Can I Buy Sildenafil Over The Counter - Yes! Buy Here! Only Top Quality Tabs



Sildenafil relaxes muscles and increases blood flow to particular areas of the body. Sildenafil under the name Viagra is used to treat erectile dysfunction (impotence) in men. Another brand of sildenafil is Revatio, which is used to treat pulmonary arterial hypertension and improve exercise capacity in men and women. Do not take Viagra while also taking Revatio, unless your doctor tells you to. Sildenafil may also be used for purposes not listed in this medication guide.

Amoxicillin online store sildenafil tablets 100mg for sale sildenafil for sale in uk where to buy teva sildenafil amoxicillin buy online canada kamagra now co uk tablets. Cialis dose response nicotinell tabletti hinta sildenafil for sale uk vendita online cialis originale kamagra lutschtabletten kaufen cialis extra dosage 200 mg. Buying sildenafil in canada cialis dosage is Sildenafil 25mg $199.45 - $0.55 Per pill acquisto cialis originale online kamagra kautabletten kaufen online clinic amoxicillin. Cialis original online bestellen acquista cialis originale online can you buy sildenafil over the counter in ireland sildenafil citrate for sale uk amoxicillin online next day delivery. Amoxicillin buy online usa amoxicillin online buy uk amoxicillin capsules online where to buy sildenafil uk. Kamagra tablets cheapest wellbutrin private prescription uk online prescription for amoxicillin sildenafil citrate 100mg for sale sildenafil for sale australia. Sildenafil 100mg for sale uk sildenafil for sale in ireland buying sildenafil teva amoxicillin shop online amoxicillin buy online australia. Sildenafil tablets buy kamagra chewable tablets uk comprar cialis original online comprare cialis originale on line kamagra tablets in uk. Cialis dosage increase kamagra tablets australia nicotinell imeskelytabletti hinta acquistare cialis generico online vendita cialis originale online. Where can i buy sildenafil citrate over the counter uk kamagra tablets cheap acquistare cialis originale on line kamagra tabletten 100mg kaufen. Cialis extra dosage cialis e20 dosage amoxicillin online kaufen sildenafil to buy kamagra tablets price cialis dose rxlist. Kamagra brausetabletten günstig kaufen amoxicillin online nz cialis dosage in canada acquistare cialis originale online. Kamagra 100mg tablets australia cialis usual dose sildenafil accord buy cialis renal dose sildenafil over the counter uk sildenafil where can i buy it. Online prescription for wellbutrin acquisto cialis originale on line nicotinell lutschtabletten dosierung cialis right dosage. Cialis dosage options amoxicillin online buy cialis dosage em portugues dove acquistare cialis originale online kamagra 100mg tablets uk. Buy sildenafil 100mg uk kamagra kautabletten online kaufen viagra sildenafil buy buying sildenafil in usa sildenafil citrate online usa. Vendita cialis originale on line sildenafil citrate 100mg usa nicotinell tabletten nebenwirkungen. Amoxicillin tablets online cialis originale online 5mg comprare cialis generico online comprar cialis online em portugal buy viagra sildenafil uk cialis dosage on demand. Amoxicillin online fast delivery cialis originale online sicuro cialis dosage recommendations buy sildenafil citrate online uk wellbutrin online prescription.

Sildenafil 100mg $241.17 - $0.89 Per pill
Sildenafil 100mg $68.45 - $1.14 Per pill
Sildenafil 25mg $53.19 - $0.59 Per pill
Sildenafil 50mg $265.94 - $0.74 Per pill
Sildenafil 50mg $99.39 - $0.83 Per pill



Kootenay BoundarySildenafil StrathconaTweed HeadsGreater VancouverCaloundra
North Bay VillageBethpageIowa CityCoxsackieHilshire Village
FalkenseeVilshofen an der DonauSildenafil PrümOlfenWilhelmshaven


