Added lua scripting capabilities

- basic configuration is now done via a lua script
- all the animation is generated by a lua script (see pulsetunnel.lua
  and vumeter.lua for examples)
- basic calculations (FFT, RMS) are done in C and accessible on demand
  from the lua scripts

Makefile

@@ -1,10 +1,13 @@
+LUA_CFLAGS=$(shell pkg-config --cflags lua)
+LUA_LIBS=$(shell pkg-config --libs lua)
+
 CC=gcc
-CFLAGS+=-O3 -Wall -march=native -pedantic -std=c99 -D_POSIX_C_SOURCE=20120607L -D_XOPEN_SOURCE
+CFLAGS+=-O2 -Wall -march=native -pedantic -std=c99 -D_POSIX_C_SOURCE=20120607L -D_XOPEN_SOURCE $(LUA_CFLAGS)
-LIBS=-lm -lpthread -lrt
+LIBS=-lm -lpthread -lrt $(LUA_LIBS)
 
 TARGET=musiclight2
-SOURCE=main.c fft.c utils.c ws2801.c
+SOURCE=main.c fft.c utils.c ws2801.c lua_utils.c lua_wrappers.c
-DEPS=config.h fft.h utils.h ws2801.h
+DEPS=config.h fft.h utils.h ws2801.h lua_utils.h lua_wrappers.h
 
 OBJ=$(patsubst %.c, %.o, $(SOURCE))
 

config.h

@@ -30,9 +30,6 @@
 // update rate for the led strip (in seconds)
 #define LED_INTERVAL 0.03
 
-// number of modules in LED strip
-#define NUM_MODULES 20
-
 // frequency ranges for the base colors
 #define RED_MIN_FREQ 0
 #define RED_MAX_FREQ 400
@@ -43,10 +40,6 @@
 
 #define COLOR_MAX_REDUCTION_FACTOR 0.9998
 
-#define CENTER_MODULE 10
-
-#define GAMMA 2.0
-
 // sample data types
 typedef int16_t sample;
 typedef int64_t sample_sum;

config.lua

@@ -0,0 +1,7 @@
+WS2801_HOST = "192.168.23.222"
+WS2801_PORT = 2703
+
+NUM_MODULES = 20
+CENTER_MODULE = 10
+
+GAMMA = 2.0

lua_utils.c

@@ -0,0 +1,73 @@
+/*
+ * vim: sw=2 ts=2 expandtab
+ *
+ * THE PIZZA-WARE LICENSE" (derived from "THE BEER-WARE LICENCE"):
+ * <cfr34k@tkolb.de> wrote this file. As long as you retain this notice you can
+ * do whatever you want with this stuff. If we meet some day, and you think
+ * this stuff is worth it, you can buy me a pizza in return. - Thomas Kolb
+ */
+
+#include <lua.h>
+#include <lualib.h>
+#include <lauxlib.h>
+
+#include "lua_utils.h"
+
+void lua_showerror(lua_State *L, const char *msg) {
+  fprintf(stderr, "\nLUA ERROR:\n  %s: %s\n\n",
+      msg, lua_tostring(L, -1));
+}
+
+void lua_pushdoublearray(lua_State *L, double *numbers, size_t len) {
+  size_t i;
+
+  // create an empty table
+  lua_createtable(L, len, 0);
+
+  for(i = 0; i < len; i++) {
+    // push key and value
+    lua_pushnumber(L, i+1); // lua arrays count from 1
+    lua_pushnumber(L, numbers[i]);
+
+    // store the values in the table
+    lua_settable(L, -3);
+  }
+}
+
+void lua_pushsamplearray(lua_State *L, sample *numbers, size_t len) {
+  size_t i;
+
+  // create an empty table
+  lua_createtable(L, len, 0);
+
+  for(i = 0; i < len; i++) {
+    // push key and value
+    lua_pushnumber(L, i+1); // lua arrays count from 1
+    lua_pushnumber(L, numbers[i]);
+
+    // store the values in the table
+    lua_settable(L, -3);
+  }
+}
+
+void lua_readdoublearray(lua_State *L, double *numbers, size_t len) {
+  size_t k;
+  double v;
+
+  // go to the top of the stack
+  lua_pushnil(L);
+
+  while(lua_next(L, -2)) {
+    v = lua_tonumber(L, -1);
+    lua_pop(L, 1);
+    k = lua_tointeger(L, -1);
+
+    if(k > len || k < 1) {
+      fprintf(stderr, "Warning: Lua index (%u) is out of C array range (%u)!\n", k, len);
+    } else {
+      numbers[k-1] = v;
+    }
+  }
+
+  lua_pop(L, 1);
+}

