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Joseph Poirier 2015-06-10 16:23:14 -05:00
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README.md
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# Description # Description
PicoC is a very small C interpreter for scripting. It was originally written PicoC is a very small C interpreter for scripting. It was originally written
as a script language for a UAV's on-board flight system. It's also very as a script language for a UAV on-board flight system. It's also very
suitable for other robotic, embedded and non-embedded applications. suitable for other robotic, embedded and non-embedded applications.
The core C source code is around 3500 lines of code. It's not intended to be The core C source code is around 3500 lines of code. It's not intended to be
@ -14,6 +14,7 @@ still keeping the code readable.
It's been tested on x86-32, x86-64, powerpc, arm, ultrasparc, HP-PA and blackfin It's been tested on x86-32, x86-64, powerpc, arm, ultrasparc, HP-PA and blackfin
processors and is easy to port to new targets. processors and is easy to port to new targets.
Originally forked from https://github.com/zsaleeba/picoc Originally forked from https://github.com/zsaleeba/picoc
@ -123,12 +124,14 @@ Note, you can quit picoc's interactive mode using control-D.
# Environment variables # Environment variables
In some cases you may want to change the picoc stack space. The default stack In some cases you may want to change the picoc stack space. The default stack
size is 128KB which should be large enough for most programs. size is 128KB which should be large enough for most programs.
To change the stack size you can set the STACKSIZE environment variable to a To change the stack size you can set the STACKSIZE environment variable to a
different value. The value is in bytes. different value. The value is in bytes.
# Compiling picoc # Compiling picoc
picoc can be compiled for a UNIX/Linux/POSIX host by typing "make". picoc can be compiled for a UNIX/Linux/POSIX host by typing "make".
@ -185,7 +188,7 @@ functions for your system. If your system is called "foobar" you'll be using:
We'll start by defining a simple function in library_foobar.c. We need to do two things: We'll start by defining a simple function in library_foobar.c. We need to do two things:
* add the function prototype to our list of picoc library functions * add the function prototype to our list of picoc library functions
*define the native C implementation of the function * define the native C implementation of the function
## The prototype list ## The prototype list
Each of the library_XXX.c files defines a list of picoc prototypes for each of Each of the library_XXX.c files defines a list of picoc prototypes for each of
@ -258,7 +261,6 @@ int IntValue = *(int *)Param[0]->Val->NativePointer;
``` ```
## Passing strings / char * ## Passing strings / char *
In this example I'll be reading a 'char *' parameter. It's pretty similar to In this example I'll be reading a 'char *' parameter. It's pretty similar to
the 'int *' example above: the 'int *' example above:
@ -351,7 +353,6 @@ Unions work exactly the same way as structures. Define the prototype as "union"
rather than "struct" and you're away. rather than "struct" and you're away.
## Returning values ## Returning values
Returning values from library functions is very much like accessing parameters. Returning values from library functions is very much like accessing parameters.
The type of return values is already set before your native C function is called The type of return values is already set before your native C function is called
so all you have to do is fill in the value. so all you have to do is fill in the value.
@ -384,7 +385,6 @@ Take a look at clibrary.c for the full definition of LibPrintf() if you need a
more complete example. more complete example.
## Sharing native values with picoc ## Sharing native values with picoc
Sometimes you have native variables you'd like to share with picoc. We can Sometimes you have native variables you'd like to share with picoc. We can
define a picoc value which shares memory with a native variable. Then we store define a picoc value which shares memory with a native variable. Then we store
this variable in the picoc symbol table so your programs can find it by name. this variable in the picoc symbol table so your programs can find it by name.
@ -405,7 +405,7 @@ being written by the last parameter "IsWritable" being set to FALSE. Set it to
TRUE and picoc will be able to write it too. TRUE and picoc will be able to write it too.
# How picoc differs from C90 # How PicoC differs from C90
picoc is a tiny C language, not a complete implementation of C90. It doesn't aim picoc is a tiny C language, not a complete implementation of C90. It doesn't aim
to implement every single feature of C90 but it does aim to be close enough that to implement every single feature of C90 but it does aim to be close enough that