Data Types; Memory Alignment - Altera Nios II User Manual

February 2014
NII51016-13.1.0
NII51016-13.1.0
This chapter describes the Application Binary Interface (ABI) for the Nios
processor. The ABI describes:
■ How data is arranged in memory
■ Behavior and structure of the stack
■ Function calling conventions

Data Types

Table 7–1. Representation of Data C/C++ Types
char, signed char
unsigned char
short, signed short
unsigned short
int, signed int
unsigned int
long, signed long
unsigned long
float
double
pointer
long long
unsigned long long

Memory Alignment

Contents in memory are aligned as follows:
A function must be aligned to a minimum of 32-bit boundary.
■
The minimum alignment of a data element is its natural size. A data element larger
■
than 32 bits need only be aligned to a 32-bit boundary.
Structures, unions, and strings must be aligned to a minimum of 32 bits.
■
Bit fields inside structures are always 32-bit aligned.
■
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Nios II Processor Reference Handbook
February 2014
7. Application Binary Interface
Type Size (Bytes) Representation
1 two's complement (ASCII)
1 binary (ASCII)
2 two's complement
2 binary
4 two's complement
4 binary
4 two's complement
4 binary
4 IEEE
8 IEEE
4 binary
8 two's complement
8 binary
®
II
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