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   1 /*
   2  * Copyright © 2015 Keith Packard <keithp@keithp.com>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; version 2 of the License.
   7  *
   8  * This program is distributed in the hope that it will be useful, but
   9  * WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along
  14  * with this program; if not, write to the Free Software Foundation, Inc.,
  15  * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
  16  */
  17
  18 #ifndef _AO_ADC_FAST_H_
  19 #define _AO_ADC_FAST_H_
  20
  21 void
  22 ao_adc_read(uint16_t *dest, int len);
  23
  24 void
  25 ao_adc_init(void);
  26
  27 /* Total ring size in samples */
  28 #define AO_ADC_RING_SIZE        256
  29 /* Number of samples fetched per ao_adc_start call */
  30 #define AO_ADC_RING_CHUNK       (AO_ADC_RING_SIZE >> 1)
  31
  32 extern uint16_t ao_adc_ring[AO_ADC_RING_SIZE];
  33
  34 #define ao_adc_ring_step(pos,inc)       (((pos) + (inc)) & (AO_ADC_RING_SIZE - 1))
  35
  36 extern uint16_t ao_adc_ring_head, ao_adc_ring_tail;
  37 extern uint8_t  ao_adc_running;
  38
  39 void
  40 _ao_adc_start(void);
  41
  42 static inline uint16_t
  43 _ao_adc_remain(void)
  44 {
  45         if (ao_adc_ring_tail > ao_adc_ring_head)
  46                 return AO_ADC_RING_SIZE - ao_adc_ring_tail;
  47         return ao_adc_ring_head - ao_adc_ring_tail;
  48 }
  49
  50 static inline uint16_t
  51 _ao_adc_space(void)
  52 {
  53         if (ao_adc_ring_head == ao_adc_ring_tail)
  54                 return AO_ADC_RING_SIZE;
  55         if (ao_adc_ring_head > ao_adc_ring_tail)
  56                 return AO_ADC_RING_SIZE - ao_adc_ring_head;
  57         return ao_adc_ring_tail - ao_adc_ring_head;
  58 }
  59
  60 static inline uint16_t *
  61 ao_adc_get(uint16_t n)
  62 {
  63         if (ao_adc_ring_tail + n > AO_ADC_RING_SIZE)
  64                 ao_panic(AO_PANIC_ADC);
  65         ao_arch_block_interrupts();
  66         while (_ao_adc_remain() < n) {
  67                 if (!ao_adc_running)
  68                         _ao_adc_start();
  69                 ao_sleep(&ao_adc_ring_head);
  70         }
  71         ao_arch_release_interrupts();
  72         return &ao_adc_ring[ao_adc_ring_tail];
  73 }
  74
  75 static inline void
  76 ao_adc_ack(uint16_t n)
  77 {
  78         if (ao_adc_ring_tail + n > AO_ADC_RING_SIZE)
  79                 ao_panic(AO_PANIC_ADC);
  80         ao_arch_block_interrupts();
  81         ao_adc_ring_tail += n;
  82         if (ao_adc_ring_tail == AO_ADC_RING_SIZE)
  83                 ao_adc_ring_tail = 0;
  84         if (!ao_adc_running && _ao_adc_space() >= AO_ADC_RING_CHUNK)
  85                 _ao_adc_start();
  86         ao_arch_release_interrupts();
  87 }
  88
  89 #endif /* _AO_ADC_FAST_H_ */