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transfer functions

summary

    A transfer function is used to transfer information between variables of different types.

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transfer functions

    This subchapter looks at transfer functions.

    A transfer function is used to transfer information between variables of different types.

integer and real transfers

ALGOL    entier(E) — ALGOL-60 library function that returns the largest integer not greater than the expression.
BASIC    INT(x) — BASIC library function that returns the integer portion of an expression. The result is the largest whole number (integer) that is not greater than the expression.

integer and character/string transfers

BASIC    VAL(x) — BASIC library function that returns the integer value of a character string or expression. Note that some versions of VAL will strip out leading blanks..

BASIC    CHR$(x) — BASIC library function that returns the single element character string containing the ASCII character equivalent of an integer expression in the range of 0 to 255.
Pascal    char(x) — Pascal standard function that returns the CHAR character that matches the position in the collating sequence of an argument x.

BASIC    ASC(x) — BASIC library function that returns the decimal ASCII value of a string variable..

assembly language instructions

    Data conversion instructions change data from one format to another.

    A sign extension operation takes a small value and sign extends it to a larger storage format (such as byte to word).

    A type conversion operation changes data from one format to another (such as signed two’s complement integer into binary coded decimal).

• EXT Sign Extend; Motorola 680x0, Motorola 68300; sign extends a byte (8 bits) in a data register to a word (16 bits) or sign extends a word (16 bits) in a data register to a longword (32 bits); sets or clears flags
• CVT Convert; DEC VAX; converts a signed quantity to a different signed data type, source and destination in register or memory, special rounded versions for certain floating conversions; sets or clears flags
• CVTBW Convert Byte to Word; sign extend
• CVTBL Convert Byte to Long; sign extend
• CVTWB Convert Word to Byte; truncated
• CVTWL Convert Word to Long; sign extend
• CVTLB Convert Long to Byte; truncated
• CVTLW Convert Long to Word; truncated
• CVTBF Convert Byte to Floating; exact
• CVTBD Convert Byte to Double float; exact
• CVTWF Convert Word to Floating; exact
• CVTWD Convert Word to Double float; exact
• CVTLF Convert Long to Floating; rounded
• CVTLD Convert Long to Double float; exact
• CVTFB Convert Floating to Byte; truncated
• CVTDB Convert Double float to Byte; truncated
• CVTFW Convert Floating to Word; truncated
• CVTDW Convert Double float to Word; truncated
• CVTFL Convert Floating to Long; truncated
• CVTRFL Convert Rounded Floating to Long; rounded
• CVTDL Convert Double float to Long; truncated
• CVTRDL Convert Rounded Double float to Long; rounded
• CVTFD Convert Floating to Double float; exact
• CVTDF Convert Double float to Floating; rounded
• CBW Convert Byte to Word; Intel 80x86; sign extends a byte (8 bits) in register AL to create a word (16 bits) in the AX register; does not affect flags
• CWD Convert Word to Doubleword; Intel 80x86; sign extends a word (16 bits) in register AX throughout the DX register to create a doubleword (32 bits); does not affect flags
• CWDE Convert Word to Doubleword Extended; Intel 80386; sign extends a word (16 bits) in register AX to create a doubleword (32 bits) in the EAX register; does not affect flags
• CDQ Convert Doubleword to Quadword; Intel 80386; sign extends a doubleword (32 bits) in register EAX to create a quadword (64 bits) in the EDX register; does not affect flags
• EXTB Sign Extend Byte; Motorola 680x0, Motorola 68300; sign extends a byte (8 bits) in a data register to a longword (32 bits); sets or clears flags
• MOVSX Move with Sign Extension; Intel 80x86; moves data from a register or memory to a register, with a sign extension (conversion to larger binary integer: byte to word, byte to doubleword, or word to doubleword); does not affect flags
• MOVZX Move with Zero Extension; Intel 80x86; moves data from a register or memory to a register, with a zero extension (conversion to larger binary integer: byte to word, byte to doubleword, or word to doubleword); does not affect flags
• MOVZ Move Zero Extended; DEC VAX; converts an unsigned integer to a larger unsigned integer, source and destination in register or memory (MOVZBW Byte to Word, MOVZBL Byte to Long, MOVZWL Word to Long); sets or clears flags
• NUM Convert to Numeric; MIX; converts byte encoded character code (MIX character code) in A-register/X-register pair to numeric data in the A-register (accumulator), does not change sign, overflow possible
• CHAR Convert to Characters; MIX; converts numeric data in the A-register (accumulator) into byte encoded character code (MIX character code) in A-register/X-register pair, does not change signs
• PACK Pack; Motorola 680x0; converts byte encoded numeric data (such as ASCII or EBCDIC characters) into binary coded decimals using an adjustment field ($3030 for ASCII, $F0F0 for EBCDIC), either from data register to data register or memory location to memory location with predecrement of address pointers; does not modify flags
• UNPK Unpack; Motorola 680x0; converts binary coded decimals into byte encoded numeric data (such as ASCII or EBCDIC characters) using an adjustment field ($3030 for ASCII, $F0F0 for EBCDIC), either from data register to data register or memory location to memory location with predecrement of address pointers; does not modify flags

See also Data Conversion Instructions in Assembly Language