*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; version 2 of the License.
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
/* Total ring size in samples */
#define AO_ADC_RING_SIZE 256
-/* Number of samples fetched per ao_adc_start call */
-#define AO_ADC_RING_CHUNK (AO_ADC_RING_SIZE >> 1)
-extern uint16_t ao_adc_ring[AO_ADC_RING_SIZE];
+extern uint16_t ao_adc_ring[AO_ADC_RING_SIZE] __attribute__((aligned(4)));
#define ao_adc_ring_step(pos,inc) (((pos) + (inc)) & (AO_ADC_RING_SIZE - 1))
-extern uint16_t ao_adc_ring_head, ao_adc_ring_tail;
-extern uint8_t ao_adc_running;
-
-void
-_ao_adc_start(void);
+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_remain(void)
+ao_adc_ring_tail(void)
{
- if (ao_adc_ring_tail > ao_adc_ring_head)
- return AO_ADC_RING_SIZE - ao_adc_ring_tail;
- return ao_adc_ring_head - ao_adc_ring_tail;
+ 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)
{
- if (ao_adc_ring_head == ao_adc_ring_tail)
- return AO_ADC_RING_SIZE;
- if (ao_adc_ring_head > ao_adc_ring_tail)
+ /* Free to end of buffer? */
+ if (ao_adc_ring_remain <= ao_adc_ring_head)
return AO_ADC_RING_SIZE - ao_adc_ring_head;
- return ao_adc_ring_tail - 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 *
+static inline uint16_t
ao_adc_get(uint16_t n)
{
- if (ao_adc_ring_tail + n > AO_ADC_RING_SIZE)
- ao_panic(AO_PANIC_ADC);
ao_arch_block_interrupts();
- while (_ao_adc_remain() < n) {
+ 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[ao_adc_ring_tail];
+ return ao_adc_ring_tail();
}
static inline void
ao_adc_ack(uint16_t n)
{
- if (ao_adc_ring_tail + n > AO_ADC_RING_SIZE)
- ao_panic(AO_PANIC_ADC);
ao_arch_block_interrupts();
- ao_adc_ring_tail += n;
- if (ao_adc_ring_tail == AO_ADC_RING_SIZE)
- ao_adc_ring_tail = 0;
- if (!ao_adc_running && _ao_adc_space() >= AO_ADC_RING_CHUNK)
+ ao_adc_ring_remain -= n;
+ if (!ao_adc_running)
_ao_adc_start();
ao_arch_release_interrupts();
}