rc_servos: revert use of registers for global variables

[protos/rc_servos.git] / main.c

diff --git a/main.c b/main.c
index 657e54d..d390554 100644 (file)
--- a/main.c
+++ b/main.c
@@ -21,10 +21,13 @@ static struct servo servo_table[] = {
 };
 #define NB_SERVO (sizeof(servo_table)/sizeof(*servo_table))
 
-register uint8_t bypass asm("r2");
-register uint8_t done asm("r3");
-register uint8_t portval asm("r4");
-register uint8_t rxidx asm("r5");
+static volatile uint8_t bypass;
+static volatile uint8_t done;
+static volatile uint8_t portval;
+static volatile uint8_t rxidx;
+
+#define BYPASS_ENABLE 14
+#define BYPASS_DISABLE 15
 
 /*
  * SPI protocol:
@@ -37,22 +40,22 @@ register uint8_t rxidx asm("r5");
  * Command 14 is to enable bypass mode.
  * Command 15 is to disable bypass mode.
  */
-register union {
+static volatile union {
        uint8_t u8;
        struct {
-               uint16_t zero:1;
-               uint16_t cmd_num:4;
-               uint16_t val_msb:3;
+               uint8_t zero:1;
+               uint8_t cmd_num:4;
+               uint8_t val_msb:3;
        };
-} byte0 asm("r6");
+} byte0;
 
-register union {
+static volatile union {
        uint8_t u8;
        struct {
                uint8_t one:1;
                uint8_t val_lsb:7;
        };
-} byte1 asm("r7");
+} byte1;
 
 SIGNAL(TIMER1_COMPA_vect)
 {
@@ -94,10 +97,10 @@ static void poll_spi(void)
                        val += byte1.val_lsb;
                        servo_table[byte0.cmd_num].command = val;
                }
-               else if (byte0.cmd_num == 14) {
+               else if (byte0.cmd_num == BYPASS_ENABLE) {
                        bypass = 1;
                }
-               else if (byte0.cmd_num == 15) {
+               else if (byte0.cmd_num == BYPASS_DISABLE) {
                        bypass = 0;
                }
        }
@@ -157,6 +160,7 @@ int main(void)
 
        sei();
 
+       bypass = 0;
        while (1) {
                t = TCNT0;
                for (i = 0; i < NB_SERVO; i++) {