suart, RX_BITS);
+				suart->rx_char = 0;
+			}
+		}
+		/* else stay in this state until the condition is true */
+		break;
+	case RX_BITS:
+		next_bit = suart->num_bits+1 - suart->bits_pending;
+#if 0
+		printf("\tRX_BITS: IO = %u, next_bit = %u, sample_after_sbit = %u, samp_per_etu = %u, required_after_sbit = %u\n",
+			sample_bit, next_bit, suart->sample_after_sbit, samp_per_etu,
+			(samp_per_etu/2) + ((next_bit+1) * samp_per_etu));
+#endif
+		if (suart->sample_after_sbit > (samp_per_etu/2) + ((next_bit+1) * samp_per_etu)) {
+			/* check if this is the parity bit */
+			//printf("new_bit = %u\n", sample_bit);
+			if (next_bit == suart->num_bits) {
+				/* FIXME calculate parity */
+			} else {
+				/* an actual data bit */
+				/* Section 6.1.4.1 */
+				if (suart->convention == INVERSE_CONVENTION) {
+					if (sample_bit == 1)
+						sample_bit = 0x00;
+					else
+						sample_bit = 0x80;	
+					/* shift existing patter one to the right */
+					suart->rx_char = suart->rx_char >> 1;
+					/* mask in the additional bit */
+					suart->rx_char |= sample_bit;
+				} else {
+					suart->rx_char |= (sample_bit << next_bit);
+				}
+			}
+			suart->bits_pending--;
+		}
+
+		if (suart->bits_pending == 0) {
+
+			/* output the character that we decoded */
+			printf("Output Byte: %02x\n", suart->rx_char);
+
+			change_state(suart, POST_RX_WAIT_HIGH);
+		}
+		break;
+	case POST_RX_WAIT_HIGH:
+		if (sample_bit == 0x01) {
+			/* return to initial state */
+			change_state(suart, WAIT_START_FALLEDGE);
+		}
+		break;
+	}
+	suart->sample_after_sbit++;
+}
+
+void suart_init(struct suart_data *su)
+{
+	su->state = WAIT_RESET;
+	su->convention = DIRECT_CONVENTION;
+	printf("Samplerate = %u\n", su->samplerate);
+	printf("etu = 1 / %u\n", su->recip_etu);
+	printf("samp_per_etu = %u\n", samples_per_etu(su));
+}