Projet_SETI_RISC-V/riscv-gnu-toolchain/binutils/cpu/iq2000m.cpu
2023-03-06 14:48:14 +01:00

631 lines
18 KiB
Scheme

; IQ2000-only CPU description. -*- Scheme -*-
;
; Copyright 2000, 2001, 2002, 2004, 2007, 2009 Free Software Foundation, Inc.
;
; Contributed by Red Hat Inc; developed under contract from Vitesse.
;
; This file is part of the GNU Binutils.
;
; This program is free software; you can redistribute it and/or modify
; it under the terms of the GNU General Public License as published by
; the Free Software Foundation; either version 3 of the License, or
; (at your option) any later version.
;
; This program is distributed in the hope that it will be useful,
; but WITHOUT ANY WARRANTY; without even the implied warranty of
; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
; GNU General Public License for more details.
;
; You should have received a copy of the GNU General Public License
; along with this program; if not, write to the Free Software
; Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
; MA 02110-1301, USA.
(dni andoui "and upper ones immediate" (MACH2000 USES-RS USES-RT)
"andoui $rt,$rs,$hi16"
(+ OP_ANDOUI rs rt hi16)
(set rt (and rs (or (sll hi16 16) #xFFFF)))
())
(dni andoui2 "and upper ones immediate" (ALIAS NO-DIS MACH2000 USES-RS USES-RT)
"andoui ${rt-rs},$hi16"
(+ OP_ANDOUI rt-rs hi16)
(set rt-rs (and rt-rs (or (sll hi16 16) #xFFFF)))
())
(dni orui2 "or upper immediate" (ALIAS NO-DIS MACH2000 USES-RS USES-RT)
"orui ${rt-rs},$hi16"
(+ OP_ORUI rt-rs hi16)
(set rt-rs (or rt-rs (sll hi16 16)))
())
(dni orui "or upper immediate" (MACH2000 USES-RS USES-RT)
"orui $rt,$rs,$hi16"
(+ OP_ORUI rs rt hi16)
(set rt (or rs (sll hi16 16)))
())
(dni bgtz "branch if greater than zero" (MACH2000 USES-RS)
"bgtz $rs,$offset"
(+ OP_BGTZ rs (f-rt 0) offset)
(if (gt rs 0)
(delay 1 (set pc offset)))
())
(dni bgtzl "branch if greater than zero likely" (MACH2000 USES-RS)
"bgtzl $rs,$offset"
(+ OP_BGTZL rs (f-rt 0) offset)
(if (gt rs 0)
(delay 1 (set pc offset))
(skip 1))
())
(dni blez "branch if less than or equal to zero" (MACH2000 USES-RS)
"blez $rs,$offset"
(+ OP_BLEZ rs (f-rt 0) offset)
(if (le rs 0)
(delay 1 (set pc offset)))
())
(dni blezl "branch if less than or equal to zero likely" (MACH2000 USES-RS)
"blezl $rs,$offset"
(+ OP_BLEZL rs (f-rt 0) offset)
(if (le rs 0)
(delay 1 (set pc offset))
(skip 1))
())
(dni mrgb "merge bytes" (MACH2000 USES-RD USES-RS USES-RT)
"mrgb $rd,$rs,$rt,$mask"
(+ OP_SPECIAL rs rt rd (f-10 0) mask FUNC_MRGB)
(sequence ((SI temp))
(if (bitclear? mask 0)
(set temp (and rs #xFF))
(set temp (and rt #xFF)))
(if (bitclear? mask 1)
(set temp (or temp (and rs #xFF00)))
(set temp (or temp (and rt #xFF00))))
(if (bitclear? mask 2)
(set temp (or temp (and rs #xFF0000)))
(set temp (or temp (and rt #xFF0000))))
(if (bitclear? mask 3)
(set temp (or temp (and rs #xFF000000)))
(set temp (or temp (and rt #xFF000000))))
(set rd temp))
())
(dni mrgb2 "merge bytes" (ALIAS NO-DIS MACH2000 USES-RD USES-RS USES-RT)
"mrgb ${rd-rs},$rt,$mask"
(+ OP_SPECIAL rt rd-rs (f-10 0) mask FUNC_MRGB)
(sequence ((SI temp))
(if (bitclear? mask 0)
(set temp (and rd-rs #xFF))
(set temp (and rt #xFF)))
(if (bitclear? mask 1)
(set temp (or temp (and rd-rs #xFF00)))
(set temp (or temp (and rt #xFF00))))
(if (bitclear? mask 2)
(set temp (or temp (and rd-rs #xFF0000)))
(set temp (or temp (and rt #xFF0000))))
(if (bitclear? mask 3)
(set temp (or temp (and rd-rs #xFF000000)))
(set temp (or temp (and rt #xFF000000))))
(set rd-rs temp))
())
; NOTE: None of these instructions' semantics are specified, so they
; will not work in a simulator.
