National Instruments AutoCode NI MATRIX User Manual
Page 46
Chapter 2
C Language Reference
© National Instruments Corporation
2-29
A typical fixed-point type looks like the following:
RT_USHORT06
where USHORT stands for unsigned short, and 06 indicates the radix
position.
Fixed-point variables that are always positive in nature can be declared as
unsigned. This has the advantage of providing one more bit of accuracy
than with signed fixed-point variables, because the most significant bit is
used for storing the sign in that data type.
Example 2-2 shows some of the I/O type declarations. Only the significant
parts of the code are shown.
Example 2-2
Fixed-Point C I/O Type Declarations
struct _Subsys_1_out {
RT_SSHORT13 SS13;
RT_SSHORT15 SS15;
RT_SSHORT15 SS15_1;
RT_USHORT14 US14;
RT_USHORT10 US10;
RT_SSHORT13 SS13_1;
RT_SSHORT12 SS12;
RT_SSHORT08 SS8;
short
16
unsigned
RT_USHORT
(radix 00)
RT_USHORTxx (xx = radix 48
to –16)
signed
RT_SSHORT
(radix 00)
RT_SSHORTxx (xx = radix 48
to –16)
long
32
unsigned
RT_ULONG
(radix 00)
RT_ULONGxx (xx = radix 48 to –16)
signed
RT_SLONG
(radix 00)
RT_SLONGxx (xx = radix 48 to –16)
Table 2-6. AutoCode/C Data Types (Continued)
Data
Type
Number
of Bits
Signed or
Unsigned
Data Type Name