1. xerox 560 computer system - The UK Mirror Service

MIMULTIPLY IMMEDIATE(Immediate operand)Example 2, odd R field value:Before executionAfter execution(I) 12-31X'01234 1 X'01234 1The value field (bit positions 12-31 of the instruction word)is treated as a 20-bit, twols complement integer. MULTIPLYIMMEDIATE extends the sign of the value field (bit position12) of the instruction word 12 bit positions to the leftand multiplies the resulting 32-bit value by the contentsof register Ru1, then loads the 32 high-order bits of theproduct into register R, and then loads the 32 low-orderbits of the product into regi ster Ru 1.If R is an odd value, the result in register R is the 32 loworderbits of the product. Thus, in order to generate a64-bit product, the R field of the instruction must be evenand the multiplicand must be in register R+1. The conditioncode settings are based on the 64-bit product formedduring instruction execution, rather than on the final contentsof register R. Overflow cannot occur.Affected: (R), (Rul), CC2,CC3,CC4(Rul) x (I)12-31SE -R,Ru1Condition code settings:2 3 4 64-bi t product- - 0 0 Zero." ~ 1 _ ___ .L-. __- V I"'C~UIIVC.oo PositiveTrap: Nonexistent instructionif bit 0 is a 1.Result is correct, as represented in registerRu1.Result is not correctly representable in registerRu1 alone.(R) X'00030002 1 XI 369C2468 ICC xxxx xOlOMHMULTIPLY HALFWORD(Halfword index alignment)H 57 I R I X I: Reference: address Io 1 2 3 1 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19120 21 22 23 24 25 26 27128 29 30 31MULTIPLY HALFWORD multiplies the contents of bit positions16-31 of register R by the effective halfword (withboth halfwords treated as signed, twols complement integers)and stores the product in register Ru 1 (overflow cannotoccur). If R is an even value, the original multiplierin register R is preserved, allowing repetitive halfwordmultiplication with a constant multiplier; however, if R isan odd value, the product is loaded into the same register.Overflow cannot occur.Affected: (Rul), CC3, CC4(R)16-31 x EH -Ru1Condition code settings:2 3 4 Result in Ru 1- 0 0 Zero- 0 Negative0 PositiveExample 1, even R field value:If MI is indirectly addressed, it is treated as a nonexistentinstruction, in which case the BP unconditionally abortsexecution of the instruction (at the time of operation codedecoding) and traps to location X'40' with the contentsof register R, register Ru1, and the condition code unchanged;otherwise, the BP executes the next instructionin sequence.EH(R)(Rul)Before executionX'FFFF'XI xxxxOOOA IxxxxxxxxAfter executionX'FFFF'XI xxxxOOOA IX' FFFFFFF6 1Example 1, even R field value:CCxxxxxx01Before executionAfter executionExample 2, odd R field value:(1)12-31X '70000 I XI 70000 1Before executionAfter execution(R) xxxxxxxx X I 00007000 IEHX'FFFF 'X'FFFF'(Ru1 ) XI 10001000 1 X 170000000 I(R)XI xxxxOOOA IX' FFFFFFF6 1CC xxxx x110CCxxxxxx01Fixed-Point Arithmetic Instructions 63