Out of memory tricks?

Posted on Thu 15th, October 2015

• #1

tve
I'm trying to load the BMP085 module onto an esp8266 with 800 JSvars and I'm getting an our of memory error when the IDE loads the module:
```
ERROR: Out of Memory!
WARNING: Unable to create string as not enough memory
```
I have 760 free JSvars after a reset:
```
>reset
=function () { [native code] }
>console.log("Mem:", process.memory());
Mem: { "free": 760, "usage": 40, "total": 800, "history": 26 }
```
Does it make sense that this is not enough for this small module? Are there any tricks I could employ?

• #2

allObjects

At this moment I do not have an Espruino board at hand to make a comparison of free space after reset and after requiring the module. I assume the modulle that is pulled from the Web is the minified version... http://www.espruino.com/modules/BMP085.min.js.

I pulled the code, did some formatting, and you might shrink it a bit more by dropping some of the debug stuff... also some shortening of member (value/function property) names can help.

function d(a){
	this.i2c=a;
	this.BME280_ADDRESS=118;
	this.debug=!1;
	96==this.read8(208)&&this.debug&&console.log("This chip is BME280");
	this.writeReg(242,1);
	this.writeReg(244,39);
	this.writeReg(245,160);
	this.readCoefficients()
}
d.prototype.concatU8=function(a,b){
	var c=new Uint8Array(a.length+b.length);
	c.set(a);
	c.set(b,a.length);
	return c
};
d.prototype.convS16=function(a,b){
	var c=(a<<8)+b;
	c&32768&&(c=-(c-1^65535));
	return c
};
d.prototype.writeReg=function(a,b){
	this.i2c.writeTo(this.BME280_ADDRESS,[a,b])
};
d.prototype.read8=function(a){
	this.i2c.writeTo(this.BME280_ADDRESS,a);
	return this.i2c.readFrom(this.BME280_ADDRESS,1)[0]
};
d.prototype.readCoefficients=function(){
	this.i2c.writeTo(this.BME280_ADDRESS,136);
	var a=this.i2c.readFrom(this.BME280_ADDRESS,24);
	this.i2c.writeTo(this.BME280_ADDRESS,161);
	a=this.concatU8(a,this.i2c.readFrom(this.BME280_ADDRESS,1));
	this.i2c.writeTo(this.BME280_ADDRESS,225);
	a=this.concatU8(a,this.i2c.readFrom(this.BME280_ADDRESS,7));
	this.dig_T1=a[1]<<8|a[0];
	this.dig_T2=this.convS16(a[3],a[2]);
	this.dig_T3=this.convS16(a[5],a[4]);
	this.dig_P1=a[7]<<8|a[6];
	this.dig_P2=this.convS16(a[9],a[8]);
	this.dig_P3=this.convS16(a[11],a[10]);
	this.dig_P4=this.convS16(a[13],a[12]);
	this.dig_P5=this.convS16(a[15],a[14]);
	this.dig_P6=this.convS16(a[17],a[16]);
	this.dig_P7=this.convS16(a[19],a[18]);
	this.dig_P8=this.convS16(a[21],a[20]);
	this.dig_P9=this.convS16(a[23],a[22]);
	this.dig_H1=a[24];
	this.dig_H2=this.convS16(a[26],a[25]);
	this.dig_H3=a[27];
	this.dig_H4=a[28]<<4|15&a[29];
	this.dig_H5=a[30]<<4|a[29]>>4&15;
	this.dig_H6=a[31]
};
d.prototype.readRawData=function(){this.i2c.writeTo(this.BME280_ADDRESS,247);
	var a=this.i2c.readFrom(this.BME280_ADDRESS,8);
	this.debug&&(console.log("d0: "+a[0]),console.log("d1: "+a[1])
		,console.log("d2: "+a[2]),console.log("d3: "+a[3])
		,console.log("d4: "+a[4]),console.log("d5: "+a[5])
		,console.log("d6: "+a[6]),console.log("d7: "+a[7]));
	this.pres_raw=a[0]<<12|a[1]<<4|a[2]>>4;
	this.temp_raw=a[3]<<12|a[4]<<4|a[5]>>4;
	this.hum_raw=a[6]<<8|a[7]
};
d.prototype.calibration_T=function(a){
	var b;
	b=(a/16384-this.dig_T1/1024)*this.dig_T2;
	a=(a/131072-this.dig_T1/8192)*(a/131072-this.dig_T1/8192)*this.dig_T3;
	this.t_fine=b+a;
	return(b+a)/5120*100
};
d.prototype.calibration_P=function(a){
	this.debug&&(console.log("T1: "+this.dig_T1),console.log("T2: "+this.dig_T2)
		,console.log("T3: "+this.dig_T3),console.log("H1: "+this.dig_H1)
		,console.log("H2: "+this.dig_H2),console.log("H3: "+this.dig_H3)
		,console.log("H4: "+this.dig_H4),console.log("H5: "+this.dig_H5)
		,console.log("H6: "+this.dig_H6),console.log("P1: "+this.dig_P1)
		,console.log("P2: "+this.dig_P2),console.log("P3: "+this.dig_P3)
		,console.log("P4: "+this.dig_P4),console.log("P5: "+this.dig_P5)
		,console.log("P6: "+this.dig_P6),console.log("P7: "+this.dig_P7)
		,console.log("P8: "+this.dig_P8),console.log("P9: "+this.dig_P9));
	var b,c;
	b=this.t_fine/2-64E3;
	c=b*b*this.dig_P6/32768;
	c+=b*this.dig_P5*2;
	c=c/4+65536*this.dig_P4;
	b=(this.dig_P3*b*b/524288+this.dig_P2*b)/524288;
	b=(1+b/32768)*this.dig_P1;
	if(0===b)return 0;
	a=6250*(1048576-a-c/4096)/b;
	b=this.dig_P9*a*a/2147483648;
	c=a*this.dig_P8/32768;
	return a+=(b+c+this.dig_P7)/16
};
d.prototype.calibration_H=function(a){var b;
	b=this.t_fine-76800;
	b=((a<<14)-(this.dig_H4<<20)-this.dig_H5*b+16384>>15)
		*((((b*this.dig_H6>>10)*((b*this.dig_H3>>11)+32768)>>10)+2097152)*this.dig_H2+8192>>14);
	b-=((b>>15)*(b>>15)>>7)*this.dig_H1>>4;
	b=0>b?0:b;
	return(419430400<b?419430400:b)>>12
};
exports.connect=function(a){return new d(a)}