lua_utils.h

@@ -0,0 +1,20 @@
+/*
+ * vim: sw=2 ts=2 expandtab
+ *
+ * THE PIZZA-WARE LICENSE" (derived from "THE BEER-WARE LICENCE"):
+ * <cfr34k@tkolb.de> wrote this file. As long as you retain this notice you can
+ * do whatever you want with this stuff. If we meet some day, and you think
+ * this stuff is worth it, you can buy me a pizza in return. - Thomas Kolb
+ */
+
+#ifndef LUA_UTILS_H
+#define LUA_UTILS_H
+
+#include "config.h"
+
+void lua_showerror(lua_State *L, const char *msg);
+void lua_pushdoublearray(lua_State *L, double *numbers, size_t len);
+void lua_pushsamplearray(lua_State *L, sample *numbers, size_t len);
+void lua_readdoublearray(lua_State *L, double *numbers, size_t len);
+
+#endif // LUA_UTILS_H

lua_wrappers.c

@@ -0,0 +1,73 @@
+/*
+ * vim: sw=2 ts=2 expandtab
+ *
+ * THE PIZZA-WARE LICENSE" (derived from "THE BEER-WARE LICENCE"):
+ * <cfr34k@tkolb.de> wrote this file. As long as you retain this notice you can
+ * do whatever you want with this stuff. If we meet some day, and you think
+ * this stuff is worth it, you can buy me a pizza in return. - Thomas Kolb
+ */
+
+#include <semaphore.h>
+
+#include <lua.h>
+#include <lualib.h>
+#include <lauxlib.h>
+
+#include "fft.h"
+
+#include "config.h"
+
+#include "lua_utils.h"
+#include "lua_wrappers.h"
+
+extern sem_t  fftSemaphore;
+extern double fft[BLOCK_LEN];
+extern sample signal[BLOCK_LEN];
+extern double rms;
+
+static int l_get_energy_in_band(lua_State *L) {
+  int lowerFreq, higherFreq;
+
+  luaL_checktype(L, 1, LUA_TNUMBER);
+  lowerFreq = lua_tointeger(L, 1);
+
+  luaL_checktype(L, 2, LUA_TNUMBER);
+  higherFreq = lua_tointeger(L, 2);
+
+  sem_wait(&fftSemaphore);
+  lua_pushnumber(L, get_energy_in_band(fft, lowerFreq, higherFreq));
+  sem_post(&fftSemaphore);
+
+  return 1; // number of arguments
+}
+
+static int l_get_fft(lua_State *L) {
+  sem_wait(&fftSemaphore);
+  lua_pushdoublearray(L, fft, BLOCK_LEN);
+  sem_post(&fftSemaphore);
+
+  return 1; // number of return values
+}
+
+static int l_get_signal(lua_State *L) {
+  sem_wait(&fftSemaphore);
+  lua_pushsamplearray(L, signal, BLOCK_LEN);
+  sem_post(&fftSemaphore);
+
+  return 1; // number of return values
+}
+
+static int l_get_rms(lua_State *L) {
+  sem_wait(&fftSemaphore);
+  lua_pushnumber(L, rms);
+  sem_post(&fftSemaphore);
+
+  return 1; // number of return values
+}
+
+void lua_register_funcs(lua_State *L) {
+  lua_register(L, "get_energy_in_band", l_get_energy_in_band);
+  lua_register(L, "get_fft", l_get_fft);
+  lua_register(L, "get_signal", l_get_signal);
+  lua_register(L, "get_rms", l_get_rms);
+}

