21264/EV68A Hardware Reference Manual
Alpha Instruction Set A–11

VAX Floating-Point Instructions

Programming Note:
In orderto use CMPTxx with software completiontrap handling, it is necessary to
specifythe /SU IEEE trap mode, even though an underflow trap is not possible. In order
to use CVTQS or CVTQT with software completiontrap handling, it is necessary to
specifythe /SUI IEEE trap mode, even though an underflow trap is not possible.
A.4 VAX Floating-Point Instructions
TableA–6 lists the hexadecimal value of the 11-bit functioncode field for the VAX
floating-pointinstructions. The opcode for these instructions is 1516.
A.5 Independent Floating-Point Instructions
TableA–7 lists the hexadecimal value of the 11-bit functioncode field for the floating-
pointinstructions that are not directly tied to IEEE or VAX floating point.The opcode
for thefollowing instructions is 1716.
Table A–6 VAX Floating-Point Instructio n Function Codes
Mnemonic None /C /U /UC /S /SC /SU /SUC
ADDF 080 000 180 100 480 400 580 500
ADDG 0A0 020 1A0 120 4A0 420 5A0 520
CMPGEQ 0A5 4A5
CMPGLE 0A7 4A7
CMPGLT 0A6 4A6
CVTDG 09E 01E 19E 11E 49E 41E 59E 51E
CVTGD 0AD 02D 1AD 12D 4AD 42D 5AD 52D
CVTGF 0AC 02C 1AC 12C 4AC 42C 5AC 52C
CVTGQ Seeb elow
CVTQF 0BC 03C
CVTQG 0BE 03E
DIVF 083 003 183 103 483 403 583 503
DIVG 0A3 023 1A3 123 4A3 423 5A3 523
MULF 082 002 182 102 482 402 582 502
MULG 0A2 022 1A2 122 4A2 422 5A2 522
SQRTF 08A 00A 18A 10A 48A 40A 58A 50A
SQRTG 0AA 02A 1AA 12A 4AA 42A 5AA 52A
SUBF 081 001 181 101 481 401 581 501
SUBG 0A1 021 1A1 121 4A1 421 5A1 521
Mnemonic None /C /V /VC /S /SC /SV /SVC
CVTGQ 0AF 02F 1AF 12F 4AF 42F 5AF 52F