From: Bernard Blackham <dagobah@ucc.asn.au>
Date: Sun, 10 Aug 2003 07:45:58 +0000 (+0000)
Subject: Start of coin mech handler
X-Git-Tag: ROMW~87
X-Git-Url: https://git.ucc.asn.au/?a=commitdiff_plain;h=65f351eccb34b310c15e3cd38dcae5b152187092;p=uccvend-snackrom.git

Start of coin mech handler
---

diff --git a/ROM2/coinmech.c b/ROM2/coinmech.c
index 80a11a7..a5a38e0 100644
--- a/ROM2/coinmech.c
+++ b/ROM2/coinmech.c
@@ -1,2 +1,78 @@
 #include "vend.h"
 
+#define COINMECH_ID   0x20
+
+u8 last_byte;
+
+
+u8 parity_test(u8 c) {
+	u8 parity = 0;
+	for (parity = 0; c; c = c>>1) {
+		if (c&1) parity = !parity;
+	}
+	return parity;
+}
+
+/*
+ * parity_good truth table:
+ *
+ *      | parity_test(c)
+ *      | 0   1
+ * -----+---------
+ * R8 0 | 1   0
+ *    1 | 0   1
+ */
+
+bool parity_good(u8 c) {
+	u8 R8 = (_io_ports[M6811_SCCR1] & M6811_R8)?1:0;
+	u8 p = parity_test(c)?1:0;
+	return R8 == p;
+}
+
+void send_byte(u8 c) {
+	last_byte = c;
+	while (!(_io_ports[M6811_SCSR] & M6811_TDRE)); /* wait for TD register empty */
+
+	if (parity_of(c))
+		bset(&_io_ports[M6811_SCCR1], M6811_T8);
+	else
+		bclr(&_io_ports[M6811_SCCR1], M6811_T8);
+}
+
+void ask_for_retrans() {
+	/* sends an 0xff down the line */
+	send_byte(0xff);
+}
+
+
+u8 packet_pos = 0;
+
+#define IS_CTRL(x) (x & 0x10) /* true if this packet is a control packet */
+void sci_interrupt() {
+	u8 in;
+	in = _io_ports[M6811_SCDR];
+	
+	/* test for framing errors & parity bit */
+	if (_io_ports[M6811_SCSR] & M6811_FE || !parity_good(in)) {
+		_io_ports[M6811_SCDR]; /* read of register req'd to clear FE */
+		ask_for_retrans();
+		return;
+	}
+
+	/* all bytes must have the correct ID in the 3 MSBs */
+	if (in & 0xe0 != COINMECH_ID) return;
+
+	/* we have a good packet */
+	if (in == 0x3f) {
+		/* retransmit was requested */
+		send_byte(last_byte);
+		return;
+	}
+
+	if (packet_pos != 0 && !IS_CTRL(x&0x10)) {
+		switch (in & 0x0f) {
+		}
+	} else {
+
+	}
+}