ST20 STMICROELECTRONICS [STMicroelectronics], ST20 Datasheet - Page 6

• Manufacturer Part Number: ST20
• Description: ST20 software development and debugging tools
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

The optimizing compiler also implements a pragma, IMS_nosideeffects, whereby the user can
indicate that a function does not have any side-effects on external or static variables. The optimizer
can then use this information to make assumptions about what state can be changed by a function
invocation and hence about the validity of any previously computed expressions.
2.2.5
The full set of ANSI libraries is provided.
The standard library operates in double precision. Versions of the mathematical functions are
provided that operate on float arguments and return float values. These libraries provide improved
performance for applications where performance requirements override accuracy requirements.
A reduced C library is supplied to minimize code size for embedded systems applications. This library
is appropriate for code which does not need to access host facilities.
Collections of functions can be compiled separately with the ANSI C compiler and then combined into
a library. The linker is used to combine separately compiled functions into a program.
2.2.6
The ANSI C Toolset provides a very powerful assembler insert facility. The assembler insert facility
supports:
2.3
The toolset has been designed to support the development of embedded applications. The features
include the ability to place code and data at particular places in memory, being able to access the
ST20 instruction set efficiently from C, and to reduce the C run-time overhead to suit the application.
2.3.1
At configuration level, a program consists of its code, stack, static and heap segments. The configurer
allocates each of these separate segments a place in the memory of the processor.
By default, the configurer allocates all the code and data segments to a contiguous default block of
memory. The location of this default block and the order of the segments may be defined in the
configuration description. The configuration description can also specify that any one of the code or
data segments of an application are to be allocated to particular places in memory outside the default
block.
The compiler, linker and collector each will optionally produce a listing of how the various parts of an
application are mapped into the segments and memory.A tool is provided that can read all these map
files and produce a summary of the whole application, giving the locations of all the functions and
static variables. Information is collated about code and data segments including the start address and
size.
ST20–SWC
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Workspace allocation by coloring reduces the amount of workspace required by using the
same word for two variables when it can be determined that they are not both required at the
same time.
Libraries
Assembler inserts
Access to the full instruction set of the ST20;
Symbolic access to C variables (automatic and static);
Pseudo operations to load values into registers;
Loading results of C expressions;
Labels and jumps;
Directives for instruction sizing, stack access, return address access etc.
Support for embedded applications
Placing code and data