+/* midi.c
+ *
+ * Adlib OPL2/OPL3 FM synthesizer chipset test program.
+ * Play MIDI file using the OPLx synthesizer (well, poorly anyway)
+ * (C) 2010-2012 Jonathan Campbell.
+ * Hackipedia DOS library.
+ *
+ * This code is licensed under the LGPL.
+ * <insert LGPL legal text here>
+ *
+ * Compiles for intended target environments:
+ * - MS-DOS [pure DOS mode, or Windows or OS/2 DOS Box]
+ */
+
+#include <stdio.h>
+#include <conio.h> /* this is where Open Watcom hides the outp() etc. functions */
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <malloc.h>
+#include <ctype.h>
+#include <fcntl.h>
+#include <math.h>
+#include <dos.h>
+
+#include <hw/vga/vga.h>
+#include <hw/dos/dos.h>
+#include <hw/8254/8254.h> /* 8254 timer */
+#include <hw/8259/8259.h>
+#include <hw/adlib/adlib.h>
+
+static void (interrupt *old_irq0)();
+static volatile unsigned long irq0_ticks=0;
+static volatile unsigned int irq0_cnt=0,irq0_add=0,irq0_max=0;
+
+#pragma pack(push,1)
+struct imf_entry {
+ uint8_t reg,data;
+ uint16_t delay;
+};
+#pragma pack(pop)
+
+static struct imf_entry* imf_music=NULL;
+static struct imf_entry* imf_play_ptr=NULL;
+static struct imf_entry* imf_music_end=NULL;
+static uint16_t imf_delay_countdown=0;
+
+void imf_free_music() {
+ if (imf_music) free(imf_music);
+ imf_music = imf_play_ptr = imf_music_end = NULL;
+ imf_delay_countdown = 0;
+}
+
+int imf_load_music(const char *path) {
+ unsigned char buf[8];
+ unsigned long len;
+ int fd;
+
+ imf_free_music();
+
+ fd = open(path,O_RDONLY|O_BINARY);
+ if (fd < 0) return 0;
+
+ len = lseek(fd,0,SEEK_END);
+ lseek(fd,0,SEEK_SET);
+ read(fd,buf,2);
+ if (buf[0] != 0 || buf[1] != 0) // type 1 IMF
+ len = *((uint16_t*)buf);
+ else
+ lseek(fd,0,SEEK_SET);
+
+ if (len == 0 || len > 65535UL) {
+ close(fd);
+ return 0;
+ }
+ len -= len & 3;
+
+ imf_music = malloc(len);
+ if (imf_music == NULL) {
+ close(fd);
+ return 0;
+ }
+ read(fd,imf_music,len);
+ close(fd);
+
+ imf_play_ptr = imf_music;
+ imf_music_end = imf_music + (len >> 2UL);
+ return 1;
+}
+
+/* WARNING: subroutine call in interrupt handler. make sure you compile with -zu flag for large/compact memory models */
+void interrupt irq0() {
+ irq0_ticks++;
+ if ((irq0_cnt += irq0_add) >= irq0_max) {
+ irq0_cnt -= irq0_max;
+ old_irq0();
+ }
+ else {
+ p8259_OCW2(0,P8259_OCW2_NON_SPECIFIC_EOI);
+ }
+}
+
+void imf_tick() {
+ if (imf_delay_countdown == 0) {
+ do {
+ adlib_write(imf_play_ptr->reg,imf_play_ptr->data);
+ imf_delay_countdown = imf_play_ptr->delay;
+ imf_play_ptr++;
+ if (imf_play_ptr == imf_music_end)
+ imf_play_ptr = imf_music;
+ } while (imf_delay_countdown == 0);
+ }
+ else {
+ imf_delay_countdown--;
+ }
+}
+
+void adlib_shut_up() {
+ int i;
+
+ memset(adlib_fm,0,sizeof(adlib_fm));
+ memset(&adlib_reg_bd,0,sizeof(adlib_reg_bd));
+ for (i=0;i < adlib_fm_voices;i++) {
+ struct adlib_fm_operator *f;
+ f = &adlib_fm[i].mod;
+ f->ch_a = f->ch_b = f->ch_c = f->ch_d = 1;
+ f = &adlib_fm[i].car;
+ f->ch_a = f->ch_b = f->ch_c = f->ch_d = 1;
+ }
+
+ for (i=0;i < adlib_fm_voices;i++) {
+ struct adlib_fm_operator *f;
+
+ f = &adlib_fm[i].mod;
+ f->mod_multiple = 1;
+ f->total_level = 63 - 16;
+ f->attack_rate = 15;
+ f->decay_rate = 4;
+ f->sustain_level = 0;
+ f->release_rate = 8;
+ f->f_number = 400;
+ f->sustain = 1;
+ f->octave = 4;
+ f->key_on = 0;
+
+ f = &adlib_fm[i].car;
+ f->mod_multiple = 1;
+ f->total_level = 63 - 16;
+ f->attack_rate = 15;
+ f->decay_rate = 4;
+ f->sustain_level = 0;
+ f->release_rate = 8;
+ f->f_number = 0;
+ f->sustain = 1;
+ f->octave = 0;
+ f->key_on = 0;
+ }
+
+ adlib_apply_all();
+}
+
+int main(int argc,char **argv) {
+ unsigned long tickrate = 700;
+ unsigned long ptick;
+ int c;
+
+ printf("ADLIB FM test program IMFPLAY\n");
+ if (argc < 2) {
+ printf("You must specify an IMF file to play\n");
+ return 1;
+ }
+
+ if (!init_adlib()) {
+ printf("Cannot init library\n");
+ return 1;
+ }
+ if (!probe_8254()) { /* we need the timer to keep time with the music */
+ printf("8254 timer not found\n");
+ return 1;
+ }
+
+ if (!imf_load_music(argv[1])) {
+ printf("Failed to load IMF Music\n");
+ return 1;
+ }
+
+ write_8254_system_timer(T8254_REF_CLOCK_HZ / tickrate);
+ irq0_cnt = 0;
+ irq0_add = 182;
+ irq0_max = 1000; /* about 18.2Hz */
+ old_irq0 = _dos_getvect(8);/*IRQ0*/
+ _dos_setvect(8,irq0);
+
+ adlib_shut_up();
+ shutdown_adlib_opl3(); // NTS: Apparently the music won't play otherwise
+ _cli();
+ irq0_ticks = ptick = 0;
+ _sti();
+
+ while (1) {
+ unsigned long adv;
+
+ _cli();
+ adv = irq0_ticks - ptick;
+ if (adv >= 100UL) adv = 100UL;
+ ptick = irq0_ticks;
+ _sti();
+
+ while (adv != 0) {
+ imf_tick();
+ adv--;
+ }
+
+ if (kbhit()) {
+ c = getch();
+ if (c == 0) c = getch() << 8;
+
+ if (c == 27) {
+ break;
+ }
+ }
+ }
+
+ imf_free_music();
+ adlib_shut_up();
+ shutdown_adlib();
+ _dos_setvect(8,old_irq0);
+ write_8254_system_timer(0); /* back to normal 18.2Hz */
+ return 0;
+}
+