AMSTRAD cpc 6128 Manuel d'utilisateur télécharger pdf (Page 77)

The Amstrad CPC Firmware Guide

The Maths Firmware

&BDC1 MOVE REAL (&BD3D for the 464)

Action Copies the five bytes that are pointed to by DE to the location held in HL

Entry DE points to the source real value, and HL points to the destination

Exit

HL points to the real value in the destination, Carry is true if the move went properly, F is corrupt, and all

other registers are preserved

Notes For the 464 only, A holds the exponent byte of the real value when the routine is exited

&BD64 INTEGER TO REAL (&BD40 for the 464)

Action Converts an integer value into a real value

Entry

HL holds the integer value, DE points to the desti- nation for the real value, bit 7 of A holds the sign of

the integer value - it is taken to be negative if bit 7 is set

Exit HL points to the real value in the destination, AF and DE are corrupt, and all others are preserved

&BD67 BINARY TO REAL (&BD43 for the 464)

Action Converts a four byte binary value into a real value at the same location

Entry HL points to the binary value, bit 7 of A holds the sign of the binary value - negative if it is set

Exit

HL points to the real value in lieu of the four byte binary value, AF is corrupt, and all others are

preserved

Notes

A four byte binary value is an unsigned integer up to &FFFFFFFF and is stored with the least significant

byte first, and with the most significant byte last

&BD6A REAL TO INTEGER (&BD46 for the 464)

Action Converts a real value, rounding it into an unsigned integer value held in HL

Entry HL points to the real value

Exit

HL holds the integer value, Carry is true if the conversion worked successfully, the Sign flag holds the

sign of the integer (negative if it is set). A, IX and the other flags are corrupt, and all other registers are

preserved

Notes This rounds the decimal part down if it is less than 0.5, but rounds up if it is greater than, or equal to 0.5

&BD6D REAL TO BINARY (&BD49 for the 464)

Action Converts a real value, rounding it into a four byte binary value at the same location

Entry HL points to the real value

Exit

HL points to the binary value in lieu of the real value, bit 7 of B holds the sign for the binary value (it is

negative if bit 7 is set), AF, B and IX are corrupt, and all other registers are preserved

Notes See REAL TO INTEGER for details of how the values are rounded up or down

&BD70 REAL FIX (&BD4C for the 464)

Action

Performs an equivalent of BASIC's FIX function on a real value, leaving the result as a four byte binary

value at the same location

Entry HL points to the real value

Exit

HL points to the binary value in lieu of the real value, bit 7 of B has the sign of the binary value (it is

negative if bit 7 is set), AF, B and IX are corrupt, and all others are preserved

Notes

FIX removes any decimal part of the value, rounding down whether positive or negative - see the

BASIC handbook for more details on the FIX command

&BD73 REAL INT (&BD4F for the 464)

Action

Performs an equivalent of BASIC's INT function on a real value, leaving the result as a four byte binary

value at the same location

Entry HL points to the real value

Exit HL points to the binary value in lieu of the real value, bit 7 of B has the sign of the binary value (it is

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AMSTRAD cpc 6128 Manuel d'utilisateur Page 77

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