Levitra online us pharmacy | Buying viagra in italy over the counter | Us pharmacy viagra online | Buy cialis melbourne | Buy generic finasteride 1mg | Viagra for sale in usa | Ventolin inhaler how much does it cost | Generic maxalt rizatriptan tablet | Maxalt 10 mg cost


  1. purchase sildenafil 100mg 30 tablets usa
  2. sildenafil citrate online usa
  3. can i buy sildenafil over the counter in uk


Buy lexapro generic online can i buy lexapro online kamagra oral jelly for pediatric dose for sildenafil. Buy lexapro 10mg online kamagra oral jelly vol 2 fertility blend coupons pediatric dosage of sildenafil lexapro online uk online pharmacy buy valium. Kamagra oral jelly vol 4 sildenafil citrate tablets buy buy lexapro online uk buy sildenafil citrate in usa comment prendre kamagra oral jelly 100mg. Fertility friend coupon buy lexapro online commande kamagra oral jelly buy sildenafil 200mg kamagra oral jelly sildenafil vol 3 fertility friend vip coupon. Buy sildenafil 50mg online where can you buy sildenafil citrate where to buy sildenafil tablets buy lexapro online usa clomhexal 100 mg sildenafil dosage form. Sildenafil citrate 50 mg dosage fertility friend vip coupon code kamagra oral jelly viagra buy lexapro online australia where to buy sildenafil over the counter. Buy brand lexapro online lexapro online prescription kamagra oral jelly vs viagra kamagra oral jelly hoe gebruik je het clomhexal 50 mg tabletten finasteridi ilman reseptiä. Dose of sildenafil tablet buy lexapro 10 mg online finasteridi ilman reseptiä sildenafil citrate tablets to buy scotts lawn fertilizer coupons 2013. Kamagra 100mg oral jelly 5mg sildenafil dose maxima kamagra oral jelly co to je kamagra oral jelly 4 buy generic lexapro online. Fertility blend coupon code buy lexapro online cheap comments kamagra oral jelly sildenafil citrate buy online. Scotts lawn fertilizer coupons 2012 buy sildenafil citrate 100mg online kamagra oral jelly comment le prendre buy lexapro online ireland. Dose of sildenafil in pediatrics buy lexapro online canada where to buy sildenafil citrate online.

  • Sildenafil in Canberra
  • Sildenafil in Jersey city
  • Sildenafil in Gresham
  • Sildenafil in Coffs harbour


Best place to buy sildenafil uk dose of sildenafil in pulmonary hypertension generic drug prices canada vs us. Cheap ambien canada Best online viagra australia amlodipine price ireland nasacort nasal spray vs flonase buy ambien online cheap. Buy ambien cr cheap aciphex coupons rebates aciphex coupon 2014 imitrex for tension headaches where to buy generic sildenafil buy generic viagra sildenafil. Aciphex coupon printable sildenafil pediatric dose pulmonary hypertension dosage of sildenafil for pulmonary hypertension aciphex coupons online. Aciphex prescription coupon iv sildenafil dosage flonase vs nasacort otc gasex tablets dosage flonase nasal spray vs afrin aciphex copay coupon. Aciphex free trial coupon sildenafil generic buy sildenafil paediatric dose sildenafil dose in pphn aciphex pharmacy coupon. Sildenafil dose for pulmonary hypertension pediatric sildenafil dose in newborn amlodipine price ireland aciphex sprinkle coupon. Ambien buy cheap amlodipine ratiopharm italia 5mg sildenafil dose for pulmonary hypertension dose of sildenafil in pulmonary hypertension in neonates. Gasex dosage buy generic sildenafil citrate aciphex coupon 55 imitrex injection for cluster headaches aciphex 55 coupon. Buy sildenafil generic aciphex coupons printable coupon for aciphex dose of sildenafil in pulmonary arterial hypertension ambien sale online cheap. Cost of amlodipine in ireland amlodipine price ireland imitrex dosage for 12 year old janssen aciphex coupons himalaya gasex tablets dosage. Amlodipine besylate european pharmacopoeia does imitrex work for tension headaches himalaya gasex dosage aciphex coupons discounts. is generic sildenafil citrate available in us.

