The base address determines a peripherals id, which identifies its
interrupt line, see NRF51 reference manual section 10 peripheral
interface. This little gem calculates the peripheral id based
on its base address.

Signed-off-by: Steffen Görtz <cont...@steffen-goertz.de>
---
 hw/arm/nrf51_soc.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/hw/arm/nrf51_soc.c b/hw/arm/nrf51_soc.c
index 9f9649c780..441d05e1ef 100644
--- a/hw/arm/nrf51_soc.c
+++ b/hw/arm/nrf51_soc.c
@@ -38,6 +38,9 @@
 #define NRF51822_FLASH_SIZE     (256 * 1024)
 #define NRF51822_SRAM_SIZE      (16 * 1024)
 
+/* IRQ lines can be derived from peripheral base addresses */
+#define BASE_TO_IRQ(base) (((base) >> 12) & 0x1F)
+
 static void nrf51_soc_realize(DeviceState *dev_soc, Error **errp)
 {
     NRF51State *s = NRF51_SOC(dev_soc);
-- 
2.18.0


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