lua_wrappers.h

@@ -0,0 +1,21 @@
+/*
+ * vim: sw=2 ts=2 expandtab
+ *
+ * THE PIZZA-WARE LICENSE" (derived from "THE BEER-WARE LICENCE"):
+ * <cfr34k@tkolb.de> wrote this file. As long as you retain this notice you can
+ * do whatever you want with this stuff. If we meet some day, and you think
+ * this stuff is worth it, you can buy me a pizza in return. - Thomas Kolb
+ */
+
+#ifndef LUA_WRAPPERS_H
+#define LUA_WRAPPERS_H
+
+void lua_register_funcs(lua_State *L);
+
+/*
+static int l_get_energy_in_band(lua_State *L);
+static int l_get_fft(lua_State *L);
+static int l_get_signal(lua_State *L);
+*/
+
+#endif // LUA_WRAPPERS_H

main.c

@@ -14,6 +14,14 @@
 #include <math.h>
 #include <string.h>
 #include <stdint.h>
+#include <malloc.h>
+
+#include <lua.h>
+#include <lualib.h>
+#include <lauxlib.h>
+
+#include "lua_utils.h"
+#include "lua_wrappers.h"
 
 #include "fft.h"
 #include "utils.h"
@@ -27,12 +35,9 @@
 // Number of new samples put into the buffer each frame
 #define READ_SAMPLES (BLOCK_LEN / BUFFER_PARTS)
 
-#define COLORBUF_SIZE (2*(NUM_MODULES+1))
-#define CENTER_POS (2*CENTER_MODULE)
-
 double fft[BLOCK_LEN];
+sample signal[BLOCK_LEN];
 double rms;
-double redEnergy, greenEnergy, blueEnergy;
 double lastUpdateTime = 0;
 
 sem_t  fftSemaphore;
@@ -72,7 +77,7 @@ void* fft_thread(void *param) {
 
     tmpRMS = 0;
     for(i = 0; i < BLOCK_LEN; i++) {
-      tmpRMS += block[i]*block[i];
+      tmpRMS += buffer[i]*buffer[i];
     }
     tmpRMS = sqrt(tmpRMS/BLOCK_LEN);
 
@@ -80,10 +85,8 @@ void* fft_thread(void *param) {
     sem_wait(&fftSemaphore);
 
     memcpy(fft, tmpFFT, sizeof(fft));
+    memcpy(signal, buffer, sizeof(signal));
     rms = tmpRMS;
-    redEnergy = get_energy_in_band(fft, RED_MIN_FREQ, RED_MAX_FREQ);
-    greenEnergy = get_energy_in_band(fft, GREEN_MIN_FREQ, GREEN_MAX_FREQ);
-    blueEnergy = get_energy_in_band(fft, BLUE_MIN_FREQ, BLUE_MAX_FREQ);
 
 		curTime = get_hires_time();
     lastUpdateTime = curTime;
@@ -113,64 +116,97 @@ void* fft_thread(void *param) {
 	return NULL;
 }
 