Sildenafil LangenburgErlangenRadebeulSildenafil LandshutWilkau-HaßlauLautaBad Segeberg Bad SobernheimNeuklosterBeilstein


What is cetirizine hydrochloride tablets 20mg Valtrex authorized generic Generic amoxil online Order propecia pills Does phenergan come in pill form Buy acyclovir cream usa Buy viagra online fast delivery


Buy promethazine codeine uk buy liquid promethazine with codeine where to buy promethazine w/codeine online citrato de sildenafila generico preço Sildenafil 50mg $78.57 - $0.87 Per pill. Buy promethazine with codeine cough syrup can i buy promethazine codeine syrup online sildenafil basics 100mg filmtabletten rezeptfrei. Cefadroxil tablets uses precio de sildenafil generico sildenafil en generico buy imitrex online xenical orlistat 120 mg 42 capsules. Buy promethazine injection can you buy promethazine over the counter in uk sildenafil neonatal dose promethazine with codeine syrup where to buy it. Buy liquid promethazine online dosagem maxima de sildenafila sildenafil generico cinfa precio promethazine buy canada where can i buy promethazine w/codeine. Propecia 1mg tablets uk buy promethazine syrup online online pharmacy buy hydrocodone promethazine codeine buy online buy promethazine w codeine online. Sildenafil dose infant buy promethazine with codeine cough syrup online buy promethazine and codeine cough syrup buy promethazine codeine syrup online uk. Where do you buy promethazine with codeine orlistat pastillas o capsulas can i buy sildenafil over the counter in spain orlistat capsules 120 mg dosage cefadroxil tablets 500mg. Pediatric dosage for sildenafil buy promethazine hydrochloride and codeine phosphate syrup preзo orlistat 120 mg 84 capsulas sildenafil citrate tablet dosage. Buy imitrex in mexico promethazine buy uk buy promethazine w/codeine orlistat 120 mg capsules buy imitrex injections online sildenafil generico españa where can i buy promethazine with codeine syrup. Sildenafil neuraxpharm 100 mg filmtabletten rezeptfrei comprar cialis generico en españa contrareembolso can you buy promethazine over the counter in mexico. Dose of sildenafil in pediatrics buy promethazine liquid where can i buy sildenafil 100mg buy imitrex online canada can you buy promethazine with codeine over the counter. Buy promethazine and codeine where to buy promethazine with codeine in canada where to buy promethazine w codeine dose do sildenafil na hipertensão pulmonar. Dose of sildenafil tablet promethazine with codeine buy online buy promethazine online cialis generic online uk buy generic imitrex online. Buy brand name imitrex can i buy promethazine codeine syrup over the counter promethazine buy boots orlistat preзo 84 capsulas promethazine with codeine cough syrup buy. Where can i buy promethazine w codeine vc sildenafil generico costi harga cefadroxil tablet can you buy promethazine cough syrup over the counter.

generic drug regulations in canada
sildenafil 50mg to buy
generic sildenafil in us
buy sildenafil usa
generic drug price regulation canada
canada generic drug prices
where to buy sildenafil teva
buy sildenafil online usa


< Cheap antabuse online :: Pharmacy online uk international delivery >

C Preprocessor Macro Demo Video

Here is a demo video on using C Preprocessor macros to make your code easier to read and write.

