1 files changed, 438 insertions, 0 deletions
diff --git a/mod/oscil.c b/mod/oscil.c
new file mode 100644
index 0000000..7bc39c7
--- /dev/null
+++ b/mod/oscil.c
@@ -0,0 +1,438 @@
+/*
+ * 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 <string.h>
+#include <math.h>
+
+#include <lua.h>
+#include <lauxlib.h>
+
+#include "melisma.h"
+#include "mutil.h"
+
+#define WAVETABLE_TYPENAME "wavetable"
+#define OSCIL_TYPENAME "oscil"
+
+#ifndef WAVETABLE_SIZE
+#define WAVETABLE_SIZE 2048
+#endif
+
+#define WAVETABLE_ALLOC_SIZE (sizeof(float)*WAVETABLE_SIZE)
+
+struct oscil
+{
+	ml_node       *node;
+	unsigned long  clk;
+	float          f;
+	float          a;
+	int            mf;
+	int            ma;
+	float          p;
+	float          v;
+	float          tbl[WAVETABLE_SIZE];
+};
+
+static float *push_new_wavetable(lua_State *s)
+{
+	float *ptr = lua_newuserdata(s,WAVETABLE_ALLOC_SIZE);
+	luaL_setmetatable(s,WAVETABLE_TYPENAME);
+	memset(ptr,0,WAVETABLE_ALLOC_SIZE);
+	return ptr;
+}
+
+static int l_const(lua_State *s)
+{
+	float v = luaL_checknumber(s,1);
+	float *tbl = push_new_wavetable(s);
+
+	for (size_t i = 0; i < WAVETABLE_SIZE; i++)
+	{
+		tbl[i] = v;
+	}
+
+	return 1;
+}
+
+static int l_sin(lua_State *s)
+{
+	float *tbl = push_new_wavetable(s);
+
+	for (size_t i = 0; i < WAVETABLE_SIZE; i++)
+	{
+		float f = 2.f * M_PI * (float) i / (float) WAVETABLE_SIZE;
+		tbl[i] = sinf(f);
+	}
+
+	return 1;
+}
+
+static int l_saw(lua_State *s)
+{
+	float *tbl = push_new_wavetable(s);
+
+	for (size_t i = 0; i < WAVETABLE_SIZE; i++)
+	{
+		tbl[i] =  2 * (float) i / (float) WAVETABLE_SIZE - 1;
+	}
+
+	return 1;
+}
+
+static int l_square(lua_State *s)
+{
+	float *tbl = push_new_wavetable(s);
+
+	for (size_t i = 0; i < WAVETABLE_SIZE; i++)
+	{
+		if (i >= WAVETABLE_SIZE/2)
+		{
+			tbl[i] = 1;
+		}
+		else
+		{
+			tbl[i] = -1;
+		}
+	}
+
+	return 1;
+}
+
+static int l_shift(lua_State *s)
+{
+	float *src = luaL_checkudata(s,1,WAVETABLE_TYPENAME);
+	float p = luaL_checknumber(s,2);
+
+	while (p < 0)
+	{
+		p += 2*M_PI;
+	}
+
+	while (p > 2*M_PI)
+	{
+		p -= 2*M_PI;
+	}
+
+	size_t offset = p/2.f/M_PI*WAVETABLE_SIZE;
+	float *dst = push_new_wavetable(s);
+
+	size_t i,d;
+	for (i=0, d=offset; i < WAVETABLE_SIZE; i++, d++)
+	{
+		dst[d % WAVETABLE_SIZE] = src[i];
+	}
+
+	return 1;
+}
+
+static int l_scale(lua_State *s)
+{
+	float *src = luaL_checkudata(s,1,WAVETABLE_TYPENAME);
+	int n = luaL_checkinteger(s,2);
+
+	// if (n <= 0 || (n & (n-1)) != 0)
+	// {
+	// 	luaL_error(s,"scaling factor must be a power of two");
+	// }
+
+	float *dst = push_new_wavetable(s);
+
+	for (size_t i = 0; i < WAVETABLE_SIZE; i++)
+	{
+		size_t j = (n*i) % WAVETABLE_SIZE;
+		dst[i] = src[j];
+	}
+
+	return 1;
+}
+
+static int l_add(lua_State *s)
+{
+	float *lhs = luaL_checkudata(s,1,WAVETABLE_TYPENAME);
+	float *rhs = luaL_checkudata(s,2,WAVETABLE_TYPENAME);
+	float *res = push_new_wavetable(s);
+
