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71 lines
1.1 KiB
71 lines
1.1 KiB
9 years ago
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#include <stdint.h>
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#include <malloc.h>
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#include "meanbuf.h"
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#include "malloc_safe.h"
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struct meanbuf_struct {
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float * buf; // buffer (allocated at init)
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size_t cap; // capacity
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size_t nw; // next write index
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float mean; // updated on write
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};
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/** Init a buffer */
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MeanBuf *meanbuf_create(size_t size)
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{
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MeanBuf *mb = malloc_s(sizeof(MeanBuf));
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if (size < 1) size = 1;
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mb->buf = calloc_s(size, sizeof(float)); // calloc, so it starts with zeros.
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mb->cap = size;
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mb->nw = 0;
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mb->mean = 0;
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// clean buffer
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for (uint16_t i = 0; i < size; i++) {
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mb->buf[i] = 0;
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}
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return mb;
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}
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void meanbuf_destroy(MeanBuf *mb)
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{
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if (mb == NULL) return;
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if (mb->buf != NULL) {
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free(mb->buf);
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}
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free(mb);
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}
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/** Add a value to the buffer. Returns current mean. */
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float meanbuf_add(MeanBuf *mb, float f)
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{
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// add sample
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mb->buf[mb->nw++] = f;
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if (mb->nw == mb->cap) mb->nw = 0;
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// calculate average
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float acc = 0;
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for (size_t i = 0; i < mb->cap; i++) {
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acc += mb->buf[i];
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}
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acc /= mb->cap;
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return mb->mean = acc;
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}
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float meanbuf_current(MeanBuf *mb)
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{
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return mb->mean;
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}
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