Initial export code to SBI file format

Author: fragglet

src/GNUmakefile

@@ -76,8 +76,10 @@ OBJS =                      \
     fs/vfs.o                \
     fs/wad_dir.o            \
     fs/wad_file.o           \
+    genmidi/actions.o       \
     genmidi/genmidi.o       \
     genmidi/genmidi_dir.o   \
+    genmidi/sbi_file.o      \
     pager/help.o            \
     pager/hexdump.o         \
     pager/pager.o           \

src/browser/browser.c

@@ -219,6 +219,7 @@ static const struct action *pal_actions[] = {
 static const struct action *opl_actions[] = {
     &parent_dir_action,
     &view_action,
+    &genmidi_export_action,
     NULL,
 };
 

src/genmidi/actions.c

@@ -0,0 +1,42 @@
+//
+// Copyright(C) 2025 Simon Howard
+//
+// You can redistribute and/or modify this program under the terms of
+// the GNU General Public License version 2 as published by the Free
+// Software Foundation, or any later version. This program is
+// distributed WITHOUT ANY WARRANTY; without even the implied warranty
+// of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+//
+
+#include <assert.h>
+#include <ncurses.h>
+
+#include "browser/browser.h"
+#include "browser/directory_pane.h"
+#include "common.h"
+#include "fs/vfile.h"
+#include "genmidi/genmidi.h"
+#include "ui/actions_bar.h"
+
+static void ActionExportVoice(void)
+{
+	struct genmidi_bank *bank = GENMIDI_DirGetBank(active_pane->dir);
+	struct genmidi_instrument *instr;
+	int selected = B_DirectoryPaneSelected(active_pane);
+	VFILE *out;
+
+	if (selected < 0) {
+		return;
+	}
+
+	instr = &bank->instrs[selected / 2];
+
+	// TODO: Write to the correct directory
+	out = vfwrapfile(fopen("foo.sbi", "wb"));
+	GENMIDI_WriteSBI(instr, (selected % 2) != 0, out);
+	vfclose(out);
+}
+
+const struct action genmidi_export_action = {
+    KEY_F(5), 'C', "Export", "> Export", ActionExportVoice,
+};

src/genmidi/genmidi.h

@@ -56,14 +56,19 @@ struct genmidi_bank {
 	struct genmidi_instrument instrs[NUM_GENMIDI_INSTRS];
 };
 
+struct action;
 struct directory_entry;
 struct file_type;
 
 extern const struct file_type file_type_genmidi_bank;
 extern const struct file_type file_type_genmidi_voice;
+extern const struct action genmidi_export_action;
 
 bool GENMIDI_LoadBank(struct genmidi_bank *bank, VFILE *in);
 struct directory *GENMIDI_OpenDir(struct directory *parent,
                                   struct directory_entry *ent);
+struct genmidi_bank *GENMIDI_DirGetBank(struct directory *dir);
+bool GENMIDI_WriteSBI(struct genmidi_instrument *instr, bool voice2,
+                      VFILE *out);
 
 #endif /* #ifndef GENMIDI__GENMIDI_H_INCLUDED */

src/genmidi/genmidi_dir.c

@@ -26,6 +26,12 @@ struct genmidi_dir {
 const struct file_type file_type_genmidi_bank = {"GENMIDI bank"};
 const struct file_type file_type_genmidi_voice = {"Voice"};
 
+struct genmidi_bank *GENMIDI_DirGetBank(struct directory *_dir)
+{
+	struct genmidi_dir *dir = (struct genmidi_dir *) _dir;
+	return &dir->bank;
+}
+
 static const char *InstrumentNumber(int index)
 {
 	static char buf[8];

src/genmidi/sbi_file.c

@@ -0,0 +1,66 @@
+//
+// Copyright(C) 2025 Simon Howard
+//
+// You can redistribute and/or modify this program under the terms of
+// the GNU General Public License version 2 as published by the Free
+// Software Foundation, or any later version. This program is
+// distributed WITHOUT ANY WARRANTY; without even the implied warranty
+// of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+//
+
+#include <assert.h>
+#include <ncurses.h>
+
+#include "common.h"
+#include "fs/vfile.h"
+#include "genmidi/genmidi.h"
+
+#define HEADER_VALUE "SBI\x1a"
+
+static const int sbi_field_mapping[] = {
+    INSTR_M_AM_VIBRATO_EG,   // 0
+    INSTR_C_AM_VIBRATO_EG,   // 1
+    INSTR_M_KSL,             // 2 ; _VOLUME is |ed in below
+    INSTR_C_KSL,             // 3 ; _VOLUME is |ed in below
+    INSTR_M_ATTACK_DECAY,    // 4
+    INSTR_C_ATTACK_DECAY,    // 5
+    INSTR_M_SUSTAIN_RELEASE, // 6
+    INSTR_C_SUSTAIN_RELEASE, // 7
+    INSTR_M_WAVEFORM,        // 8
+    INSTR_C_WAVEFORM,        // 9
+    INSTR_FEEDBACK_FM,       // 10
+};
+
+bool GENMIDI_WriteSBI(struct genmidi_instrument *instr, bool voice2, VFILE *out)
+{
+	uint8_t *voicedata;
+	uint8_t buf[16];
+	int i;
+
+	if (vfwrite(HEADER_VALUE, 4, 1, out) != 1 ||
+	    vfwrite(instr->name, 32, 1, out) != 1) {
+		return false;
+	}
+
+	if (voice2) {
+		voicedata = instr->voice2;
+	} else {
+		voicedata = instr->voice1;
+	}
+
+	memset(buf, 0, sizeof(buf));
+	for (i = 0; i < arrlen(sbi_field_mapping); ++i) {
+		buf[i] = voicedata[sbi_field_mapping[i]];
+	}
+
+	buf[2] |= voicedata[INSTR_M_VOLUME];
+	buf[3] |= voicedata[INSTR_C_VOLUME];
+	buf[12] = voicedata[INSTR_NOTE_OFFSET];
+
+	if ((instr->hdr.flags & GENMIDI_FLAG_FIXED) != 0) {
+		buf[11] = 1;
+		buf[13] = instr->hdr.fixed_note;
+	}
+
+	return vfwrite(buf, 16, 1, out) == 1;
+}