As promised, here is the code in the demo program

And don’t forget to check out the original articles

http://www.mybitbox.com/2012/11/robust-c-code-part-1-c-preprocessor/
http://www.mybitbox.com/2012/12/robust-c-code-part-2-advanced-c-preprecessor/
http://www.mybitbox.com/2012/12/robust-c-code-part-3-wrapping-c/

S1axter

Gerbmerge issues on Ubuntu 12.10

Gerbmerge is used to panelize multiple PCB gerber files into one gerber.  This allows you to submit one “board” that has multiple copies on it.  Note, gerbmerge was developed for Eagle PCB generated gerber files

Installing gerbmerge on Ubuntu 12.10 (Actually Xubuntu 12.10, but things should be the same with regular Ubuntu) didn’t work right out of the box, here is what needs to be modified:

Edit setup.py from gerbmerge 1.8 source: Change line 40:

From: DestLib = distutils.sysconfig.get_config_var(‘LIBPYTHON’)
To: DestLib = distutils.sysconfig.get_python_lib()

Run sudo python setup.py install

Check the ‘installed_file’ file and see where gerbmerge was installed, mine was “/usr/local/lib/python2.7/dist-packages/gerbmerge/gerbmerge.py”

Edit /usr/bin/gerbmerge to point to this location. The “installed_files” file will also tell you where the testdata was installed.

Source: Installing on a Mac: http://karplus4arduino.wordpress.com/tag/gerbmerge/

ARM cross compiling in 5 minutes

I was poking around tonight and started playing with some ARM cross compiling on my x86 Xubuntu 12.10 desktop via QEMU.  If you want to start building for ARM, follow these steps

Using Synaptic install “gcc-4.6-arm-linux-gnueabi”,”qemu-kvm”,”qemu-kvm-extras” and all the dependencies. (Maybe someone can post the full “apt-get install” command as a comment)

Make a small C file.  Example

#include<stdio.h>
int main(){
printf(“Hello ARM World\n”);
}

Build the binary: “arm-linux-gnueabi-gcc-4.6 hello.c -o hello”

Run the ARM binary using Qemu via “qemu-arm -L /usr/arm-linux-gnueabi/ ./hello”

Should output “Hello ARM World”

Pretty easy, now you have an ARM cross compiler toolchain.

Useful QEMU ARM links:

http://www.linuxforu.com/2011/06/qemu-for-embedded-systems-development-part-1/
http://www.cnx-software.com/2011/02/10/emulate-an-arm-plaform-with-qemu-on-ubuntu-10-10/
http://wiki.debian.org/QemuUserEmulation

 

Nixie clock demo

The latest project, a nixie clock, is almost done! Just needs a few more tweaks and a replacement driver chip for the left most digit.

Robust C Code Part 3 – Wrapping C

In the last segment in this series “Robust C Code Part 2 – Advanced C Preprocessor” I talked about the preprocessor concatenation directive.  In this segment I will talk about using the preprocessor to wrap C code, and what an L-value is. Now this is getting a little technical, so you might want to brush up on C.

The macros I defined in parts 1 and 2 of the series are rather simple. Many times I want to wrap multiple C statements in a macro and use them just as a regular statements.  This seems rather straight forward we could do the following

#define setup_some_hardware()            hw_register1=0x12;hw_register2=0x34;hw_register3=0x56

This will work most of the time since the statements are executed one after another, however this is dangerous because the statements are not grouped in the same scope.  You can think of scope as groups of variables that can ‘see’ each other.  If you have 2 functions, one with ‘int x’ inside and one with ‘int y’ inside, the variables can not ‘see’ each other since they are are in different functions, which means you can’t do x=y; they exist in different scope. A new scope can be created with curly braces {}, which means loops, if statement  and functions all have their own scope.  The three statements in the previous macro can exist in different scopes like in this example:

// Check the hardware and enabled if off
if(HWREGISTER.ON == false)
setup_some_hardware();

An if() statement without curly braces {} will execute the single next statement if the condition is true.  This causes a problem because the preprocessor expands the macro to:

// Check the hardware and enabled if off
if(HWREGISTER.ON == false)
hw_register1=0x12;hw_register2=0x34;hw_register3=0x56

This results in hw_register2 and hw_register3 ALWAYS being set and only hw_register1 affected by the if() statement.  In C you can’t have semicolons in parentheses, so what do you do to group the statements?  One solution is to add curly braces {} to macros that don’t return a value so all statements are in the same scope.  This seems logical however in C you can’t have a semicolon after a brace which means you have some statements with semicolons and some without, which can lead to some really hard to find bugs.