+	for (size_t i = 0; i < WAVETABLE_SIZE; i++)
+	{
+		res[i] = lhs[i] + rhs[i];
+	}
+
+	return 1;
+}
+
+static void proc(const ml_proc_args *args)
+{
+	struct oscil *oscil = args->userp;
+
+	unsigned long sr = ml_sample_rate();
+	float p = oscil->p;
+	float *dst = args->out[0];
+
+	float *mf = oscil->mf < 0 ? NULL : args->in[oscil->mf];
+	float *ma = oscil->ma < 0 ? NULL : args->in[oscil->ma];
+
+	for (size_t i = 0; i < args->nframes; i++)
+	{
+		float f = mf ? mf[i] : oscil->f;
+		float a = ma ? ma[i] : oscil->a;
+
+		float t = p*WAVETABLE_SIZE;
+
+		size_t i0 = (size_t) t;
+		size_t i1 = i0 + 1;
+
+		float ip = t - i0;
+
+		i0 &= (WAVETABLE_SIZE-1);
+		i1 &= (WAVETABLE_SIZE-1);
+
+		float s0 = oscil->tbl[i0];
+		float s1 = oscil->tbl[i1];
+
+		dst[i] = a*(s0 + ip*(s1 - s0));
+
+		p += f/sr;
+
+		if (p > 1)
+		{
+			p -= 1;
+		}
+	}
+
+	oscil->p = p;
+	oscil->v = dst[args->nframes-1];
+}
+
+static int l_init(lua_State *s)
+{
+	float *tbl = luaL_checkudata(s,1,WAVETABLE_TYPENAME);
+	float f = luaL_checknumber(s,2);
+	float a = luaL_checknumber(s,3);
+
+	struct oscil *oscil = calloc(1,sizeof(*oscil));
+	oscil->clk = 0;
+	oscil->f = f;
+	oscil->a = a;
+	oscil->mf = -1;
+	oscil->ma = -1;
+	oscil->p = 0;
+	oscil->v = a*tbl[0];
+
+	ml_node *node = ml_create_node(proc,oscil);
+	ml_label_node(node,"oscil");
+	ml_add_output(node);
+	oscil->node = node;
+
+	memcpy(oscil->tbl,tbl,WAVETABLE_ALLOC_SIZE);
+
+	*(void**) lua_newuserdata(s,sizeof(void*)) = oscil;
+	luaL_setmetatable(s,OSCIL_TYPENAME);
+
+	return 1;
+}
+
+static int l_setf(lua_State *s)
+{
+	struct oscil *oscil = *(void**) luaL_checkudata(s,1,OSCIL_TYPENAME);
+	float v = luaL_checknumber(s,2);
+	oscil->f = v;
+	return 0;
+}
+
+static int l_seta(lua_State *s)
+{
+	struct oscil *oscil = *(void**) luaL_checkudata(s,1,OSCIL_TYPENAME);
+	float v = luaL_checknumber(s,2);
+	oscil->a = v;
+	return 0;
+}
+
+static int l_mapf(lua_State *s)
+{
+	struct oscil *oscil = *(void**) luaL_checkudata(s,1,OSCIL_TYPENAME);
+	ml_channel *src = mutil_get_channel(s,2);
+
+	oscil->mf = ml_num_inputs(oscil->node);
+
+	ml_channel *dst = ml_add_input(oscil->node);
+	ml_connect(src,dst);
+
+	return 0;
+}
+
+static int l_mapa(lua_State *s)
+{
+	struct oscil *oscil = *(void**) luaL_checkudata(s,1,OSCIL_TYPENAME);
+	ml_channel *src = mutil_get_channel(s,2);
+
+	oscil->ma = ml_num_inputs(oscil->node);
+
+	ml_channel *dst = ml_add_input(oscil->node);
+	ml_connect(src,dst);
+
+	return 0;
+}
+
+static int l_sample(lua_State *s)
+{
+	struct oscil *oscil = *(void**) luaL_checkudata(s,1,OSCIL_TYPENAME);
+	lua_pushnumber(s,oscil->v);
+	return 1;
+}
+
+static int l_out(lua_State *s)
+{
+	struct oscil *oscil = *(void**) luaL_checkudata(s,1,OSCIL_TYPENAME);
+	*(void**) lua_newuserdata(s,sizeof(void*)) = ml_get_output(oscil->node,0);
+	luaL_setmetatable(s,MELISMA_OUTPUT_CHANNEL_TYPENAME);
+	return 1;
+}
+
+int luaopen_melisma_oscil(lua_State *s)
+{
+
+/*** Wavetable backed oscillators.