Here is what I manually did to it:

var d=function(a){
	this.i2c=a;
	this.addr=118;
	this.wR(242,1);
	this.wR(244,39);
	this.wR(245,160);
	this.rCs()
},p=d.prototype;
p.ccU8=function(a,b){
	var c=new Uint8Array(a.length+b.length);
	c.set(a);
	c.set(b,a.length);
	return c
};
p.cS16=function(a,b){
	var c=(a<<8)+b;
	c&32768&&(c=-(c-1^65535));
	return c
};
	p.wR=function(a,b){
	this.i2c.writeTo(this.addr,[a,b])
};
	p.r8=function(a){
	this.i2c.writeTo(this.addr,a);
	return this.i2c.readFrom(this.addr,1)[0]
};
p.rCs=function(){
	this.i2c.writeTo(this.addr,136);
	var a=this.i2c.readFrom(this.addr,24);
	this.i2c.writeTo(this.addr,161);
	a=this.ccU8(a,this.i2c.readFrom(this.addr,1));
	this.i2c.writeTo(this.addr,225);
	a=this.ccU8(a,this.i2c.readFrom(this.addr,7));
	this.dT1=a[1]<<8|a[0];
	this.dT2=this.cS16(a[3],a[2]);
	this.dT3=this.cS16(a[5],a[4]);
	this.dP1=a[7]<<8|a[6];
	this.dP2=this.cS16(a[9],a[8]);
	this.dP3=this.cS16(a[11],a[10]);
	this.dP4=this.cS16(a[13],a[12]);
	this.dP5=this.cS16(a[15],a[14]);
	this.dP6=this.cS16(a[17],a[16]);
	this.dP7=this.cS16(a[19],a[18]);
	this.dP8=this.cS16(a[21],a[20]);
	this.dP9=this.cS16(a[23],a[22]);
	this.dH1=a[24];
	this.dH2=this.cS16(a[26],a[25]);
	this.dH3=a[27];
	this.dH4=a[28]<<4|15&a[29];
	this.dH5=a[30]<<4|a[29]>>4&15;
	this.dH6=a[31]
};
	p.rRaw=function(){
	this.i2c.writeTo(this.addr,247);
	var a=this.i2c.readFrom(this.addr,8);
	this.pres_raw=a[0]<<12|a[1]<<4|a[2]>>4;
	this.temp_raw=a[3]<<12|a[4]<<4|a[5]>>4;
	this.hum_raw=a[6]<<8|a[7]
};
	p.calT=function(a){
	var b=(a/16384-this.dT1/1024)*this.dT2;
	a=(a/131072-this.dT1/8192)*(a/131072-this.dT1/8192)*this.dT3;
	this.t_fine=b+a;
	return(b+a)/5120*100
};
	p.calP=function(a){
	var b=this.t_fine/2-64E3,c=b*b*this.dP6/32768;
	c+=b*this.dP5*2;
	c=c/4+65536*this.dP4;
	b=(this.dP3*b*b/524288+this.dP2*b)/524288;
	b=(1+b/32768)*this.dP1;
	if(0===b)return 0;
	a=6250*(1048576-a-c/4096)/b;
	b=this.dP9*a*a/2147483648;
	c=a*this.dP8/32768;
	return a+=(b+c+this.dP7)/16
};
p.calH=function(a){
	var b=this.t_fine-76800;
	b=((a<<14)-(this.dH4<<20)-this.dH5*b+16384>>15)
		*((((b*this.dH6>>10)*((b*this.dH3>>11)+32768)>>10)+2097152)*this.dH2+8192>>14);
	b-=((b>>15)*(b>>15)>>7)*this.dH1>>4;
	b=0>b?0:b;
	return(419430400<b?419430400:b)>>12
};
exports.connect=function(a){return new d(a)}