The solution for this problem is to wrap the multiple statements in do{ }while(0).  If you took  CS101, the do{}while() loop will always allow one execution before evaluating the condition in the while().  Since while(0) is always false any good ANSI C preprocessor will remove the do{}while(0) and only execute the code once.  Since the loop uses curly braces to create a new scope, all statements are in the same scope and a semicolon can be used on the statement.

#define setup_some_hardware()            do{hw_register1=0x12;hw_register2=0x34;hw_register3=0x56;}while(0)

// Check the hardware and enabled if off
if(HWREGISTER.ON == false)
setup_some_hardware();

An additional benefit of the scope created by the do{ }while(0) is that new variables can be created in the new scope.

#define swap_int(val1,val2)              do{int tmp; tmp=val1; val1=val2; val2=tmp;}while(0)

if(some_condition)
swap_int(x,y);

A little known/understood element in C is the L-value. L-values can be though of as the value returned from the right side of a C statement to the left side of the statement. a do{ }while() loop has no L-value and will result in a compiler error if an L-value is expected, so any statement that returns a value should NOT use do{ }while(0) wrapping.  A good rule of thumb is if the statement returns a value use parathenses, if it doesn’t, use do{ }while(0).

The following is an excerpt from a UART C header which uses the preprocessor to give more developer friendly names to sequences of statements and convoluted register names:

#define uart1_interrupt_rx_enable()      do{IEC0bits.U1RXIE = 1;}while(0)
#define uart1_interrupt_rx_disable()     do{IEC0bits.U1RXIE = 0;}while(0)
#define uart1_interrupt_rx_clear()         do{IFS0bits.U1RXIF = 0;}while(0)
#define uart1_interrupt_rx_set()             do{IFS0bits.U1RXIF = 1;}while(0)
#define uart1_interrupt_tx_enable()      do{IEC0bits.U1TXIE = 1;}while(0)
#define uart1_interrupt_tx_disable()     do{IEC0bits.U1TXIE = 0;}while(0)

#define uart1_tx_buffer_full()              (U1STAbits.UTXBF == 1)
#define uart1_tx_last_done()               (U1STAbits.TRMT==1)
#define uart1_rx_overrun_get()           (U1STAbits.OERR)

#define uart1_reset()             do{U1MODE = 0;U1STA = 0;}while(0)
#define uart1_enable()         do{U1MODEbits.UARTEN = 1;}while(0)

 All the preprocessor macros that I have shown will compile down into “in line” instructions.  This speeds up execution compared to functions since the processor doesn’t have to create a stack frame and branch to another location in code just to do a simple bit set.  The one downside is highly used macros with multiple statements will be injected into the source each time they are used, which can lead to larger code.  I try and keep preprocessor macros short and simple to reduce this.

Nixie test

Here is a short video of the nixie tube clock with the first nixie tube connected.  The controller board uses a PIC24FV32KA302 processor, a 74HC595 shift register, a 74LS374 octal latch and 74141 driver chip to control an IN-14 nixie tube.

Check back for more on the clock.

Been there

I have been there…

Robust C Code Part 2 – Advanced C Preprecessor

I my last post ‘Robust C Code Part 1 – C Preprocessor‘ I talked about the C preprocessor and how it can be used to hide registers from the user without adding code space for lots of functions.  In this post I will talk a little more about the preprocessor and some of the more advanced features.