;
; Architectural and coprocessor instructions.
; BREAK and SYSCALL are implemented with escape hatches to the C
; code. These are used by the test suite to indicate pass/failures.
(dni bctxt "branch and switch context" (MACH2000 DELAY-SLOT COND-CTI USES-RS)
"bctxt $rs,$offset"
(+ OP_REGIMM rs (f-rt 6) offset)
(unimp bctxt)
())
(dni bc0f "branch if copro 0 condition false" (MACH2000 DELAY-SLOT COND-CTI)
"bc0f $offset"
(+ OP_COP0 (f-rs 8) (f-rt 0) offset)
(unimp bc0f)
())
(dni bc0fl "branch if copro 0 condition false likely" (MACH2000 DELAY-SLOT COND-CTI SKIP-CTI)
"bc0fl $offset"
(+ OP_COP0 (f-rs 8) (f-rt 2) offset)
(unimp bc0fl)
())
(dni bc3f "branch if copro 3 condition false" (MACH2000 DELAY-SLOT COND-CTI)
"bc3f $offset"
(+ OP_COP3 (f-rs 8) (f-rt 0) offset)
(unimp bc3f)
())
(dni bc3fl "branch if copro 3 condition false likely" (MACH2000 DELAY-SLOT COND-CTI SKIP-CTI)
"bc3fl $offset"
(+ OP_COP3 (f-rs 8) (f-rt 2) offset)
(unimp bc3fl)
())
(dni bc0t "branch if copro 0 condition true" (MACH2000 DELAY-SLOT COND-CTI)
"bc0t $offset"
(+ OP_COP0 (f-rs 8) (f-rt 1) offset)
(unimp bc0t)
())
(dni bc0tl "branch if copro 0 condition true likely" (MACH2000 DELAY-SLOT COND-CTI SKIP-CTI)
"bc0tl $offset"
(+ OP_COP0 (f-rs 8) (f-rt 3) offset)
(unimp bc0tl)
())
(dni bc3t "branch if copro 3 condition true" (MACH2000 DELAY-SLOT COND-CTI)
"bc3t $offset"
(+ OP_COP3 (f-rs 8) (f-rt 1) offset)
(unimp bc3t)
())
(dni bc3tl "branch if copro 3 condition true likely" (MACH2000 DELAY-SLOT COND-CTI SKIP-CTI)
"bc3tl $offset"
(+ OP_COP3 (f-rs 8) (f-rt 3) offset)
(unimp bc3tl)
())
; Note that we don't set the USES-RD or USES-RT attributes for many of the following
; instructions, as it's the COP register that's being specified.
(dni cfc0 "control from coprocessor 0" (MACH2000 LOAD-DELAY USES-RT)
"cfc0 $rt,$rd"
(+ OP_COP0 (f-rs 2) rt rd (f-10-11 0))
(unimp cfc0)
())
(dni cfc1 "control from coprocessor 1" (MACH2000 LOAD-DELAY USES-RT)
"cfc1 $rt,$rd"
(+ OP_COP1 (f-rs 2) rt rd (f-10-11 0))
(unimp cfc1)
())
(dni cfc2 "control from coprocessor 2" (MACH2000 LOAD-DELAY USES-RT YIELD-INSN)
"cfc2 $rt,$rd"
(+ OP_COP2 (f-rs 2) rt rd (f-10-11 0))
(unimp cfc2)
())
(dni cfc3 "control from coprocessor 3" (MACH2000 LOAD-DELAY USES-RT YIELD-INSN)
"cfc3 $rt,$rd"
(+ OP_COP3 (f-rs 2) rt rd (f-10-11 0))
(unimp cfc3)
())
; COPz instructions are an instruction form, not real instructions
; with associated assembly mnemonics. Therefore, they are omitted
; from the ISA description.