-double gamma_correct(double d) {
+double gamma_correct(double d, double gamma) {
-  return pow(d, GAMMA);
+  return pow(d, gamma);
-}
-
-void text_bar(double fill) {
-  int fillCnt = 10 * fill;
-  int i;
-
-  for(i = 0; i < fillCnt; i++) {
-    printf("|");
-  }
-
-  for(; i < 10; i++) {
-    printf("-");
-  }
-}
-
-double weighted_avg(uint8_t colorBuf[COLORBUF_SIZE][3], int channel, int centerPos) {
-  return 0.20 * colorBuf[centerPos - 1][channel] +
-         0.60 * colorBuf[centerPos][channel] +
-         0.20 * colorBuf[centerPos + 1][channel];
-}
-
-void show_status(double curRed, double maxRed, double curGreen, double maxGreen, double curBlue, double maxBlue) {
-  printf("\r");
-
-  printf("[\033[31m");
-  text_bar(curRed / maxRed);
-  printf("\033[0m] ");
-  printf("\033[1;31m%7.2e\033[0m ", maxRed / (RED_MAX_FREQ - RED_MIN_FREQ));
-
-  printf("[\033[32m");
-  text_bar(curGreen / maxGreen);
-  printf("\033[0m] ");
-  printf("\033[1;32m%7.2e\033[0m ", maxGreen / (GREEN_MAX_FREQ - GREEN_MIN_FREQ));
-
-  printf("[\033[34m");
-  text_bar(curBlue / maxBlue);
-  printf("\033[0m] ");
-  printf("\033[1;34m%7.2e\033[0m ", maxBlue / (BLUE_MAX_FREQ - BLUE_MIN_FREQ));
-
-  fflush(stdout);
 }
 
 int main(int argc, char **argv) {
   double nextFrame = get_hires_time() + LED_INTERVAL;
 
-	int i, j;
+	int i;
 	pthread_t fftThread;
 
   int active = 1;
 
-  uint8_t colorBuf[COLORBUF_SIZE][3];
+  double *red;
+  double *green;
+  double *blue;
 
-  double curRedEnergy, curGreenEnergy, curBlueEnergy;
+  int useFading, fadeStep;
-  double maxRedEnergy = 1, maxGreenEnergy = 1, maxBlueEnergy = 1;
 
-  memset(colorBuf, 0, sizeof(colorBuf));
+  if(argc < 2) {
+    fprintf(stderr, "LUA script file must be given as command line argument!\n");
+    return 1;
+  }
+
+  // initialize lua
+  lua_State *L = lua_open();
+
+  // load the lua libraries
+  luaL_openlibs(L);
+
+  // register local functions
+  lua_register_funcs(L);
+
+  // load the configuration from "config.lua"
+  if(luaL_dofile(L, "config.lua")) {
+    lua_showerror(L, "luaL_dofile(config.lua) failed.");
+    return 1;
+  }
+
+  lua_getglobal(L, "WS2801_HOST");
+  if(!lua_isstring(L, -1)) return 2;
+  const char *host = lua_tostring(L, -1);
+
+  lua_getglobal(L, "WS2801_PORT");
+  if(!lua_isnumber(L, -1)) return 2;
+  unsigned short port = lua_tointeger(L, -1);
+
+  lua_getglobal(L, "GAMMA");
+  if(!lua_isnumber(L, -1)) return 2;
+  double gamma = lua_tonumber(L, -1);
+
+  lua_getglobal(L, "NUM_MODULES");
+  if(!lua_isnumber(L, -1)) return 2;
+  int num_modules = lua_tointeger(L, -1);
+
+  lua_getglobal(L, "CENTER_MODULE");
+  if(!lua_isnumber(L, -1)) return 2;
+  int center_module = lua_tointeger(L, -1);
+
+  // allocate arrays
+  red = malloc(num_modules * sizeof(double));
+  green = malloc(num_modules * sizeof(double));
+  blue = malloc(num_modules * sizeof(double));
+
+  // load and initialize the script
+  if(luaL_loadfile(L, argv[1])) {
+    lua_showerror(L, "luaL_loadfile(cmdline_argument) failed.");
+  }
+
+  // priming call: read the lua file to make functions known
+  if(lua_pcall(L, 0, 0, 0)) {
+    lua_showerror(L, "lua_pcall failed.");
+  }
+
+  // call the init function
+  lua_getglobal(L, "init");
+  lua_pushnumber(L, num_modules);
+  lua_pushnumber(L, center_module);
+  if(lua_pcall(L, 2, 1, 0)) {
+    lua_showerror(L, "lua_pcall(init) failed.");
+  }
+
+  fadeStep = lua_tointeger(L, -1);
+  useFading = fadeStep > 0;
+  if(useFading) {
+    ws2801_set_fadestep(fadeStep);
+    printf("Fading enabled with fadestep %i.\n", fadeStep);
+  }
+
+  // initialize the WS2801 library
+  printf("Connecting to %s:%i\n", host, port);
+  ws2801_init(host, port);
 
