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NII-PRG | 2018.04.18
7. Application Binary Interface
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
7.1. Data Types
Table 82.
Representation of Data C/C++ Types
Type
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
7.2. 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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Size (Bytes)
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
Representation
ISO
9001:2008
Registered
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