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|
use fmt;
use endian;
use strings;
use io;
use os;
use strconv;
def HEADER: [4]u8 = ['M', 'T', 'h', 'd'];
def TRACK: [4]u8 = ['M', 'T', 'r', 'k'];
def SOUNDOFF: [2]u8 = [0x78, 0x00];
export type chunk = struct {
chktype: [4]u8,
length: u32,
};
export type hchunk = struct {
chk: chunk,
format: u16,
ntrks: u16,
division: u16,
};
export type trchunk = struct {
chk: chunk,
ev: []event,
};
export type vlen = u32;
export type event = struct {
deltatime: vlen,
ev: (midi | sysex | meta),
};
export type midi = struct {
status: u8,
data: [2]u8,
};
export type sysex = void;
export type meta = void;
export def HEADERCHUNK = chunk {
chktype = HEADER,
// MIDI 1.0
length = 6,
};
def TRACKCHUNK = chunk {
chktype = TRACK,
...
};
export type note = enum u8 {
A = 0x39,
AS = 0x3A,
B = 0x3B,
BS = 0x3C,
C = 0x3C,
CS = 0x3D,
D = 0x3E,
DS = 0x3F,
E = 0x40,
ES = 0x41,
F = 0x41,
FS = 0x42,
G = 0x43,
GS = 0x44,
};
export fn finishtrack(c: trchunk) void = {
free(c.ev);
};
export fn newtrack() trchunk = {
return trchunk {
chk = TRACKCHUNK,
ev = [],
};
};
export fn addevent(c: *trchunk, e: event) void = {
append(c.ev, e);
};
export fn playnote(d: vlen, n: note, vel: u8 = 0x40, oct: uint = 0) (event, event) = {
const eon = noteon(0, n, vel, oct);
const eoff = noteoff(d, n, vel, oct);
return (eon, eoff);
};
export fn noteon(d: vlen, n: note, vel: u8 = 0x40, oct: uint = 0) event = {
const np = n + (oct * 12): u8;
const e = event {
deltatime = d,
ev = midi {
status = 0x90,
data = [np, vel],
},
};
return e;
};
export fn noteoff(d: vlen, n: note, vel: u8 = 0x40, oct: uint = 0) event= {
const np = n + (oct * 12): u8;
const e = event {
deltatime = d,
ev = midi {
status = 0x80,
data = [np, vel],
},
};
return e;
};
export fn writeheader(h: io::handle, c: hchunk) void = {
io::writeall(h, c.chk.chktype)!;
let buf: [4]u8 = [0...];
let l = c.chk.length;
endian::beputu32(buf, l);
io::writeall(h, buf)!;
let bf: [2]u8 = [0...];
endian::beputu16(bf, c.format);
io::writeall(h, bf)!;
let bf: [2]u8 = [0...];
endian::beputu16(bf, c.ntrks);
io::writeall(h, bf)!;
let bf: [2]u8 = [0...];
endian::beputu16(bf, c.division);
io::writeall(h, bf)!;
};
export fn writechunk(h: io::handle, c: trchunk) void = {
io::writeall(h, c.chk.chktype)!;
let buf: [4]u8 = [0...];
let l = calclength(c);
//let l = c.chk.length;
endian::beputu32(buf, l);
io::writeall(h, buf)!;
writeevents(h, c.ev...);
};
export fn writeevents(h: io::handle, evs: event...) void = {
let buf: [4]u8 = [0...];
for (const ev .. evs) {
let dt = encodevlen(ev.deltatime);
endian::beputu32(buf, dt);
if (dt <= 127) {
io::writeall(h, [buf[3]])!;
} else if (dt <= 0xFF7F) {
io::writeall(h, buf[2..])!;
} else if (dt <= 0xFFFF7F) {
io::writeall(h, buf[1..])!;
} else {
io::writeall(h, buf)!;
};
match (ev.ev) {
case let m: midi =>
writemidievents(h, m);
case =>
abort();
};
};
};
export fn writemidievents(h: io::handle, evs: midi...) void = {
let buf: [4]u8 = [0...];
for (const ev .. evs) {
io::writeall(h, [ev.status])!;
io::writeall(h, ev.data)!;
};
};
fn calclength(c: trchunk) u32 = {
let length = 0u32;
for (const ev .. c.ev) {
let dt = encodevlen(ev.deltatime);
if (dt <= 127) {
length += 1;
} else if (dt <= 0xFF7F) {
length += 2;
} else if (dt <= 0xFFFF7F) {
length += 3;
} else {
length += 4;
};
match (ev.ev) {
case let m: midi =>
length += 3;
case =>
abort();
};
};
return length;
};
fn encodevlen(v: vlen) u32 = {
if (v < 128) {
return v;
};
let n = v: u32;
let b: [4]u8 = [0...];
endian::beputu32(b, v);
for (let i = 3z; i >= 0; i -= 1) {
b[i] = (n & 0x7F): u8;
if (i < 3) {
b[i] |= 0x80;
};
n >>= 7;
if (n < 1) {
break;
};
};
return endian::begetu32(b);
};
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