 	// create semaphores
 	sem_init(&fftSemaphore, 0, 1);
@@ -178,68 +214,41 @@ int main(int argc, char **argv) {
 	// run the fft thread
 	pthread_create(&fftThread, NULL, fft_thread, NULL);
 
-  ws2801_init(HOST, PORT);
-
 	while(running) {
-    for(i = COLORBUF_SIZE-1; i >= 0; i--) {
-      int pos = CENTER_POS + i;
-      if(pos < COLORBUF_SIZE-1) {
-        for(j = 0; j < 3; j++) {
-          colorBuf[pos][j] = colorBuf[pos - 1][j];
-        }
-      }
-
-      pos = CENTER_POS - i;
-      if(pos >= 0) {
-        for(j = 0; j < 3; j++) {
-          colorBuf[pos][j] = colorBuf[pos + 1][j];
-        }
-      }
-    }
-
     if(active) {
-      sem_wait(&fftSemaphore);
+      // call the periodic() function from LUA
-      curRedEnergy = redEnergy;
+      lua_getglobal(L, "periodic");
-      curGreenEnergy = greenEnergy;
+      if(lua_pcall(L, 0, 3, 0)) { // no arguments, 3 return values
-      curBlueEnergy = blueEnergy;
+        lua_showerror(L, "lua_pcall(periodic) failed.");
-      sem_post(&fftSemaphore);
-
-      maxRedEnergy *= COLOR_MAX_REDUCTION_FACTOR;
-      if(curRedEnergy > maxRedEnergy) {
-        maxRedEnergy = curRedEnergy;
       }
 
-      maxGreenEnergy *= COLOR_MAX_REDUCTION_FACTOR;
+      // read the return values (reverse order, as lua uses a stack)
-      if(curGreenEnergy > maxGreenEnergy) {
+      lua_readdoublearray(L, blue, num_modules);
-        maxGreenEnergy = curGreenEnergy;
+      lua_readdoublearray(L, green, num_modules);
+      lua_readdoublearray(L, red, num_modules);
+
+      if(useFading) {
+        for(i = 0; i < num_modules; i++) {
+          ws2801_fade_color(i,
+              255 * gamma_correct(red[i], gamma),
+              255 * gamma_correct(green[i], gamma),
+              255 * gamma_correct(blue[i], gamma));
+        }
+        ws2801_commit();
+      } else {
+        for(i = 0; i < num_modules; i++) {
+          ws2801_set_color(i,
+              255 * gamma_correct(red[i], gamma),
+              255 * gamma_correct(green[i], gamma),
+              255 * gamma_correct(blue[i], gamma));
+        }
+        ws2801_commit();
       }
 
-      maxBlueEnergy *= COLOR_MAX_REDUCTION_FACTOR;
-      if(curBlueEnergy > maxBlueEnergy) {
-        maxBlueEnergy = curBlueEnergy;
-      }
-
-      colorBuf[CENTER_POS][0] = 255 * gamma_correct(curRedEnergy / maxRedEnergy);
-      colorBuf[CENTER_POS][1] = 255 * gamma_correct(curGreenEnergy / maxGreenEnergy);
-      colorBuf[CENTER_POS][2] = 255 * gamma_correct(curBlueEnergy / maxBlueEnergy);
-
-      /*
-      show_status(curRedEnergy, maxRedEnergy, curGreenEnergy, maxGreenEnergy,
-          curBlueEnergy, maxBlueEnergy);
-      */
-
-      for(i = 0; i < NUM_MODULES; i++) {
-        ws2801_set_color(i,
-            weighted_avg(colorBuf, 0, 2 * i + 1),
-            weighted_avg(colorBuf, 1, 2 * i + 1),
-            weighted_avg(colorBuf, 2, 2 * i + 1));
-      }
-      ws2801_commit();
-
       if(lastUpdateTime < nextFrame - 1) {
         printf("Idle for 1 second -> stopping updates.\n");
 