(dni chkhdr "check header" (MACH2000 LOAD-DELAY USES-RD YIELD-INSN)
"chkhdr $rd,$rt"
(+ OP_COP3 (f-rs 9) rt rd (f-shamt 0) (f-func 0))
(unimp chkhdr)
())
(dni ctc0 "control to coprocessor 0" (MACH2000 USES-RT)
"ctc0 $rt,$rd"
(+ OP_COP0 (f-rs 6) rt rd (f-10-11 0))
(unimp ctc0)
())
(dni ctc1 "control to coprocessor 1" (MACH2000 USES-RT)
"ctc1 $rt,$rd"
(+ OP_COP1 (f-rs 6) rt rd (f-10-11 0))
(unimp ctc1)
())
(dni ctc2 "control to coprocessor 2" (MACH2000 USES-RT)
"ctc2 $rt,$rd"
(+ OP_COP2 (f-rs 6) rt rd (f-10-11 0))
(unimp ctc2)
())
(dni ctc3 "control to coprocessor 3" (MACH2000 USES-RT)
"ctc3 $rt,$rd"
(+ OP_COP3 (f-rs 6) rt rd (f-10-11 0))
(unimp ctc3)
())
(dni jcr "jump context register" (MACH2000 DELAY-SLOT UNCOND-CTI USES-RS)
"jcr $rs"
(+ OP_SPECIAL rs (f-rt 0) (f-rd 0) (f-shamt 0) FUNC_JCR)
(unimp jcr)
())
(dni luc32 "lookup chain 32 bits" (MACH2000 USES-RD USES-RT YIELD-INSN)
"luc32 $rt,$rd"
(+ OP_COP2 (f-rs 1) rt rd (f-shamt 0) (f-func 3))
(unimp luc32)
())
(dni luc32l "lookup chain 32 bits and lock" (MACH2000 USES-RD USES-RT YIELD-INSN)
"luc32l $rt,$rd"
(+ OP_COP2 (f-rs 1) rt rd (f-shamt 0) (f-func 7))
(unimp luc32l)
())
(dni luc64 "lookup chain 64 bits" (MACH2000 USES-RD USES-RT YIELD-INSN)
"luc64 $rt,$rd"
(+ OP_COP2 (f-rs 1) rt rd (f-shamt 0) (f-func 11))
(unimp luc64)
())
(dni luc64l "lookup chain 64 bits and lock" (MACH2000 USES-RD USES-RT YIELD-INSN)
"luc64l $rt,$rd"
(+ OP_COP2 (f-rs 1) rt rd (f-shamt 0) (f-func 15))
(unimp luc64l)
())
(dni luk "lookup key" (MACH2000 USES-RD USES-RT)
"luk $rt,$rd"
(+ OP_COP2 (f-rs 1) rt rd (f-shamt 0) (f-func 8))
(unimp luk)
())
(dni lulck "lookup lock" (MACH2000 USES-RT YIELD-INSN)
"lulck $rt"
(+ OP_COP2 (f-rs 1) rt (f-rd 0) (f-shamt 0) (f-func 4))
(unimp lulck)
())
(dni lum32 "lookup match 32 bits" (MACH2000 USES-RD USES-RT YIELD-INSN)
"lum32 $rt,$rd"
(+ OP_COP2 (f-rs 1) rt rd (f-shamt 0) (f-func 2))
(unimp lum32)
())
(dni lum32l "lookup match 32 bits and lock" (MACH2000 USES-RD USES-RT YIELD-INSN)
"lum32l $rt,$rd"
(+ OP_COP2 (f-rs 1) rt rd (f-shamt 0) (f-func 6))
(unimp lum32l)
())
(dni lum64 "lookup match 64 bits" (MACH2000 USES-RD USES-RT YIELD-INSN)
"lum64 $rt,$rd"
(+ OP_COP2 (f-rs 1) rt rd (f-shamt 0) (f-func 10))
(unimp lum64)
())
(dni lum64l "lookup match 64 bits and lock" (MACH2000 USES-RD USES-RT YIELD-INSN)
"lum64l $rt,$rd"
(+ OP_COP2 (f-rs 1) rt rd (f-shamt 0) (f-func 14))
(unimp lum64l)
())
(dni lur "lookup read" (MACH2000 USES-RD USES-RT YIELD-INSN)
"lur $rt,$rd"
(+ OP_COP2 (f-rs 1) rt rd (f-shamt 0) (f-func 1))