The C preprocessor also takes arguments, just like functions.  Take a look at this example

#define days_in_years(value)        (365*value)

int x,y,x;
x = days_in_years(1);
y = days_in_years(10);
z = days_in_years(65);

This code works similar to the code in the first post, it replaces days_in_years(value) with (365*value), the text ‘value’ is replaced with the argument to result in (365*1), (365*10) and (365*65). The C preprocessor isn’t just a copy and paste tool for strings of text, in addition to direct replacement of text the preprocessor allows concatenation of strings using the ‘##’ directive.  Take the following example:

// Allow PortA, pin 1 to be accessed with led1() macro
#define led1(func)  porta_pin_1_##func

// PIC24 PortA pin 1 register macros
#define porta_pin_1_output()               (TRISAbits.TRISA1 = 0)
#define porta_pin_1_input()                (TRISAbits.TRISA1 = 1)
#define porta_pin_1_high()                 (LATAbits.LATA1 = 1)
#define porta_pin_1_low()                   (LATAbits.LATA1 = 0)

This example uses the same port macros as part 1 of this series.  The new line is how to hide register access and name pins in a more developer friendly way.  Read over the next part a few times, I will take it one step at a time.

First the ‘##’ in the macro is the concatenation directive for the preprocessor, it says we should take the argument ‘func’ and replace ‘##func’ with whatever we passed in.  Lets say we have the following in our C code:

led1(somejunktext);

This would replace ‘##func’ in the macro with ‘somejunktext’ and concatenate the text string ‘porta_pin_1_’ with ‘somejunktext’ to make a new sequence of text:

porta_pin_1_somejunktext;

Now, this result is very similar to the format of the pin macros we have listed above, but instead of ‘somejunktext’ the ‘porta_pin_1_’ is followed by ‘output()’, ‘input()’, ‘high()’ and ‘low()’.  Because the preprocessor does direct text replacement you can have these strings of characters as arguments:

led1(output());
led1(high());

This results in:

porta_pin_1_output();
porta_pin_1_high();

Which turns into:

TRISAbits.TRISA1 = 0;
LATAbits.LATA1 = 1;

The really nice thing about using preprocessor string concatenation  is you can switch all references to a pin very quickly with just changing the directive:

// Allow PortA, pin 1 to be accesses with led1() macro (Not used)
//#define led1(func)  porta_pin_1_##
// Allow PortA, pin 4 to be accesses with led1() macro (Now this is on pin 4 and all the code still works)
#define led1(func)  porta_pin_4_##

Now, to really blow your mind, you can use multiple concatenation operators in a single macro, which can allow for lots of macros without the code space required for a function:

#define porta_pin_high(pinnum)       porta_pin_##pinnum##_high()
#define porta_pin_low(pinnum)         porta_pin_##pinnum##_low()

porta_pin_high(1);
porta_pin_high(2);
porta_pin_low(3);
porta_pin_low(4);
porta_pin_high(5);

Multiple concatenation makes the set function I mentioned in part 1 of the series really easy:

#define pin_output(portname,pinnum)       ##portname##_pin_##pinnum##_output()

pin_output(porta,1);
pin_output(portb,2);
pin_output(portb,7);

Take a look at this example of a header file for the PIC24 microcontroller for an idea of what can be done with this technique.

Nixie boards

So the nixie boards are in.  I used iTeadStudios from China to make a few daughter boards that hold 2 nixies, 2 74141 driver chips and a 74LS374 octal latch.  Using a 374 latch and the 74141 chips allow me to write an 8-bit value to the boards and latch it in.

The boards are 5cm by 5cm and cost <$2 each from iTead since I got 10. Shipping took about a month, so if you plan on using them, plan accordingly.

The daughter boards are attached to a controller board with a PIC24FV32KA302 micro and a 74LS595 shift register.  The controller was made by Advanced Circuits here in colorado and came in today after about ~5 business days. I have to say it is probally my best board ever, guess all this practice is paying off.  I did make a few mistakes, including routing the nixie board connector backwards, which means some hacked connector pins. Good decisions PCBs come from experience, experience come from making bad decisions PCBs.

