Specifications

Altera Corporation 7–1
October 2007
7. Application Binary
Interface
This section describes the Application Binary Interface (ABI) for the
Nios
®
II processor. The ABI describes:
■ How data is arranged in memory
■ Behavior and structure of the stack
■ Function calling conventions
This chapter contains the following sections:
■ “Data Types” on page 7–1
■ “Memory Alignment” on page 7–2
■ “Register Usage” on page 7–2
■ “Stacks” on page 7–3
■ “Arguments and Return Values” on page 7–8
Data Types
Table 7–1 shows the size and representation of the C/C++ data types for
the Nios II processor.
Table 7–1. Representation of Data Types
Type Size (Bytes) Representation
char, signed char 1 2s complement (ASCII)
unsigned char 1 binary (ASCII)
short, signed short 2 2s complement
unsigned short 2 binary
int, signed int 4 2s complement
unsigned int 4 binary
long, signed long 4 2s complement
unsigned long 4 binary
float 4 IEEE
double 8 IEEE
pointer 4 binary
long long 8 2s complement
unsigned long long 8 binary
NII51016-7.2.0