1 files changed, 96 insertions, 0 deletions
diff --git a/src/utils.cpp b/src/utils.cpp
new file mode 100644
index 0000000..525f05e
--- /dev/null
+++ b/src/utils.cpp
@@ -0,0 +1,96 @@
+#include <cmath>
+#include <cstdint>
+#include <cstddef>
+#include <sstream>
+
+#include "utils.h"
+#include <unistd.h>
+
+#define MIN(a,b) (((a)<(b))?(a):(b))
+#define MAX(a,b) (((a)>(b))?(a):(b))
+
+/* Taken from sox */
+const char* level(int channel, int peak)
+{
+    static char const * const text[][2] = {
+        /* White: 2dB steps */
+        {"", ""}, {"-", "-"}, {"=", "="}, {"-=", "=-"},
+        {"==", "=="}, {"-==", "==-"}, {"===", "==="}, {"-===", "===-"},
+        {"====", "===="}, {"-====", "====-"}, {"=====", "====="},
+        {"-=====", "=====-"}, {"======", "======"},
+        /* Red: 1dB steps */
+        {"!=====", "=====!"},
+    };
+    int const red = 1, white = NUMOF(text) - red;
+
+    double linear = ((double)peak) / INT16_MAX;
+
+    int vu_dB = linear ? floor(2 * white + red + linear_to_dB(linear)) : 0;
+
+    int index = vu_dB < 2 * white ?
+        MAX(vu_dB / 2, 0) :
+        MIN(vu_dB - white, red + white - 1);
+
+    return text[index][channel];
+}
+
+size_t strlen_utf8(const char *s) {
+    size_t result = 0;
+
+    // ignore continuation bytes - only count single/leading bytes
+    while (*s)
+        if ((*s++ & 0xC0) != 0x80)
+            result++;
+
+    return result;
+}
+
+static const std::string ICY_TEXT_SEPARATOR = " - ";
+
+bool write_icy_to_file(const ICY_TEXT_t text, const std::string& filename, bool dl_plus)
+{
+    FILE* fd = fopen(filename.c_str(), "wb");
+    if (fd) {
+        bool ret = true;
+        bool artist_title_used = !text.artist.empty() and !text.title.empty();
+
+        // if desired, prepend DL Plus information
+        if (dl_plus) {
+            std::stringstream ss;
+            ss << "##### parameters { #####\n";
+            ss << "DL_PLUS=1\n";
+
+            // if non-empty text, add tag
+            if (artist_title_used) {
+                size_t artist_len = strlen_utf8(text.artist.c_str());
+                size_t title_start = artist_len + strlen_utf8(ICY_TEXT_SEPARATOR.c_str());
+
+                // ITEM.ARTIST
+                ss << "DL_PLUS_TAG=4 0 " << (artist_len - 1) << "\n";   // -1 !
+
+                // ITEM.TITLE
+                ss << "DL_PLUS_TAG=1 " << title_start << " " << (strlen_utf8(text.title.c_str()) - 1) << "\n";   // -1 !
+            } else if (!text.now_playing.empty()) {
+                // PROGRAMME.NOW
+                ss << "DL_PLUS_TAG=33 0 " << (strlen_utf8(text.now_playing.c_str()) - 1) << "\n";   // -1 !
+            }
+
+            ss << "##### parameters } #####\n";
+            ret &= fputs(ss.str().c_str(), fd) >= 0;
+        }
+
+        if (artist_title_used) {
+            ret &= fputs(text.artist.c_str(), fd) >= 0;
+            ret &= fputs(ICY_TEXT_SEPARATOR.c_str(), fd) >= 0;
+            ret &= fputs(text.title.c_str(), fd) >= 0;
+        }
+        else {
+            ret &= fputs(text.now_playing.c_str(), fd) >= 0;
+        }
+        fclose(fd);
+
+        return ret;
+    }
+
+    return false;
+}