Added simple Golang example

3 files changed, 146 insertions, 0 deletions

diff --git a/examples/golang-mid2wav/.gitignore b/examples/golang-mid2wav/.gitignore
new file mode 100644
index 0000000..6f02588
--- /dev/null
+++ b/examples/golang-mid2wav/.gitignore
@@ -0,0 +1,2 @@
+mid2wav
+mid2wav.exe
diff --git a/examples/golang-mid2wav/README.txt b/examples/golang-mid2wav/README.txt
new file mode 100644
index 0000000..055b9cd
--- /dev/null
+++ b/examples/golang-mid2wav/README.txt
@@ -0,0 +1,15 @@
+To build this example, run the next command from a terminal:
+------------------------------
+go build mid2wav.go
+------------------------------
+
+Usage of ./mid2wav:
+  -b int
+        bank (default 59)
+  -c int
+        chips (default 2)
+  -i string
+        input midi file
+  -o string
+        output wave file
+------------------------------
diff --git a/examples/golang-mid2wav/mid2wav.go b/examples/golang-mid2wav/mid2wav.go
new file mode 100644
index 0000000..d8fc059
--- /dev/null
+++ b/examples/golang-mid2wav/mid2wav.go
@@ -0,0 +1,129 @@
+package main
+
+import (
+    "flag"
+    "log"
+    "unsafe"
+)
+
+// #cgo LDFLAGS: -lADLMIDI -Lbin
+// #cgo CFLAGS:
+// #include <stdio.h>
+// #include <stdlib.h>
+// #include <adlmidi.h>
+// typedef struct wav_header {
+//     // RIFF Header
+//     char riff_header[4]; // Contains "RIFF"
+//     int wav_size; // Size of the wav portion of the file, which follows the first 8 bytes. File size - 8
+//     char wave_header[4]; // Contains "WAVE"
+//     // Format Header
+//     char fmt_header[4]; // Contains "fmt " (includes trailing space)
+//     int fmt_chunk_size; // Should be 16 for PCM
+//     short audio_format; // Should be 1 for PCM. 3 for IEEE Float
+//     short num_channels;
+//     int sample_rate;
+//     int byte_rate; // Number of bytes per second. sample_rate * num_channels * Bytes Per Sample
+//     short sample_alignment; // num_channels * Bytes Per Sample
+//     short bit_depth; // Number of bits per sample
+//     // Data
+//     char data_header[4]; // Contains "data"
+//     int data_bytes; // Number of bytes in data. Number of samples * num_channels * sample byte size
+//     // uint8_t bytes[]; // Remainder of wave file is bytes
+// } wav_header;
+import "C"
+
+func main() {
+    inputPtr := flag.String("i", "", "input midi file")
+    outputPtr := flag.String("o", "", "output wave file")
+    bank := flag.Int("b", 59, "bank")
+    chips := flag.Int("c", 2, "chips")
+
+    flag.Parse()
+
+    if *inputPtr == "" {
+	    log.Fatal("no input midi file")
+    }
+
+    if *outputPtr == "" {
+	    log.Fatal("no output file")
+    }
+
+    // Convert into raw C-String
+    cInputFile := C.CString(*inputPtr)
+
+    // Initializing the instance of libADLMIDI
+    cAdlMidiPlayer := C.adl_init(48000)
+    // Set number of parallel chips
+    C.adl_setNumChips(cAdlMidiPlayer, C.int(*chips))
+    // Disable looping (it's not needed for WAV output)
+    C.adl_setLoopEnabled(cAdlMidiPlayer, 0)
+    // Setting one of embedded banks
+    C.adl_setBank(cAdlMidiPlayer, C.int(*bank))
+    // Open an external MIDI file to play it
+    C.adl_openFile(cAdlMidiPlayer, cInputFile)
+    // Remove the file path buffer
+    C.free(unsafe.Pointer(cInputFile))
+
+    // Create the audio buffer that will be used to store taken audio chunks and write them into WAV file
+    cBuffer := C.malloc(2048 * 2)
+
+    cOutputFileName := C.CString(*outputPtr)
+    cFileMode := C.CString("wb")
+
+    cFILE := C.fopen(cOutputFileName, cFileMode)
+    C.free(unsafe.Pointer(cOutputFileName))
+    C.free(unsafe.Pointer(cFileMode))
+
+    var cWavHeader C.wav_header
+    cWavHeader.riff_header[0] = 'R'
+    cWavHeader.riff_header[1] = 'I'
+    cWavHeader.riff_header[2] = 'F'
+    cWavHeader.riff_header[3] = 'F'
+    cWavHeader.wav_size = 0
+    cWavHeader.wave_header[0] = 'W'
+    cWavHeader.wave_header[1] = 'A'
+    cWavHeader.wave_header[2] = 'V'
+    cWavHeader.wave_header[3] = 'E'
+    cWavHeader.fmt_header[0] = 'f'
+    cWavHeader.fmt_header[1] = 'm'
+    cWavHeader.fmt_header[2] = 't'
+    cWavHeader.fmt_header[3] = ' '
+    cWavHeader.fmt_chunk_size = 16
+    cWavHeader.audio_format = 1
+    cWavHeader.num_channels = 2
+    cWavHeader.sample_rate = 48000
+    cWavHeader.byte_rate = 192000
+    cWavHeader.sample_alignment = 4
+    cWavHeader.bit_depth = 16
+    cWavHeader.data_header[0] = 'd'
+    cWavHeader.data_header[1] = 'a'
+    cWavHeader.data_header[2] = 't'
+    cWavHeader.data_header[3] = 'a'
+    cWavHeader.data_bytes = 0
+
+    C.fwrite(unsafe.Pointer(&cWavHeader), 44, 1, cFILE)
+
+    finished := false
+    dataBytes := 0
+
+    for !finished {
+        count := C.adl_play(cAdlMidiPlayer, 2048, (*C.int16_t)(cBuffer))
+        if C.adl_atEnd(cAdlMidiPlayer) == 1 {
+            finished = true
+        }
+        if count > 0 {
+            dataBytes += int(count) * 4
+            C.fwrite(cBuffer, 1, C.size_t(count * 2), cFILE)
+        }
+    }
+    C.adl_close(cAdlMidiPlayer)
+
+    cWavHeader.wav_size = C.int(36 + dataBytes)
+    cWavHeader.data_bytes = C.int(dataBytes)
+
+    C.fseek(cFILE, 0, C.SEEK_SET)
+    C.fwrite(unsafe.Pointer(&cWavHeader), 44, 1, cFILE)
+
+    C.fclose(cFILE)
+    C.free(cBuffer)
+}