+
+	local moscil = require 'melisma.oscil'
+	local mexpression = require 'melisma.expression'
+
+	local wt = moscil.wavetable.sin()
+
+	-- Make an LFO for controlling the frequency.
+	local lfo_oscil = moscil.init(wt,1,1)
+
+	-- Map [-1, 1] to [440, 880]
+	local lfo = (440 + (1 + mexpression.input(lfo_oscil,0) / 2) * 440):build()
+
+	local oscil = moscil.init(wt,0,0.5)
+	oscil:mapf(lfo)
+
+@classmod oscil
+*/
+	lua_newtable(s);
+	int tbl = lua_absindex(s,lua_gettop(s));
+
+/*** Initialize an oscillator.
+@static
+@function init
+@tparam wavetable wt
+@tparam number freq
+@tparam number amp
+@treturn oscil
+*/
+	lua_pushcfunction(s,l_init);
+	lua_setfield(s,tbl,"init");
+
+/*** Set oscillator frequency.
+@function setf
+@tparam number freq
+*/
+	lua_pushcfunction(s,l_setf);
+	lua_setfield(s,tbl,"setf");
+
+/*** Set oscillator amplitude.
+@function seta
+@tparam number amp
+*/
+	lua_pushcfunction(s,l_seta);
+	lua_setfield(s,tbl,"seta");
+
+/*** Map a signal to the frequency.
+@function mapf
+@tparam channel sig
+*/
+	lua_pushcfunction(s,l_mapf);
+	lua_setfield(s,tbl,"mapf");
+
+/*** Map a signal to the amplitude.
+@function mapa
+@tparam channel sig
+*/
+	lua_pushcfunction(s,l_mapa);
+	lua_setfield(s,tbl,"mapa");
+
+/*** Get the current oscillator value.
+@function sample
+@treturn number
+*/
+	lua_pushcfunction(s,l_sample);
+	lua_setfield(s,tbl,"sample");
+
+	lua_pushcfunction(s,l_out);
+	lua_setfield(s,tbl,MUTIL_OUTPUT_CHANNEL_FUNCTION);
+
+	luaL_newmetatable(s,OSCIL_TYPENAME);
+	int oscil_mt = lua_gettop(s);
+
+	lua_pushvalue(s,tbl);
+	lua_setfield(s,oscil_mt,"__index");
+
+/***
+@type wavetable
+*/
+	lua_newtable(s);
+	int wt_tbl = lua_absindex(s,lua_gettop(s));
+
+	lua_pushvalue(s,wt_tbl);
+	lua_setfield(s,tbl,"wavetable");
+
+	lua_pushcfunction(s,l_const);
+	lua_setfield(s,wt_tbl,"const");
+
+/*** Sine wave.
+@static
+@function wavetable.sin
+@treturn wavetable
+*/
+	lua_pushcfunction(s,l_sin);
+	lua_setfield(s,wt_tbl,"sin");
+
+/*** Saw wave.
+@static
+@function wavetable.saw
+@treturn wavetable
+*/
+	lua_pushcfunction(s,l_saw);
+	lua_setfield(s,wt_tbl,"saw");
+
+/*** Square wave.
+@static
+@function wavetable.square
+@treturn wavetable
+*/
+	lua_pushcfunction(s,l_square);
+	lua_setfield(s,wt_tbl,"square");
+
+	lua_pushcfunction(s,l_shift);
+	lua_setfield(s,wt_tbl,"shift");
+
+	lua_pushcfunction(s,l_scale);
+	lua_setfield(s,wt_tbl,"scale");
+
+	luaL_newmetatable(s,WAVETABLE_TYPENAME);
+	int wt_mt = lua_gettop(s);
+
+	lua_pushvalue(s,wt_tbl);
+	lua_setfield(s,wt_mt,"__index");
+
+	lua_pushcfunction(s,l_add);
+	lua_setfield(s,wt_mt,"__add");
+
+	lua_settop(s,tbl);
+	return 1;
+}