(unimp lur)
())
(dni lurl "lookup read and lock" (MACH2000 USES-RD USES-RT YIELD-INSN)
"lurl $rt,$rd"
(+ OP_COP2 (f-rs 1) rt rd (f-shamt 0) (f-func 5))
(unimp lurl)
())
(dni luulck "lookup unlock" (MACH2000 USES-RT YIELD-INSN)
"luulck $rt"
(+ OP_COP2 (f-rs 1) rt (f-rd 0) (f-shamt 0) (f-func 0))
(unimp luulck)
())
(dni mfc0 "move from coprocessor 0" (MACH2000 LOAD-DELAY USES-RT)
"mfc0 $rt,$rd"
(+ OP_COP0 (f-rs 0) rt rd (f-10-11 0))
(unimp mfc0)
())
(dni mfc1 "move from coprocessor 1" (MACH2000 LOAD-DELAY USES-RT)
"mfc1 $rt,$rd"
(+ OP_COP1 (f-rs 0) rt rd (f-10-11 0))
(unimp mfc1)
())
(dni mfc2 "move from coprocessor 2" (MACH2000 LOAD-DELAY USES-RT YIELD-INSN)
"mfc2 $rt,$rd"
(+ OP_COP2 (f-rs 0) rt rd (f-10-11 0))
(unimp mfc2)
())
(dni mfc3 "move from coprocessor 3" (MACH2000 LOAD-DELAY USES-RT YIELD-INSN)
"mfc3 $rt,$rd"
(+ OP_COP3 (f-rs 0) rt rd (f-10-11 0))
(unimp mfc3)
())
(dni mtc0 "move to coprocessor 0" (MACH2000 USES-RT)
"mtc0 $rt,$rd"
(+ OP_COP0 (f-rs 4) rt rd (f-10-11 0))
(unimp mtc0)
())
(dni mtc1 "move to coprocessor 1" (MACH2000 USES-RT)
"mtc1 $rt,$rd"
(+ OP_COP1 (f-rs 4) rt rd (f-10-11 0))
(unimp mtc1)
())
(dni mtc2 "move to coprocessor 2" (MACH2000 USES-RT)
"mtc2 $rt,$rd"
(+ OP_COP2 (f-rs 4) rt rd (f-10-11 0))
(unimp mtc2)
())
(dni mtc3 "move to coprocessor 3" (MACH2000 USES-RT)
"mtc3 $rt,$rd"
(+ OP_COP3 (f-rs 4) rt rd (f-10-11 0))
(unimp mtc3)
())
(dni pkrl "pkrl" (MACH2000 USES-RD USES-RT YIELD-INSN)
"pkrl $rd,$rt"
(+ OP_COP3 (f-rs 1) rt rd (f-shamt 0) (f-func 7))
(unimp pkrl)
())
(dni pkrlr1 "pkrlr1" (MACH2000 USES-RT YIELD-INSN)
"pkrlr1 $rt,$_index,$count"
(+ OP_COP3 (f-rs 29) rt count _index)
(unimp pkrlr1)
())
(dni pkrlr30 "pkrlr30" (MACH2000 USES-RT YIELD-INSN)
"pkrlr30 $rt,$_index,$count"
(+ OP_COP3 (f-rs 31) rt count _index)
(unimp pkrlr30)
())
(dni rb "dma read bytes" (MACH2000 USES-RD USES-RT YIELD-INSN)
"rb $rd,$rt"
(+ OP_COP3 (f-rs 1) rt rd (f-shamt 0) (f-func 4))
(unimp rb)
())
(dni rbr1 "dma read bytes using r1" (MACH2000 USES-RT YIELD-INSN)
"rbr1 $rt,$_index,$count"
(+ OP_COP3 (f-rs 24) rt count _index)
(unimp rbr1)
())
(dni rbr30 "dma read bytes using r30" (MACH2000 USES-RT YIELD-INSN)
"rbr30 $rt,$_index,$count"
(+ OP_COP3 (f-rs 26) rt count _index)
(unimp rbr30)
())
(dni rfe "restore from exception" (MACH2000)
"rfe"
(+ OP_COP0 (f-25 1) (f-24-19 0) (f-func 16))
(unimp rfe)
())
(dni rx "dma read word64s" (MACH2000 USES-RD USES-RT YIELD-INSN)
"rx $rd,$rt"
(+ OP_COP3 (f-rs 1) rt rd (f-shamt 0) (f-func 6))
(unimp rx)
())
