Assembler Concepts Copyright 2008 by David Woolbright

Sets the condition code:

• High – result > 0 Test with BP, BNP
• Low – result < 0 Test with BM, BNM
• Equal – result = 0 Test with BZ, BNZ

Packed Arithmetic

• X DS PL8

• Y DC PL4’123’

• ZAP X,Y

• AP X,X

• SP X,=P’1’

• ZAP X,X

• BP THERE

Packed Arithmetic - MP

• SS2 – Multiply packed

• Op1 – Target Field (max 16 bytes)

• Op2 – Source Field (max 8 bytes)

• The target contains the product of multiplying Op1 by Op2

• Does not set the condition code

• Op1 contains the multiplicand (before) and then the product (after)

• Op2 contains the multiplier

• The number of leading bytes of zeros in op1 before multiplying must be >= no of bytes in op2

Packed Arithmetic

• X DS PL8

• Y DC PL4’20’

• Z DC PL4’30

• ZAP X,Y

• MP X,Z

• ZAP X,=PL5’123456789’

• MP X,Y PROBLEM

Packed Arithmetic - DP

• SS2 – Divide packed

• Op1 – Target Field (max 16 bytes) Dividend/Quotient/Remainder

• Op2 – Source Field (max 8 bytes) Divisor

• The target initially contains the dividend

• After dividing, target contains quotient and remainder

• Remainder size = divisor size

• Quotient size = Target field size – Remainder size

• Does not set the condition code

• The number of leading bytes of zeros in op1 before dividing must be >= no of bytes in op2

Packed Arithmetic

• X DS PL8 COMPUTE 125/30

• Y DC PL5’125’

• Z DC PL3’30

• ZAP X,Y

• DP X,Z

• X Before divide: 000000000000125C

• X After divide: 000000004C00005C

• Quotient Remainder

Packed Arithmetic - CP

• SS2 – Compare packed

• Op1 – Target Field (max 16 bytes)

• Op2 – Source Field (max 16 bytes)

• Sets the condition code to indicate how Op1 compares with Op2

• Numbers are compared arithmetically (not a character compare)

• Fields can be different sizes

Packed Arithmetic

• X DC PL8’-30’

• Y DC PL5’125’

• Z DC PL3’30’

• CP X,Y CC = LOW

• CP Y,X CC = HIGH

• CP Y,=P’125’ CC = EQUAL

• CP Z,=X’030F’ CC = EQUAL

Packed Arithmetic - SRP

• SS – Shift and Round Packed

• Used to shift packed fields to the left or right in order to compute decimal precision

• Op1 – Target Field (max 16 bytes)

• Op2 – A shift factor

• Positive shift factor 1-31 – left shift
• Negative shift factor in 2’s complement – right shift
• Express negative shift factor as 64 – n for n digit shift right

• Op3 – Rounding factor – (0-9)

• 0 – no rounding
• 5 – standard rounding

• Don’t shift a significant digit off the left

Packed Arithmetic

• X DC P’-98765’

• Y DC PL5’98765’

• SRP X,64-3,5 X = 00099D

• SRP Y,3,0 X = 098765000C

• SRP Y,64-1,0 X = 000009876C

• SRP X,1,0 ERROR

Shift Computations

• X DS PL4 2 DECIMALS

• Y DS PL4 3 DECIMALS

• WORK DS PL10

• Compute X + Y to 2 decimals rounded

• ZAP WORK,X

• SRP WORK,1,0

• AP WORK,Y

• SRP WORK,64-1,5

Shift Computations

• X DS PL4 2 DECIMALS

• Y DS PL4 3 DECIMALS

• WORK DS PL10

• Compute X / Y to 2 decimals rounded

• 9999v999 99999v990000

• ZAP WORK,X

• SRP WORK,4,0

• DP WORK,Y

• SRP QUOT,64-1,5

Shift Computations

• X DS PL4 4 DECIMALS

• WORK DS PL8

• COUNT DS P’9’

• Compute X10 TO 4 decimals rounded

• ZAP WORK,X

• LOOP EQU *

• MP WORK,X

• SRP WORK,64-4,5

• SP COUNT,=P’1’

• BNZ LOOP

Converting from Packed to Numeric Edited Data

• Packed instruction - ED

• SS2

• Edit Pattern describes the output

• X’40’ blank, fill pattern
• X’20’ digit selector
• X’21’ digit selector and significance starter
• X’6B’ comma
• X’4B’ decimal point

Edit Patterns

• An edit pattern is defined in hex and is called the edit “word”

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