Nios® II Software Developer Handbook

ID 683525
Date 8/28/2023
Public
Document Table of Contents

7.4. Data Widths and the HAL Type Definitions

For embedded processors such as the Nios® II processor, it is often important to know the exact width and precision of data. Because the ANSI C data types do not explicitly define data width, the HAL uses a set of standard type definitions instead. The ANSI C types are supported, but their data widths are dependent on the compiler’s convention.

The header file alt_types.h defines the HAL type definitions.

Table 28.  The HAL Type Definitions
Type Meaning
alt_8 Signed 8-bit integer.
alt_u8 Unsigned 8-bit integer.
alt_16 Signed 16-bit integer.
alt_u16 Unsigned 16-bit integer.
alt_32 Signed 32-bit integer.
alt_u32 Unsigned 32-bit integer.
alt_64 Signed 64-bit integer.
alt_u64 Unsigned 64-bit integer.
Table 29.  GNU Toolchain Data Widths
Type Meaning
char 8 bits.
short 16 bits.
long 32 bits.
int 32 bits.