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SDCC (Small Device C Compiler)
is free open source, retargettable, optimizing ANSI-C compiler by
Sandeep Dutta designed for 8 bit Microprocessors. The current
version targets Intel MCS51 based Microprocessors (8031, 8032, 8051,
8052, etc.), Dallas DS80C390
variants, Freescale (formerly Motorola) HC08 and Zilog Z80 based MCUs.
It can be retargeted for other microprocessors, support for Microchip
PIC, Atmel AVR is under development. The entire source code for the
compiler is distributed under GPL. SDCC uses ASXXXX
& ASLINK, an open source retargetable assembler &
linker. SDCC has extensive language extensions suitable for utilizing
various microcontrollers and underlying hardware effectively.
In addition to the MCU specific optimizations SDCC also does a host
of standard optimizations like:
- global sub expression elimination,
- loop optimizations (loop invariant, strength reduction of induction
variables and loop reversing),
- constant folding & propagation,
- copy propagation,
- dead code elimination
- jump tables for switch statements.
For the back-end SDCC uses a global register allocation scheme which
should be well suited for other 8 bit MCUs.
The peep hole optimizer uses a rule based substitution mechanism which
is MCU independent.
Supported data-types are:
type |
width |
default |
signed range |
unsigned range |
bool |
1 bit |
unsigned |
- |
0, 1 |
char |
8 bits, 1 byte |
signed |
-128, +127 |
0, +255 |
short |
16 bits, 2 bytes |
signed |
-32.768, +32.767 |
0, +65.535 |
int |
16 bits, 2 bytes |
signed |
-32.768, +32.767 |
0, +65.535 |
long |
32 bits, 4 bytes |
signed |
-2.147.483.648, +2.147.483.647 |
0, +4.294.967.295 |
float |
4 bytes IEEE 754 |
signed |
|
1.175494351E-38, 3.402823466E+38 |
pointer |
1, 2, 3 or 4 bytes |
generic |
|
|
The compiler also allows inline assembler code to be embedded
anywhere in a function. In addition, routines developed in assembly
can also be called.
SDCC also provides an option (--cyclomatic) to report the relative
complexity of a function. These functions can then be further optimized,
or hand coded in assembly if needed.
SDCC also comes with a companion source level debugger SDCDB. The
debugger currently uses ucSim, a free open source simulator for 8051
and other micro-controllers.
The latest SDCC version can be downloaded from http://sdcc.sourceforge.net/snap.php.Please note: the compiler will probably always be some
steps ahead of this documentation1.1.
Next: 1.2 Open Source
Up: 1. Introduction
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2008-12-05