And the attached file is the above code with tabs and new lines removed. I hope I did not mess with essentials... of course, it is a 'different' module... but constraints justify many means...

...reduction by 1374 bytes down to 2255 bytes... yes, looking at the code, it creates quite a lot of things...

1 Attachment

BME280m.js

• #3

tve

It gets minified. After loading it "only" uses ~420 JSvars, but during loading the string itself makes it all blow up.
The upload is:

Modules.addCached("BMP085","function c(b,a){this.i2c=b;this.oss=\"undefined\"!==typeof a?a:3;if(3<this.oss||0>this.oss)this.oss=3;var d=this.read8(208);if(85!=d)return console.log(\"Bad ID of: \"+d),null;this.readCoefficients()}c.prototype.read16=function(b){this.i2c.writeTo(119,b);b=this.i2c.readFrom(119,2);return b[0]<<8|b[1]};c.prototype.readS16=function(b){this.i2c.writeTo(119,b);b=this.i2c.readFrom(119,2);b=b[0]<<8|b[1];return 32767<=b?b-65536:b};c.prototype.read8=function(b){this.i2c.writeTo(119,b);return this.i2c.readFrom(119,\n1)[0]};c.prototype.readCoefficients=function(){this.ac1=this.readS16(170);this.ac2=this.readS16(172);this.ac3=this.readS16(174);this.ac4=this.read16(176);this.ac5=this.read16(178);this.ac6=this.read16(180);this.b1=this.readS16(182);this.b2=this.readS16(184);this.mb=this.readS16(186);this.mc=this.readS16(188);this.md=this.readS16(190)};c.prototype.readRawTemperature=function(b){this.i2c.writeTo(119,[244,46]);var a=this;setTimeout(function(){b(a.read16(246))},5)};c.prototype.readRawPressure=function(b){this.i2c.writeTo(119,\n[244,52+(this.oss<<6)]);var a,d=this;switch(this.oss){case 0:a=5;break;case 1:a=8;break;case 2:a=14;break;case 3:a=26}setTimeout(function(){var a=d.read8(246),c=d.read8(247),e=d.read8(248);b((a<<16)+(c<<8)+e>>8-d.oss)},a)};c.prototype.getTemperature=function(b){var a=this;this.readRawTemperature(function(d){d=Math.round((d-a.ac6)*a.ac5/32768);var c=Math.round(2048*a.mc/(d+a.md));b((d+c+8)/160)})};c.prototype.getPressure=function(b){var a=this;this.readRawTemperature(function(c){a.readRawPressure(function(f){var g=\nMath.round((c-a.ac6)*a.ac5/32768),g=g+Math.round(2048*a.mc/(g+a.md)),e=g-4E3;f=Math.round((f-((4*a.ac1+(a.b2*(e*e>>12)>>11)+(a.ac2*e>>11)<<a.oss)+2>>2))/(a.ac4*(((a.ac3*e>>13)+(a.b1*(e*e>>12)>>16)+2>>2)+32768)>>15)*(5E4>>a.oss))<<1;b({pressure:f+(((f>>8)*(f>>8)*3038>>16)+(-7357*f>>16)+3791>>4),temperature:(g+8)/160})})})};c.prototype.getAltitude=function(b,a){return 44330*(1-Math.pow(b/a,1/5.255))};c.prototype.getSeaLevel=function(b,a){return b/Math.pow(1-a/44330,5.255)};exports.connect=function(b,\na){return new c(b,a)}");

