From b038c3b87564e9f4acac0019b18fd6d20692ac38 Mon Sep 17 00:00:00 2001
From: Joe Zhao <ztuowen@gmail.com>
Date: Fri, 16 May 2014 16:41:30 +0800
Subject: Tangential change

---
 rs422lib/rsbus.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

(limited to 'rs422lib/rsbus.c')

diff --git a/rs422lib/rsbus.c b/rs422lib/rsbus.c
index 4c0fcb2..2b548a6 100644
--- a/rs422lib/rsbus.c
+++ b/rs422lib/rsbus.c
@@ -10,6 +10,11 @@
 #define SYSRET (0xF0)
 #define INSREP (0x0F)
 
+// Maximum size of receive buffer
+#define RSMAX (20)
+
+#define CODE_LEN (6)
+
 unsigned char rs_rxbuf[RSMAX];
 unsigned char len;
 unsigned char pch;
@@ -17,7 +22,7 @@ rshdlr rxhdlr;
 enum rs_stat{REST,ST,ADDR,READ,DISCARD,ED,DED};
 enum rs_stat rs_st=REST;
 
-unsigned char rs_tx[20]={STBIT1,0,RSADDR,MACTYPE};
+unsigned char rs_tx[CODE_LEN+RS_MAX]={STBIT1,0,RSADDR,MACTYPE};
 volatile unsigned char tx_len;
 volatile unsigned char tx_pos=255;
 
@@ -36,6 +41,7 @@ __interrupt void USCI0TX_ISR(void)
    	   UCA0TXBUF = rs_tx[tx_pos++]; // TX next character
 }
 
+// Inline send for ISR
 #pragma FUNC_ALWAYS_INLINE(rsbus_w_irq)
 static __inline void rsbus_w_irq(unsigned char* buf,unsigned int len)
 {
@@ -46,8 +52,6 @@ static __inline void rsbus_w_irq(unsigned char* buf,unsigned int len)
 	tx_len=len+7;
 	unsigned int parity=MACTYPE^RSADDR;
 	rs_tx[1]=0; // Useless addr spec
-	rs_tx[2]=RSADDR;
-	rs_tx[3]=MACTYPE;
 	for (i=0;i<len;++i)
 		parity^=(rs_tx[4+i]=buf[i]);
 	rs_tx[4+len]=parity;
@@ -132,19 +136,19 @@ __interrupt void rsbus_rx(void)
 	}
 }
 
+// Send something to the rs422 bus
+// Length must not exceeds RS_MAX
 void rsbus_w(int addr,unsigned char* buf,unsigned int len)
 {
 	while (tx_pos < tx_len)		// This shouldn't happen
 		__delay_cycles(100);	// Race condition -> wait
 	unsigned int i;
-	if (len>14)
+	if (len>RS_MAX)
 		return;
 	RSOUT |= RSPIN;
 	tx_len=len+7;
 	unsigned int parity=addr^MACTYPE^RSADDR;
 	rs_tx[1]=addr; // Useless addr spec
-	rs_tx[2]=RSADDR;
-	rs_tx[3]=MACTYPE;
 	for (i=0;i<len;++i)
 		parity^=(rs_tx[4+i]=buf[i]);
 	rs_tx[4+len]=parity;
-- 
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