(dni rxr1 "dma read word64s using r1" (MACH2000 USES-RT YIELD-INSN)
"rxr1 $rt,$_index,$count"
(+ OP_COP3 (f-rs 28) rt count _index)
(unimp rxr1)
())
(dni rxr30 "dma read word 64s using r30" (MACH2000 USES-RT YIELD-INSN)
"rxr30 $rt,$_index,$count"
(+ OP_COP3 (f-rs 30) rt count _index)
(unimp rxr30)
())
(dni sleep "sleep" (MACH2000 YIELD-INSN)
"sleep"
(+ OP_SPECIAL execode FUNC_SLEEP)
(unimp sleep)
())
(dni srrd "sram read" (MACH2000 USES-RT YIELD-INSN)
"srrd $rt"
(+ OP_COP2 (f-rs 1) rt (f-rd 0) (f-shamt 0) (f-func 16))
(unimp srrd)
())
(dni srrdl "sram read and lock" (MACH2000 USES-RT YIELD-INSN)
"srrdl $rt"
(+ OP_COP2 (f-rs 1) rt (f-rd 0) (f-shamt 0) (f-func 20))
(unimp srrdl)
())
(dni srulck "sram unlock" (MACH2000 USES-RT YIELD-INSN)
"srulck $rt"
(+ OP_COP2 (f-rs 1) rt (f-rd 0) (f-shamt 0) (f-func 22))
(unimp srulck)
())
(dni srwr "sram write" (MACH2000 USES-RD USES-RT YIELD-INSN)
"srwr $rt,$rd"
(+ OP_COP2 (f-rs 1) rt rd (f-shamt 0) (f-func 17))
(unimp srwr)
())
(dni srwru "sram write and unlock" (MACH2000 USES-RD USES-RT YIELD-INSN)
"srwru $rt,$rd"
(+ OP_COP2 (f-rs 1) rt rd (f-shamt 0) (f-func 21))
(unimp srwru)
())
(dni trapqfl "yield if dma queue full" (MACH2000 YIELD-INSN)
"trapqfl"
(+ OP_COP3 (f-rs 1) (f-rt 0) (f-rd 0) (f-shamt 0) (f-func 8))
(unimp trapqfl)
())
(dni trapqne "yield if dma queue not empty" (MACH2000 YIELD-INSN)
"trapqne"
(+ OP_COP3 (f-rs 1) (f-rt 0) (f-rd 0) (f-shamt 0) (f-func 9))
(unimp trapqne)
())
(dni traprel "traprel" (MACH2000 USES-RT YIELD-INSN)
"traprel $rt"
(+ OP_COP3 (f-rs 1) rt (f-rd 0) (f-shamt 0) (f-func 10))
(unimp traprel)
())
(dni wb "dma write bytes" (MACH2000 USES-RD USES-RT YIELD-INSN)
"wb $rd,$rt"
(+ OP_COP3 (f-rs 1) rt rd (f-shamt 0) (f-func 0))
(unimp wb)
())
(dni wbu "dma write bytes and unlock" (MACH2000 USES-RD USES-RT YIELD-INSN)
"wbu $rd,$rt"
(+ OP_COP3 (f-rs 1) rt rd (f-shamt 0) (f-func 1))
(unimp wbu)
())
(dni wbr1 "dma write bytes using r1" (MACH2000 USES-RT YIELD-INSN)
"wbr1 $rt,$_index,$count"
(+ OP_COP3 (f-rs 16) rt count _index)
(unimp wbr1)
())
(dni wbr1u "dma write bytes using r1 and unlock" (MACH2000 USES-RT YIELD-INSN)
"wbr1u $rt,$_index,$count"
(+ OP_COP3 (f-rs 17) rt count _index)
(unimp wbr1u)
())
(dni wbr30 "dma write bytes using r30" (MACH2000 USES-RT YIELD-INSN)
"wbr30 $rt,$_index,$count"
(+ OP_COP3 (f-rs 18) rt count _index)
(unimp wbr30)
())
(dni wbr30u "dma write bytes using r30 and unlock" (MACH2000 USES-RT YIELD-INSN)
"wbr30u $rt,$_index,$count"
(+ OP_COP3 (f-rs 19) rt count _index)
(unimp wbr30u)
())