• #4

allObjects

I was not aware of the fact that the debug stuff is dropped automatically... so the savings are not that much as I calculated. I'm also not sure if we are talking about exactly the same module, because there is some code I cannot find in.... NEVER MIND... pulled something else to work on than BMP085... ~~~{:(

• #5

allObjects

BMP085.min.js formatted:

function c(b,a){
	this.i2c=b;
	this.oss="undefined"!==typeof a?a:3;
	if(3<this.oss||0>this.oss)this.oss=3;
	var d=this.read8(208);
	if(85!=d)return console.log("Bad ID of: "+d),null;
	this.readCoefficients()
}
c.prototype.read16=function(b){
	this.i2c.writeTo(119,b);
	b=this.i2c.readFrom(119,2);
	return b[0]<<8|b[1]
};
c.prototype.readS16=function(b){
	this.i2c.writeTo(119,b);
	b=this.i2c.readFrom(119,2);
	b=b[0]<<8|b[1];
	return 32767<=b?b-65536:b
};
c.prototype.read8=function(b){
	this.i2c.writeTo(119,b);
	return this.i2c.readFrom(119,
	1)[0]
};
c.prototype.readCoefficients=function(){
	this.ac1=this.readS16(170);
	this.ac2=this.readS16(172);
	this.ac3=this.readS16(174);
	this.ac4=this.read16(176);
	this.ac5=this.read16(178);
	this.ac6=this.read16(180);
	this.b1=this.readS16(182);
	this.b2=this.readS16(184);
	this.mb=this.readS16(186);
	this.mc=this.readS16(188);
	this.md=this.readS16(190)
};
c.prototype.readRawTemperature=function(b){
	this.i2c.writeTo(119,[244,46]);
	var a=this;
	setTimeout(function(){
	b(a.read16(246))},5)
};
c.prototype.readRawPressure=function(b){
this.i2c.writeTo(119,[244,52+(this.oss<<6)]);
	var a,d=this;
	switch(this.oss){
		case 0:a=5;
		break;
		case 1:a=8;
		break;
		case 2:a=14;
		break;
		case 3:a=26
	}
	setTimeout(function(){
			var a=d.read8(246),c=d.read8(247),e=d.read8(248);
			b((a<<16)+(c<<8)+e>>8-d.oss)
		},a)
};
c.prototype.getTemperature=function(b){
	var a=this;
	this.readRawTemperature(function(d){
		d=Math.round((d-a.ac6)*a.ac5/32768);
		var c=Math.round(2048*a.mc/(d+a.md));
		b((d+c+8)/160)})
};
c.prototype.getPressure=function(b){
	var a=this;
	this.readRawTemperature(function(c){
		a.readRawPressure(function(f){
			var g=Math.round((c-a.ac6)*a.ac5/32768),g=g+Math.round(2048*a.mc/(g+a.md)),e=g-4E3;
			f=Math.round((f-((4*a.ac1+(a.b2*(e*e>>12)>>11)+(a.ac2*e>>11)<<a.oss)+2>>2))
					/(a.ac4*(((a.ac3*e>>13)+(a.b1*(e*e>>12)>>16)+2>>2)+32768)>>15)*(5E4>>a.oss))<<1;
			b({pressure:f+(((f>>8)*(f>>8)*3038>>16)+(-7357*f>>16)+3791>>4),temperature:(g+8)/160})
		})
	})
};
c.prototype.getAltitude=function(b,a){
	return 44330*(1-Math.pow(b/a,1/5.255))
};
c.prototype.getSeaLevel=function(b,a){
	return b/Math.pow(1-a/44330,5.255)
};
exports.connect=function(b,a){return new c(b,a)}

There is not much you can do about...

I just wonder what the nested inline runtime function creation does to memory consumption...

• #6

Gordon

Hmm - interesting that the initial string itself makes it blow up.

No sure what to suggest - I imagine that the 12 byte JsVars mean it's not quite as efficient at storing data in the normal, extendable String format
• #7

tve

Do the 12-byte JSvars not support the extendable string format?
• #8

Gordon
Oh, they do - but as each var needs a pointer and flags, the efficiency goes down.
- On 16 byte vars, you've got 12 bytes of data in a StringExt
- On 12 byte vars, you've only got 8 bytes of data
Potentially the extra 2 bits for lastChild could maybe go into flags saving you 1 byte and letting you use 9/12 bytes for a StringExt, but it's not huge.

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Out of memory tricks?

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