altos/stmf0: Have fast ADC ring buffer code use wrap-around

[fw/altos] / src / stmf0 / ao_adc_fast.h

diff --git a/src/stmf0/ao_adc_fast.h b/src/stmf0/ao_adc_fast.h
index a2408d147914c3b471d3db455e50013beebb27a3..c6903e9fcccb3b1d618eb29793bf861e87d6f659 100644 (file)
--- a/src/stmf0/ao_adc_fast.h
+++ b/src/stmf0/ao_adc_fast.h
@@ -24,4 +24,63 @@ ao_adc_read(uint16_t *dest, int len);
 void
 ao_adc_init(void);
 
+/* Total ring size in samples */
+#define AO_ADC_RING_SIZE       256
+
+extern uint16_t        ao_adc_ring[AO_ADC_RING_SIZE];
+
+#define ao_adc_ring_step(pos,inc)      (((pos) + (inc)) & (AO_ADC_RING_SIZE - 1))
+
+extern uint16_t        ao_adc_ring_head, ao_adc_ring_remain;
+extern uint16_t        ao_adc_running;
+
+/*
+ * Place to start fetching values from
+ */
+static inline uint16_t
+ao_adc_ring_tail(void)
+{
+       return (ao_adc_ring_head - ao_adc_ring_remain) & (AO_ADC_RING_SIZE - 1);
+}
+
+void
+_ao_adc_start(void);
+
+/*
+ * Space available to write ADC values into
+ */
+static inline uint16_t
+_ao_adc_space(void)
+{
+       /* Free to end of buffer? */
+       if (ao_adc_ring_remain <= ao_adc_ring_head)
+               return AO_ADC_RING_SIZE - ao_adc_ring_head;
+
+       /* no, return just the unused entries beyond head */
+       return AO_ADC_RING_SIZE - ao_adc_ring_remain;
+}
+
+static inline uint16_t
+ao_adc_get(uint16_t n)
+{
+       ao_arch_block_interrupts();
+       while (ao_adc_ring_remain < n) {
+               if (!ao_adc_running)
+                       _ao_adc_start();
+               ao_sleep(&ao_adc_ring_head);
+       }
+       ao_arch_release_interrupts();
+       return ao_adc_ring_tail();
+}
+
+static inline void
+ao_adc_ack(uint16_t n)
+{
+       ao_arch_block_interrupts();
+       ao_adc_ring_remain -= n;
+       if (!ao_adc_running)
+               _ao_adc_start();
+       ao_arch_release_interrupts();
+}
+
 #endif /* _AO_ADC_FAST_H_ */