(dni wx "dma write word64s" (MACH2000 USES-RD USES-RT YIELD-INSN)
"wx $rd,$rt"
(+ OP_COP3 (f-rs 1) rt rd (f-shamt 0) (f-func 2))
(unimp wx)
())
(dni wxu "dma write word64s and unlock" (MACH2000 USES-RD USES-RT YIELD-INSN)
"wxu $rd,$rt"
(+ OP_COP3 (f-rs 1) rt rd (f-shamt 0) (f-func 3))
(unimp wxu)
())
(dni wxr1 "dma write word64s using r1" (MACH2000 USES-RT YIELD-INSN)
"wxr1 $rt,$_index,$count"
(+ OP_COP3 (f-rs 20) rt count _index)
(unimp wxr1)
())
(dni wxr1u "dma write word64s using r1 and unlock" (MACH2000 USES-RT YIELD-INSN)
"wxr1u $rt,$_index,$count"
(+ OP_COP3 (f-rs 21) rt count _index)
(unimp wxr1u)
())
(dni wxr30 "dma write word64s using r30" (MACH2000 USES-RT YIELD-INSN)
"wxr30 $rt,$_index,$count"
(+ OP_COP3 (f-rs 22) rt count _index)
(unimp wxr30)
())
(dni wxr30u "dma write word64s using r30 and unlock" (MACH2000 USES-RT YIELD-INSN)
"wxr30u $rt,$_index,$count"
(+ OP_COP3 (f-rs 23) rt count _index)
(unimp wxr30u)
())
; Load/Store instructions.
(dni ldw "load double word" (MACH2000 EVEN-REG-NUM LOAD-DELAY USES-RT)
"ldw $rt,$lo16($base)"
(+ OP_LDW base rt lo16)
(sequence ((SI addr))
(set addr (and (add base lo16) (inv 3)))
(set (reg h-gr (add (ifield f-rt) 1)) (mem SI addr))
(set rt (mem SI (add addr 4))))
())
(dni sdw "store double word" (MACH2000 EVEN-REG-NUM USES-RT)
"sdw $rt,$lo16($base)"
(+ OP_SDW base rt lo16)
(sequence ((SI addr))
(set addr (and (add base lo16) (inv 3)))
(set (mem SI (add addr 4)) rt)
(set (mem SI addr) (reg h-gr (add (ifield f-rt) 1))))
())
; Jump instructions
(dni j "jump" (MACH2000)
"j $jmptarg"
(+ OP_J (f-rsrvd 0) jmptarg)
(delay 1 (set pc jmptarg))
())
(dni jal "jump and link" (MACH2000 USES-R31)
"jal $jmptarg"
(+ OP_JAL (f-rsrvd 0) jmptarg)
(delay 1
(sequence ()
(set (reg h-gr 31) (add pc 8))
(set pc jmptarg)))
())
(dni bmb "branch if matching byte-lane" (MACH2000 USES-RS USES-RT)
"bmb $rs,$rt,$offset"
(+ OP_BMB rs rt offset)
(sequence ((BI branch?))
(set branch? 0)
(if (eq (and rs #xFF) (and rt #xFF))
(set branch? 1))
(if (eq (and rs #xFF00) (and rt #xFF00))
(set branch? 1))
(if (eq (and rs #xFF0000) (and rt #xFF0000))
(set branch? 1))
(if (eq (and rs #xFF000000) (and rt #xFF000000))
(set branch? 1))
(if branch?
(delay 1 (set pc offset))))
())
; Macros
(dnmi ldw-base-0 "load double word - implied base 0" (MACH2000 EVEN-REG-NUM LOAD-DELAY USES-RT USES-RS NO-DIS)
"ldw $rt,$lo16"
(emit ldw rt lo16 (base 0))
)
(dnmi sdw-base-0 "store double word - implied base 0" (MACH2000 EVEN-REG-NUM USES-RT NO-DIS)
"sdw $rt,$lo16"
(emit sdw rt lo16 (base 0))
)