DNZ

DNZ
Description	Denormalize (floating to integer)
Format	DNZ <scaling>
Code	152 0008
Affected	(T), (A), (D)
Type	User
Architecture	ND-100, ND-110

DNZ is an assembly instruction. It converts the number in the floating point accumulator to a single precision fixed point number in the A register, using the scaling of the DNZ instruction as a scaling factor.

The scaling is given to the conversion of -128 to 127 (approximately 10^-39 to 10³⁹). -1 When converting to integers, a scaling factor of -16₁₀ will give a fixed point number with the same value as the integer part of the floating point number. A larger scaling factor will result in a higher fixed point number on CPUs with 48-bit floating point units. On 32-bit floating point units a scaling factor of -16₁₀ should always be used. Other values will not cause a different result but will affect the overflow test.

The T and D registers (part of the 48-bit floating point accumulator) will be cleared after this instruction.

If the instruction causes underflow the A register will also be cleared.

If the resulting integer has an absolute value larger than 32767 overflow occurs and the error flag (Z) is set to one.

Internally the original floating point value will be truncated, and negative numbers will be converted to positive numbers before conversion, the result converted back to a negative number.

Example

• DNZ-20 (code 152360) Convert from floating point, scaling factor -16₁₀.

T-A-D value of 3.14 will result in A = 3

DNZ on 32-bit floating point CPUs

The ND-100/110 can have a 48-bit floating point CPU (standard configuration) or a 32-bit floting point CPU (customer option). For 32-bit floating point operations DNZ works as described above, except that the T register is not used or affected. On 32-bit floating point hardware only scaling factors of -16₁₀ should be used.

References

• Norsk Data Document ND–06.014.02 ND-100 REFERENCE MANUAL pages 120, 145, 146 and 240
• Norsk Data Document ND–06.029.01 ND-110 Instruction Set pages 71 and 72