ws2812: implement brightness/dimming for ws2812,keep buffer while providing rgb

brightness may between 0 and 1 and will be applied with the next ws2812.write
ws2812.write now takes R,G,B instead of grb (was undocumumented before) by
allocating a transfer buffer and freeing it afterwards.

ws2812.writergb now becomes obsolete with it but currently remains in the
module.

README.md

@@ -440,12 +440,18 @@ In contrast to the source code based inclusion of XBMs into u8glib, it's require
 
 ####Control a WS2812 based light strip
 ```lua
+  
 	-- set the color of one LED on GPIO2 to red
-	ws2812.writergb(4, string.char(255, 0, 0))
+	ws2812.write(4, string.char(255, 0, 0))
-	-- set the color of 10 LEDs on GPIO0 to blue
+  -- set the brightness to 50%
-	ws2812.writergb(3, string.char(0, 0, 255):rep(10))
+  ws2812.set_brightness(0.5)
-	-- first LED green, second LED white
+	-- set the color of 10 LEDs on GPIO0 to blue with half brightness
-	ws2812.writergb(4, string.char(0, 255, 0, 255, 255, 255))
+	ws2812.write(3, string.char(0, 0, 255):rep(10))
+  --returns the current brightness
+  print(ws2812.brightness())
+  0.5
+	-- first LED green, second LED white at half brightness
+	ws2812.write(4, string.char(0, 255, 0, 255, 255, 255))
 ```
 
 ####coap client and server

app/modules/ws2812.c

@@ -5,6 +5,15 @@
 #include "lrotable.h"
 #include "c_stdlib.h"
 #include "c_string.h"
+#include "c_math.h"
+
+#include "c_stdio.h"
+#include "c_stdlib.h"
+#include "c_stdarg.h"
+#include "c_string.h"
+
+#include "strbuf.h"
+
 /**
  * All this code is mostly from http://www.esp8266.com/viewtopic.php?f=21&t=1143&sid=a620a377672cfe9f666d672398415fcb
  * from user Markus Gritsch.
@@ -28,89 +37,128 @@ static void ICACHE_FLASH_ATTR __attribute__((optimize("O2"))) send_ws_1(uint8_t
   i = 6; while (i--) GPIO_REG_WRITE(GPIO_OUT_W1TC_ADDRESS, 1 << gpio);
 }
 
-// Lua: ws2812.writergb(pin, "string")
+// brightness may be between 0 and 1
-// Byte triples in the string are interpreted as R G B values and sent to the hardware as G R B.
+#define MAX_BRIGHTNESS 1
-// WARNING: this function scrambles the input buffer :
-//    a = string.char(255,0,128)
-//    ws212.writergb(3,a)
-//    =a.byte() 
-//    (0,255,128)
 
-// ws2812.writergb(4, string.char(255, 0, 0)) uses GPIO2 and sets the first LED red.
+// Brightness is a floating-point number which will be multiplied before
-// ws2812.writergb(3, string.char(0, 0, 255):rep(10)) uses GPIO0 and sets ten LEDs blue.
+// setting an LED
-// ws2812.writergb(4, string.char(0, 255, 0, 255, 255, 255)) first LED green, second LED white.
+static lua_Number brightness = MAX_BRIGHTNESS;
-static int ICACHE_FLASH_ATTR ws2812_writergb(lua_State* L)
-{
-  const uint8_t pin = luaL_checkinteger(L, 1);
-  size_t length;
-  const char *rgb = luaL_checklstring(L, 2, &length);
-  // dont modify lua-internal lstring - make a copy instead
-  char *buffer = (char *)c_malloc(length);
-  c_memcpy(buffer, rgb, length);
 
-  // Initialize the output pin:
-  platform_gpio_mode(pin, PLATFORM_GPIO_OUTPUT, PLATFORM_GPIO_FLOAT);
-  platform_gpio_write(pin, 0);
-
-  // Ignore incomplete Byte triples at the end of buffer:
-  length -= length % 3;
-
-  // Rearrange R G B values to G R B order needed by WS2812 LEDs:
-  size_t i;
-  for (i = 0; i < length; i += 3) {
-    const char r = buffer[i];
-    const char g = buffer[i + 1];
-    buffer[i] = g;
-    buffer[i + 1] = r;
-  }
-
-  // Do not remove these:
-  os_delay_us(1);
-  os_delay_us(1);
-
-  // Send the buffer:
-  os_intr_lock();
-  for (i = 0; i < length; i++) {
-    uint8_t mask = 0x80;
-    while (mask) {
-      (buffer[i] & mask) ? send_ws_1(pin_num[pin]) : send_ws_0(pin_num[pin]);
-      mask >>= 1;
-    }
-  }
-  os_intr_unlock();
-
-  c_free(buffer);
 
+// Lua: ws2812.set_brightness(brightness)
+// 
+// brightness must be between 0 and MAX_BRIGHTNESS
+static int ICACHE_FLASH_ATTR set_brightness(lua_State* L){
+  brightness = luaL_checknumber(L,1);
   return 0;
 }
 
