optimize main plugin loop

this makes it faster to have the main loop focus on running the actual
plugin while pre- and post- parts of the loop become their own thing
with bigger buffers.
This commit is contained in:
Luna 2019-07-10 22:28:34 -03:00
parent 2d9fe80395
commit 542c239e0c

View file

@ -7,6 +7,9 @@ const plugins = @import("plugin.zig");
/// Approximate size of the BMP header.
pub const BMPHeaderSize: usize = 82000;
/// Buffer size for main copying
pub const BufferSize: usize = 60000;
pub const ImageError = error{
OpenFail,
InvalidPlugin,
@ -155,6 +158,34 @@ pub const Image = struct {
return n_read == 1;
}
fn copyBytes(
self: *Image,
out_file: *c.SNDFILE,
buf: []f32,
start: usize,
end: usize,
) !void {
const total_bytes = end - start;
var i: usize = start;
while (i < end) : (i += buf.len) {
const read_bytes = c.sf_readf_float(self.sndfile, buf.ptr, @intCast(i64, buf.len));
var view: []f32 = buf[0..buf.len];
if (i + buf.len > end) {
const excess = i + buf.len - end;
view = buf[0..excess];
_ = c.sf_seek(
self.sndfile,
-@intCast(i64, excess),
c.SEEK_CUR,
);
}
try swrite(out_file, view.ptr, @intCast(i64, view.len));
}
}
/// Run a plugin over the image.
/// This setups a new lilv world/plugin among other things.
/// The internal SNDFILE pointer is modified to point to the output of the
@ -228,28 +259,52 @@ pub const Image = struct {
// make sure we start from 0
_ = c.sf_seek(self.sndfile, 0, c.SEEK_SET);
var i: usize = 0;
// there are four main stages:
// - the bmp header copy
// - pre-plugin
// - plugin
// - post-plugin
while (i < file_end) : (i += 1) {
// if we're still on the bmp header phase, copy bytes
// if we aren't in the range from seek_pos, copy bytes
// if we are in the range, run lilv plugin
var header_buf = try self.allocator.alloc(f32, BMPHeaderSize);
defer self.allocator.free(header_buf);
// TODO speed this up by not reading byte-by-byte.
var file_copy_buf = try self.allocator.alloc(f32, BufferSize);
defer self.allocator.free(file_copy_buf);
// bmp header copy
const header_len = @intCast(i64, header_buf.len);
_ = c.sf_readf_float(self.sndfile, header_buf.ptr, header_len);
try swrite(out_file, header_buf.ptr, header_len);
// pre-plugin copy
try self.copyBytes(
out_file,
file_copy_buf,
BMPHeaderSize,
seek_pos.start,
);
var i: usize = seek_pos.start;
while (i < seek_pos.end) : (i += 1) {
const read_bytes = c.sf_readf_float(self.sndfile, rctx.in_buf.ptr, 1);
if (read_bytes == 0) {
std.debug.warn("WARN! reached EOF at idx={}\n", i);
break;
}
if (i < BMPHeaderSize or !seek_pos.contains(i)) {
try swrite(out_file, rctx.in_buf.ptr, 1);
} else {
lv2.lilv_instance_run(rctx.instance, 1);
try swrite(out_file, rctx.out_buf.ptr, 1);
}
lv2.lilv_instance_run(rctx.instance, 1);
try swrite(out_file, rctx.out_buf.ptr, 1);
}
// post-plugin copy
try self.copyBytes(
out_file,
file_copy_buf,
seek_pos.end,
file_end,
);
c.sf_write_sync(out_file);
_ = c.sf_close(out_file);
_ = c.sf_close(self.sndfile);