-        for(i = 0; i < NUM_MODULES; i++) {
+        for(i = 0; i < num_modules; i++) {
           ws2801_fade_color(i, 20, 20, 20);
         }
         ws2801_commit();
@@ -257,7 +266,14 @@ int main(int argc, char **argv) {
 
   ws2801_shutdown();
 
+  // free arrays
+  free(red);
+  free(green);
+  free(blue);
+
 	pthread_join(fftThread, NULL);
 
+  lua_close(L);
+
 	return 0;
 }

pulsetunnel.lua

@@ -0,0 +1,70 @@
+COOLDOWN_FACTOR = 0.9998
+
+num_modules = 20
+center_module = 10
+
+-- maximum energy values for each band
+maxRedEnergy = 1
+maxGreenEnergy = 1
+maxBlueEnergy = 1
+
+-- output color buffers
+red = {}
+green = {}
+blue = {}
+
+function periodic()
+  local redEnergy = get_energy_in_band(0, 400);
+  local greenEnergy = get_energy_in_band(400, 4000);
+  local blueEnergy = get_energy_in_band(4000, 22000);
+
+  maxRedEnergy = maxRedEnergy * COOLDOWN_FACTOR
+  if redEnergy > maxRedEnergy then
+    maxRedEnergy = redEnergy
+  end
+
+  maxGreenEnergy = maxGreenEnergy * COOLDOWN_FACTOR
+  if greenEnergy > maxGreenEnergy then
+    maxGreenEnergy = greenEnergy
+  end
+
+  maxBlueEnergy = maxBlueEnergy * COOLDOWN_FACTOR
+  if blueEnergy > maxBlueEnergy then
+    maxBlueEnergy = blueEnergy
+  end
+
+  -- move the color buffers on by one in each direction
+  for i = 2,center_module,1 do
+    red[i-1]   = red[i]
+    green[i-1] = green[i]
+    blue[i-1]  = blue[i]
+  end
+
+  for i = num_modules-1,center_module,-1 do
+    red[i+1]   = red[i]
+    green[i+1] = green[i]
+    blue[i+1]  = blue[i]
+  end
+
+  -- set the new value for the center module
+  red[center_module] = redEnergy / maxRedEnergy
+  green[center_module] = greenEnergy / maxGreenEnergy
+  blue[center_module] = blueEnergy / maxBlueEnergy
+
+  -- return the 3 color arrays
+  return red, green, blue
+end
+
+function init(nmod, cmod)
+  num_modules = nmod
+  center_module = cmod
+
+  for i = 1,nmod do
+    red[i] = 0
+    green[i] = 0
+    blue[i] = 0
+  end
+
+  -- don't use fading
+  return 0
+end

run_alsa.sh

@@ -1,3 +1,3 @@
 #!/bin/sh
 
-arecord -c 1 -f s16 -r 22050 | ./rtfft
+arecord -c 1 -f s16 -r 22050 | ./musiclight2 $*

run_mpd.sh

@@ -1,4 +1,4 @@
 #!/bin/sh
 
 #dd if=/tmp/mpd.fifo bs=1024 | ./musiclight2
-./musiclight2 < /tmp/mpd.fifo
+./musiclight2 $* < /tmp/mpd.fifo

run_pa.sh

@@ -5,12 +5,12 @@
 case $1 in
   mic)
     #mikro
-    parec -d "alsa_input.pci-0000_00_1b.0.analog-stereo" --raw --rate=44100 --channels=1 --format=s16 | ./musiclight2
+    parec -d "alsa_input.pci-0000_00_1b.0.analog-stereo" --raw --rate=44100 --channels=1 --format=s16 | ./musiclight2 $*
     ;;
 
