initHEADmain

1 files changed, 233 insertions, 0 deletions

diff --git a/mod/delay.c b/mod/delay.c
new file mode 100644
index 0000000..44441cf
--- /dev/null
+++ b/mod/delay.c
@@ -0,0 +1,233 @@
+/*
+ * melisma - extensible and scriptable audio engine
+ * Copyright (C) 2026  Ludvig Gunne Lindström
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <stdlib.h>
+#include <lauxlib.h>
+#include "melisma.h"
+#include "mutil.h"
+
+#define DELAY_TYPENAME "delay"
+
+#define MAX_DELAY         2.00f
+#define DEFAULT_DELAY     0.25f
+#define DEFAULT_GAIN      1.00f
+#define DEFAULT_FEEDBACK  0.25f
+#define DEFAULT_WETDRYMIX 0.50f
+
+#define CLAMP(v,min,max) ((v)<(min)?(min):((v)>(max)?(max):(v)))
+
+struct delay
+{
+	ml_channel *out;
+	float       feedback;
+	float       gain;
+	float       wetdrymix;
+	float       delay;
+	size_t      len;
+	size_t      write;
+	float      *buffer;
+};
+
+static void proc(const ml_proc_args *args)
+{
+	struct delay *dl = args->userp;
+
+	size_t sr = ml_sample_rate();
+	size_t offset = sr*dl->delay;
+
+	const float *in = args->in[0];
+	float *out = args->out[0];
+
+	size_t read;
+	float dry,wet;
+
+	for (size_t i = 0; i < args->nframes; i++)
+	{
+		read = dl->write + dl->len - offset;
+
+		if (read >= dl->len)
+		{
+			read -= dl->len;
+		}
+
+		dry = in[i];
+		wet = dl->buffer[read]*dl->gain;
+
+		out[i] = wet*dl->wetdrymix + dry*(1 - dl->wetdrymix);
+		dl->buffer[dl->write++] = dry + wet*dl->feedback;
+
+		if (dl->write == dl->len)
+		{
+			dl->write = 0;
+		}
+	}
+}
+
+static void clamp(struct delay *dl)
+{
+	dl->delay = CLAMP(dl->delay,0,MAX_DELAY);
+	dl->gain = CLAMP(dl->gain,0,1);
+	dl->feedback = CLAMP(dl->feedback,0,1);
+	dl->wetdrymix = CLAMP(dl->wetdrymix,0,1);
+}
+
+static int l_init(lua_State *s)
+{
+	ml_channel *src = mutil_get_channel(s,1);
+
+	struct delay *dl = calloc(1,sizeof(*dl));
+
+	dl->delay = DEFAULT_DELAY;
+	dl->gain = DEFAULT_GAIN;
+	dl->feedback = DEFAULT_FEEDBACK;
+	dl->wetdrymix = DEFAULT_WETDRYMIX;
+
+	size_t sr = ml_sample_rate();
+	dl->len = sr*MAX_DELAY;
+	dl->buffer = calloc(1,dl->len*sizeof(dl->buffer[0]));
+
+	clamp(dl);
+
+	ml_node *node = ml_create_node(proc,dl);
+	ml_label_node(node,"delay");
+	ml_channel *dst = ml_add_input(node);
+	ml_connect(src,dst);
+
+	dl->out = ml_add_output(node);
+
+	*(void**) lua_newuserdata(s,sizeof(void*)) = dl;
+	luaL_setmetatable(s,DELAY_TYPENAME);
+
+	return 1;
+}
+
+static int l_out(lua_State *s)
+{
+	struct delay *dl = *(void**) luaL_checkudata(s,1,DELAY_TYPENAME);
+	*(void**) lua_newuserdata(s,sizeof(void*)) = dl->out;
+	luaL_setmetatable(s,MELISMA_OUTPUT_CHANNEL_TYPENAME);
+	return 1;
+}
+
+static int l_delay(lua_State *s)
+{
+	struct delay *dl = *(void**) luaL_checkudata(s,1,DELAY_TYPENAME);
+	float v = luaL_checknumber(s,2);
+	dl->delay = v;
+	clamp(dl);
+	*(void**) lua_newuserdata(s,sizeof(void*)) = dl;
+	luaL_setmetatable(s,DELAY_TYPENAME);
+	return 1;
+}
+
+static int l_gain(lua_State *s)
+{
+	struct delay *dl = *(void**) luaL_checkudata(s,1,DELAY_TYPENAME);
+	float v = luaL_checknumber(s,2);
+	dl->gain = v;
+	clamp(dl);
+	*(void**) lua_newuserdata(s,sizeof(void*)) = dl;
+	luaL_setmetatable(s,DELAY_TYPENAME);
+	return 1;
+}
+
+static int l_feedback(lua_State *s)
+{
+	struct delay *dl = *(void**) luaL_checkudata(s,1,DELAY_TYPENAME);
+	float v = luaL_checknumber(s,2);
+	dl->feedback = v;
+	clamp(dl);
+	*(void**) lua_newuserdata(s,sizeof(void*)) = dl;
+	luaL_setmetatable(s,DELAY_TYPENAME);
+	return 1;
+}
+
+static int l_wetdrymix(lua_State *s)
+{
+	struct delay *dl = *(void**) luaL_checkudata(s,1,DELAY_TYPENAME);
+	float v = luaL_checknumber(s,2);
+	dl->wetdrymix = v;
+	clamp(dl);
+	*(void**) lua_newuserdata(s,sizeof(void*)) = dl;
+	luaL_setmetatable(s,DELAY_TYPENAME);
+	return 1;
+}
+
+int luaopen_melisma_delay(lua_State *s)
+{
+	ml_check_version();
+
+/*** Digital delay line.
+@classmod delay
+*/
+	lua_newtable(s);
+	int tbl = lua_gettop(s);
+
+/*** Create a delay line.
+@static
+@function init
+@tparam channel input Input signal.
+@treturn delay Newly created delay line.
+*/
+	lua_pushcfunction(s,l_init);
+	lua_setfield(s,tbl,"init");
+
+/*** Set delay.
+@function delay
+@tparam number d delay in seconds.
+@treturn delay
+*/
+	lua_pushcfunction(s,l_delay);
+	lua_setfield(s,tbl,"delay");
+
+/*** Set gain.
+@function gain
+@tparam number g Gain (**TODO**: Use decibels).
+@treturn delay
+*/
+	lua_pushcfunction(s,l_gain);
+	lua_setfield(s,tbl,"gain");
+
+/*** Set feedback.
+@function feedback
+@tparam number f Feedback.
+@treturn delay
+*/
+	lua_pushcfunction(s,l_feedback);
+	lua_setfield(s,tbl,"feedback");
+
+/*** Set wet/dry mix.
+@function wetdrymix
+@tparam number wd Wet/dry mix.
+@treturn delay
+*/
+	lua_pushcfunction(s,l_wetdrymix);
+	lua_setfield(s,tbl,"wetdrymix");
+
+	lua_pushcfunction(s,l_out);
+	lua_setfield(s,tbl,MUTIL_OUTPUT_CHANNEL_FUNCTION);
+
+	luaL_newmetatable(s,DELAY_TYPENAME);
+	int mt = lua_gettop(s);
+
+	lua_pushvalue(s,tbl);
+	lua_setfield(s,mt,"__index");
+
+	lua_settop(s,tbl);
+	return 1;
+}