IDEC High Performance Series - Manual (Page 33)

WindO/I-NV2 User’s Manual 2-3
1 WindO/I-NV2 Specifications
2
WindO/I
-NV2 F
eatures & B
asic Oper
ations
Example: Data handling
float32
Data is handled as a 32-bit floating-point real number. The number of significant digits is 6 digits. The
floating-point type data format conforms to the IEEE (The Institute of Electrical and Electronics Engineers)
standard for the single precision storage format as explained next.
Single precision floating-point values in IEEE 754 (32 bits)
Single precision floating-point values in IEEE 754 are expressed with a total of 32 bits (2 words) using 1 bit
for the sign s, 8 bits for the exponent e, and 23 bits for the significand f. The sign bit indicates the sign of
the expressed value (positive or negative). The exponent is an 8 bit signed integer with a value from -128
to 127.
Example:
If all bits are 0, the value is “0”.
Data type Data handling
s e (exponent) [bit 30 to 23]
bit
31 bit
23
f (significand) [bit 22 to 0]
Represents after the decimal of 1.xxx +127
Sign bit (0: positive, 1: negative)
bit
22 bit
0
bit
30
s e f
0 0 1 1 1 1 1 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
1 . 1 × 2 - 2
The internal representation of float32 is described here, but the data for float32 (floating-point real
numbers) is handled with a special bit configuration, so do not directly access the bits.
Data type Storing 0FFF (hex) in LDR10 Storing FFFF (hex) in LDR10
BIN16 (+)
0FFF (hex) is handled as 4095 (dec). FFFF (hex) is handled as 65535 (dec).
BIN16 (+/-)
0FFF (hex) is handled as 4095 (dec). Sign bit is 1, so FFFF (hex) is two’s complement,
handled as -1 (dec).
Data type
Storing 0FFF (hex) in LDR10, FFFF (hex) in
LDR11
Storing FFFF (hex) in LDR10, FFFF (hex) in
LDR11
BIN32 (+)
0FFFFFFF (hex) is handled as 268435455 (dec). FFFFFFFF (hex) is handled as 4294967295 (dec).
BIN32 (+/-)
The sign bit is 0, so the positive number 0FFFFFFF
(hex) is handled as 268435455 (dec).
Sign bit is 1, so two’s complement of the negative
number FFFFFFFF (hex), handled as -1 (dec).
bit bit
15 0
0FFF (Hex)
LDR10
0000111111111111
bit bit
15 0
FFFF (Hex)
LDR10
111111111111 1111
bit bit
15 0
0FFF (Hex)
LDR10
1111 1111 1111 0000
+
bit bit
15 0
FFFF (Hex)
LDR10
1111 1111 1111 1111
−
bit
31 bit
0
LDR11 LDR10
00001111111111111111111111111111
0FFFFFFF (Hex)
bit
31 bit
0
LDR11 LDR10
1111111111111111111111111111
FFFFFFFF (Hex)
1111
bit
31 bit
0
LDR11 LDR10
00001111111111111111111111111111
0FFFFFFF (Hex) +
bit
31 bit
0
LDR11 LDR10
11111111111111111111111111111111
FFFFFFFF (Hex) −