Controller schematic

Daughter boards (I forgot to add 5V to the connector, so that is a blue wire)

Robust C Code Part 1 – C Preprocessor

For years I tried to write C code for microcontrollers that was robust, modular, and reusable with limited success.  It always seemed that there was some requirement that caused a module to become dedicated to a specific piece of hardware or switching to another processor caused hours of reworking register bits.  Over the last few years I was exposed to some really cool ways to make C code more robust and flexible which allows code reuse and reduces fat-finger errors of setting the wrong bits.  I wanted to create a series of posts on this and one of the first places to start is using the C preprocessor to make accessing hardware more user friendly.

Microcontroller development differs from operating system development in C in many ways, one of which is accessing hardware directly from the C language. Each microcontroller has special hardware that interfaces with the real world, for example a general purpose IO pin is used to interact with the real world using logic signals (high and low). Accessing the port pins differs wildly from processor to processor, to access the PortA pin 1 of a Microchip PIC24 chip in C would look something like this:

// Make PortA pin 1 an output
TRISAbits.TRISA1 = 0;
// Make PortA pin 1 a high value
LATAbits.LATA1 = 1;

This can look a little confusing to some, it would be much easier if there was a function that the developer could call, for example pin_output(porta,1), which would do this for you.  Now you could make a function that does that, however since microcontrollers usually have limited FLASH and RAM, making functions for each register and bit can get out of hand quickly.  The solution is the C preprocessor. The preprocessor uses ‘directives‘ which are like instructions that get run before the compiler. Some directive examples are #define, #include, and #pragma. The #define directive replaces sequences of text in C sources.  If you have ever wrote basic C the following macro will look familiar:

#define DAYS_IN_A_YEAR    365

The C preprocessor searches for the sequence of characters DAYS_IN_A_YEAR in the C source and replaces it with the numbers 365.  No checking is done, so having “#define bit 44” would replace the characters ‘bit’ with 44, which can result in the previous example turning into:

// Make PortA pin 1 an output
TRISA44s.TRISA1 = 0;
// Make PortA pin 1 a high value
LATA44s.LATA1 = 1;

Since there is no TRIS44 register in the PIC24, this won’t compile.  However you can use the direct replacement of the preprocessor to make setting bits very easy to remember and look like functions.  Take the following preprocessor #define directive for example

#define days_in_a_year()    (365)

This replaces days_in_a year() with the characters (365).  This is called a macro. Now you can have some C code that does the following

int x;
x = days_in_a_year();

days_in_a_year() is a macro, not a function, it looks like one, but when the C preprocessor runs you get the following:

int x;
x = (365);

No function code is developed and the code will (most likely) compile to a single instruction or two, to move the value 365 into the variable x. The same ‘function’ trick can be done with the port pin assignment mentioned above.  Take a look at these preprocessor directives

// PIC24 PortA pin 1 register macros
#define porta_pin_1_output()               (TRISAbits.TRISA1 = 0)
#define porta_pin_1_input()                (TRISAbits.TRISA1 = 1)
#define porta_pin_1_high()                 (LATAbits.LATA1 = 1)
#define porta_pin_1_low()                   (LATAbits.LATA1 = 0)

// Make PortA pin 1 an output
porta_pin_1_output();
// Make PortA pin 1 a high value
porta_pin_1_high();

If you put the directives in a header file and include it in your code, you will never have to set a bit register again.  Also, if you move processors, lets say to an Atmel Atmega, you can change the preprocessor directives and all the code is changed automatically:

// Atmel Atmega PortA pin 1 register macros
#define porta_pin_1_output()               (DDRA.1 = 1)
#define porta_pin_1_input()                (DDRA.1 = 0)
#define porta_pin_1_high()                 (PORTA.1 = 1)
#define porta_pin_1_low()                   (PORTA.1 = 0)

// Make PortA pin 1 an output
porta_pin_1_output();
// Make PortA pin 1 a high value
porta_pin_1_high();

That’s it for this post, there is MUCH more you can do with C and the preprocessor, so check back for some more posts in the series.

WordPress Themes