   *)
     # soundkarte
-    parec -d "alsa_output.pci-0000_00_1b.0.analog-stereo.monitor" --raw --rate=44100 --channels=1 --format=s16 | ./musiclight2
+    parec -d "alsa_output.pci-0000_00_1b.0.analog-stereo.monitor" --raw --rate=44100 --channels=1 --format=s16 | ./musiclight2 $*
     ;;
 esac
 

run_remote.sh

@@ -1,3 +1,3 @@
 #!/bin/sh
 
-nc -l -p 12345 | ./musiclight2
+nc -l -p 12345 | ./musiclight2 $*

vumeter.lua

@@ -0,0 +1,85 @@
+COOLDOWN_FACTOR = 0.9998
+FACTOR = 0.2
+
+num_modules = 20
+center_module = 10
+
+-- maximum energy values for each band
+maxRedEnergy = 1
+maxGreenEnergy = 1
+maxBlueEnergy = 1
+maxRMS = 1
+
+-- output color buffers
+red = {}
+green = {}
+blue = {}
+
+function periodic()
+  local redEnergy = get_energy_in_band(0, 400);
+  local greenEnergy = get_energy_in_band(400, 4000);
+  local blueEnergy = get_energy_in_band(4000, 22000);
+  local rms = get_rms();
+
+  maxRedEnergy = maxRedEnergy * COOLDOWN_FACTOR
+  if redEnergy > maxRedEnergy then
+    maxRedEnergy = redEnergy
+  end
+
+  maxGreenEnergy = maxGreenEnergy * COOLDOWN_FACTOR
+  if greenEnergy > maxGreenEnergy then
+    maxGreenEnergy = greenEnergy
+  end
+
+  maxBlueEnergy = maxBlueEnergy * COOLDOWN_FACTOR
+  if blueEnergy > maxBlueEnergy then
+    maxBlueEnergy = blueEnergy
+  end
+
+  maxRMS = maxRMS * COOLDOWN_FACTOR
+  if rms > maxRMS then
+    maxRMS = rms
+  end
+
+  local brightness = rms / maxRMS
+
+  for i = 1,num_modules do
+    if i <= num_modules * redEnergy / maxRedEnergy then
+      redTarget = brightness
+    else
+      redTarget = 0
+    end
+    red[i] = (1 - FACTOR) * red[i] + FACTOR * redTarget;
+
+    if i <= num_modules * greenEnergy / maxGreenEnergy then
+      greenTarget = brightness
+    else
+      greenTarget = 0
+    end
+    green[i] = (1 - FACTOR) * green[i] + FACTOR * greenTarget;
+
+    if i <= num_modules * blueEnergy / maxBlueEnergy then
+      blueTarget = brightness
+    else
+      blueTarget = 0
+    end
+    blue[i] = (1 - FACTOR) * blue[i] + FACTOR * blueTarget;
+  end
+
+  -- return the 3 color arrays
+  return red, green, blue
+end
+
+function init(nmod, cmod)
+  num_modules = nmod
+  center_module = cmod
+
+  for i = 1,nmod do
+    red[i] = 0
+    green[i] = 0
+    blue[i] = 0
+  end
+
+  -- fadestep (0 = no fading)
+  return 0
+end

ws2801.c

@@ -32,7 +32,7 @@ struct WS2801Packet packetQueue[50];
 int queueIndex = 0;
 
 // creates the socket needed for steering the LED strip
-int ws2801_init(char *host, unsigned short port) {
+int ws2801_init(const char *host, unsigned short port) {
   struct addrinfo  hints;
   struct addrinfo *result;
   char portstr[6];

ws2801.h

@@ -10,7 +10,7 @@
 #ifndef WS2801_H
 #define WS2801_H
 
-int ws2801_init(char *host, unsigned short port);
+int ws2801_init(const char *host, unsigned short port);
 void ws2801_set_color(uint8_t module, uint8_t r, uint8_t g, uint8_t b);
 void ws2801_fade_color(uint8_t module, uint8_t r, uint8_t g, uint8_t b);
 void ws2801_add_color(uint8_t module, uint8_t r, uint8_t g, uint8_t b);