Diff: WAV_Reader.cpp

Revision:

1:c1046d91bff7

Child:

2:18fdd269b401

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/WAV_Reader.cpp	Fri Feb 24 15:18:01 2017 +0000
@@ -0,0 +1,191 @@
+/*
+ * WAV_Reader.cpp
+ *
+ *  Created on: 23 Feb 2017
+ *      Author: ML15AAF
+ */
+
+#include <WAV_Reader.h>
+
+WAV_Reader::Config::Config() {
+    format_tag = 0;
+    channels = 0;
+    samples_per_sec = 0;
+    avg_bytes_per_sec = 0;
+    block_align = 0;
+    bits_per_sample = 0;
+    data_pos = 0;
+    data_length = 0;
+    file_size = 0;
+}
+
+WAV_Reader::WAV_Reader() :
+        fpp(NULL), _current_pos(0), _loop(false) {
+
+}
+
+int WAV_Reader::open(FILE **filepp) {
+    int success = 0;
+
+    fpp = filepp;
+
+    if (*filepp != NULL) {
+        if (check_bytes(*fpp, "RIFF", 4)) {
+            if (check_bytes(*fpp, "WAVE", 4, 8)) {
+                config.file_size = read_num(*fpp, 4, 4);
+
+                int chunk_pos = find_chunk(*fpp, "fmt ", config.file_size, 12);
+
+                if (chunk_pos != -1) {
+                    config.format_tag = read_num(*fpp, 2, chunk_pos + 8);
+                    config.channels = read_num(*fpp, 2, chunk_pos + 10);
+                    config.samples_per_sec = read_num(*fpp, 4, chunk_pos + 12);
+                    config.avg_bytes_per_sec = read_num(*fpp, 4, chunk_pos + 16);
+                    config.block_align = read_num(*fpp, 2, chunk_pos + 20);
+                    config.bits_per_sample = read_num(*fpp, 2, chunk_pos + 22);
+                } else success = WAV_READER_FO_NO_FMT;
+
+                chunk_pos = find_chunk(*fpp, "data", config.file_size, 12);
+
+                if (chunk_pos != -1) {
+                    config.data_length = read_num(*fpp, 4, chunk_pos + 4);
+                    config.data_pos = chunk_pos + 8;
+                    reset();
+
+                } else success = success + WAV_READER_FO_NO_DATA;
+
+                if (success == 0) success = config.data_length;
+
+            } else success = WAV_READER_FO_NOT_WAV;
+        } else success = WAV_READER_FO_NOT_RIFF;
+    } else success = WAV_READER_FO_NULL_PTR;
+
+
+
+    return success;
+}
+
+int WAV_Reader::read(char buff[], int len) {
+    int data_left = config.data_length - _current_pos;
+    int to_read = len;
+
+    if (to_read > data_left) {
+        if (data_left == 0 && _loop) {
+            reset();
+        } else {
+            to_read = data_left;
+        }
+    }
+
+    size_t ret = fread(buff, 1, to_read, *fpp);
+    move_read_position(ret, _current_pos);
+
+    to_read = len - ret;
+    if (to_read > 0 && _loop) {
+        ret += read(buff + ret, to_read);
+    }
+
+    return ret;
+}
+
+void WAV_Reader::reset() {
+    seek(0, 0);
+}
+
+bool WAV_Reader::loop() {
+    return _loop;
+}
+
+void WAV_Reader::loop(bool enable) {
+    _loop = enable;
+}
+
+void WAV_Reader::seek(int num, int start) {
+    if (start < 0) start = _current_pos;
+    move_read_position(num, start);
+    fseek(*fpp, _current_pos + config.data_pos, SEEK_SET);
+}
+
+uint16_t WAV_Reader::channels() {
+    return config.channels;
+}
+
+uint32_t WAV_Reader::samples_per_sec() {
+    return config.samples_per_sec;
+}
+
+uint16_t WAV_Reader::block_align() {
+    return config.block_align;
+}
+
+uint16_t WAV_Reader::bits_per_sample() {
+    return config.bits_per_sample;
+}
+
+/** Private **/
+
+int WAV_Reader::read_bytes(FILE *fp, char* out, int len_to_read, int start_off) {
+    fseek(fp, start_off, SEEK_SET);
+
+    for (int i = 0; i < len_to_read; i++) {
+        out[i] = fgetc(fp);
+    }
+
+    return len_to_read;
+
+}
+
+bool WAV_Reader::check_bytes(FILE *fp, char* check, int len, int start) {
+    bool success = false;
+    char extracted[len + 1];
+
+    read_bytes(fp, extracted, len, start);
+    extracted[len] = 0;
+
+    success = strcmp(extracted, check) == 0;
+
+    return success;
+}
+
+uint32_t WAV_Reader::read_num(FILE *fp, int len, int start) {
+    char extracted[len];
+    read_bytes(fp, extracted, len, start);
+
+    return get_num(extracted, len);
+}
+
+uint32_t WAV_Reader::get_num(char input[], int byte_count) {
+
+    uint32_t output = 0;
+    for (int i = 0; i < byte_count; i++) {
+        // numbers are stored least significant byte in the WAV header. So reverse and add to find the number
+        output += input[i] << (i * 8);
+    }
+
+    return output;
+
+}
+
+int WAV_Reader::find_chunk(FILE *fp, char* check, int max_len, int start) {
+    int result = -1;
+    char extracted[5];
+    int pos = start;
+
+    while ((pos + 8) < max_len && result == -1) {
+        if (check_bytes(fp, check, 4, pos)) result = pos;
+        else pos += read_num(fp, 4, pos + 4) + 8;
+    }
+
+    return result;
+
+}
+
+int WAV_Reader::move_read_position(int count, int start) {
+    _current_pos = start + count;
+    if (_current_pos > config.data_length) {
+        if (loop()) _current_pos %= config.data_length;
+        else _current_pos = config.data_length;
+    }
+
+    return _current_pos;
+}