+// Lua: brightness =ws2812.brightness()
+// returns the current brightness
+static int ICACHE_FLASH_ATTR get_brightness(lua_State* L){
+  lua_pushnumber(L,brightness);
+  return 1;
+}
+
+// Lua: R,G,B = ws2812.hsv2rgb(H,S,V)
+// H: Hue, S: Saturation, V: Value
+// R,G,B are on [0,255]
+//
+// H is given on [0, 1]. S and V are given on [0, 1].
+// This function does not corrupt your buffer
+//
+//  modified from Alvy Ray Smith's site:
+//  http://www.alvyray.com/Papers/hsv2rgb.htm
+static int ICACHE_FLASH_ATTR ws2812_hsv2rgb(lua_State* L) {
+  uint8_t i;
+  lua_Number m, n, f;
+  const lua_Number h = luaL_checknumber(L,1) * 6;
+  const lua_Number s = luaL_checknumber(L,2);
+  lua_Number v = luaL_checknumber(L,3);
+
+  // not very elegant way of dealing with out of range: return black
+  if ((s<0.0) || (s>1.0) || (v<0.0) || (v>1.0)) {
+    NODE_ERR("S or V out of range\n");
+    lua_pushnumber(L, 0); lua_pushnumber(L, 0); lua_pushnumber(L, 0);
+    return 3;
+  }
+  v = v * 255;
+  if ((h < 0.0) || (h > 6.0)) {
+    lua_pushnumber(L, v); lua_pushnumber(L, v); lua_pushnumber(L, v);
+    return 3;
+  }
+  i = floor(h);
+  f = h - i;
+  if ( !(i&1) ) {
+    f = 1 - f; // if i is even
+  }
+  m = v * (1 - s) ;
+  n = v * (1 - s * f) ;
+  switch (i) {
+  case 6:
+  case 0: // RETURN_RGB(v, n, m)
+    lua_pushnumber(L, v ); lua_pushnumber(L, n ); lua_pushnumber(L, m );break;
+  case 1: // RETURN_RGB(n, v, m) 
+    lua_pushnumber(L, n ); lua_pushnumber(L, v ); lua_pushnumber(L, m );break;
+  case 2:  // RETURN_RGB(m, v, n)
+    lua_pushnumber(L, m ); lua_pushnumber(L, v ); lua_pushnumber(L, n );break;
+  case 3:  // RETURN_RGB(m, n, v)
+    lua_pushnumber(L, m ); lua_pushnumber(L, n ); lua_pushnumber(L, v );break;
+  case 4:  // RETURN_RGB(n, m, v)
+    lua_pushnumber(L, n ); lua_pushnumber(L, m ); lua_pushnumber(L, v );break;
+  case 5:  // RETURN_RGB(v, m, n)
+    lua_pushnumber(L, v ); lua_pushnumber(L, m ); lua_pushnumber(L, n );break;
+  }
+  return 3;
+} 
+
 // Lua: ws2812.write(pin, "string")
-// Byte triples in the string are interpreted as G R B values.
+// Byte triples in the string are interpreted as R G B values.
-// This function does not corrupt your buffer.
+// This function does not corrupt your buffer
 //
 // ws2812.write(4, string.char(0, 255, 0)) uses GPIO2 and sets the first LED red.
 // ws2812.write(3, string.char(0, 0, 255):rep(10)) uses GPIO0 and sets ten LEDs blue.
 // ws2812.write(4, string.char(255, 0, 0, 255, 255, 255)) first LED green, second LED white.
-static int ICACHE_FLASH_ATTR ws2812_writegrb(lua_State* L) {
+static int ICACHE_FLASH_ATTR ws2812_writergb(lua_State* L) {
   const uint8_t pin = luaL_checkinteger(L, 1);
   size_t length;
   const char *buffer = luaL_checklstring(L, 2, &length);
+  // ignore incomplete byte triples for re-arranging
+  length -= length % 3;
+  char *transfer = (char*)c_malloc(length);
 
   platform_gpio_mode(pin, PLATFORM_GPIO_OUTPUT, PLATFORM_GPIO_FLOAT);
   platform_gpio_write(pin, 0);
-  os_delay_us(10);
+
+  // add brightness
+  size_t i;
+  for (i = 0; i < length; i ++) {
+    transfer[i] = buffer[i]*brightness;
+  }
+
+  // transfer from grb to rgb
+  for (i = 0; i < length; i += 3) {
+    const char r = transfer[i];
+    const char g = transfer[i + 1];
+    transfer[i] = g;
+    transfer[i + 1] = r;
+  }
+
+  os_delay_us(1);
+  os_delay_us(1);
 
   os_intr_lock();
-  const char * const end = buffer + length;
+  const char * const end = transfer + length;
-  while (buffer != end) {
+  while (transfer != end) {
     uint8_t mask = 0x80;
     while (mask) {
-      (*buffer & mask) ? send_ws_1(pin_num[pin]) : send_ws_0(pin_num[pin]);
+      ( *transfer & mask) ? send_ws_1(pin_num[pin]) : send_ws_0(pin_num[pin]);
       mask >>= 1;
     }
-    ++buffer;
+    ++transfer;
   }
   os_intr_unlock();
+  c_free(transfer-length);
 
   return 0;
 }
@@ -119,8 +167,10 @@ static int ICACHE_FLASH_ATTR ws2812_writegrb(lua_State* L) {
 #include "lrodefs.h"
 const LUA_REG_TYPE ws2812_map[] =
 {
-  { LSTRKEY( "writergb" ), LFUNCVAL( ws2812_writergb )},
+  { LSTRKEY( "set_brightness" ), LFUNCVAL( set_brightness )},
-  { LSTRKEY( "write" ), LFUNCVAL( ws2812_writegrb )},
+  { LSTRKEY( "brightness" ), LFUNCVAL( get_brightness )},
+  { LSTRKEY( "write" ), LFUNCVAL( ws2812_writergb )},
+  { LSTRKEY( "hsv2rgb" ), LFUNCVAL( ws2812_hsv2rgb )},
   { LNILKEY, LNILVAL}
 };