altos/drivers: Use spi duplex to fetch register values

We read register values during regular operation, so let's improve
performance a bit by making this faster.

Signed-off-by: Keith Packard <keithp@keithp.com>

diff --git a/src/drivers/ao_cc1200.c b/src/drivers/ao_cc1200.c
index 799f808fc0105b69d9acbcdcd951758c252f6f36..b295d054096bcf6c299486d2814e8cde39d5a9b2 100644 (file)
--- a/src/drivers/ao_cc1200.c
+++ b/src/drivers/ao_cc1200.c
@@ -65,7 +65,7 @@ extern const uint32_t ao_radio_cal;
 static uint8_t
 ao_radio_reg_read(uint16_t addr)
 {
-       uint8_t data[2];
+       uint8_t data[3];
        uint8_t d;
 
 #if CC1200_TRACE
@@ -84,13 +84,12 @@ ao_radio_reg_read(uint16_t addr)
                d = 1;
        }
        ao_radio_select();
-       ao_radio_spi_send(data, d);
-       ao_radio_spi_recv(data, 1);
+       ao_radio_duplex(data, data, d + 1);
        ao_radio_deselect();
 #if CC1200_TRACE
-       printf (" %02x\n", data[0]);
+       printf (" %02x\n", data[d]);
 #endif
-       return data[0];
+       return data[d];
 }
 
 static void