~~~
c uxn on ilo

c This is console-only, assembled with pali. The RAM packs four
c bytes per 32-bit cell, with the lowest address in bits 0-7;
c shorts are big-endian. Guest addresses use memory helpers. The
c guest stacks and devices use one byte per cell, with circular
c stacks and 8-bit pointers, separate from ilo's stacks. Helpers
c preserve deeper operands and balance temporary entries. Jumps
c to helpers act as tail calls; related routines sometimes fall
c through to avoid call/return overhead. Stack effects describe
c ilo operands unless marked guest; a is below b, and value is
c a byte or short for the current mode. Guest stack effects
c assume keep mode is off; keep mode retains the input operands.

: uxn:start
i lica....
r uxn:load-rom
i lica....
r uxn:eval
i lica....
r uxn:console-loop

: uxn:halt
c Keep re in a separate bundle: halt I/O sets IP past memory,
c but re in the same bundle would restore the caller's IP and
c undo the halt.
i lica....
r uxn:stderr-flush
i liio....
d 6
i re......

: uxn:load-rom
c The ROM is loaded from the ilo block storage because ilo does
c not have host file system access.
i lilist..
d 0
r uxn:block

: uxn:load-next
i lifeduli
r uxn:block
d 1024
i muliad..
r uxn:ram
i liadliio
d 64
d 2
i lifeliad
r uxn:block
d 1
i dulist..
r uxn:block
i liltlicj
d 16
r uxn:load-next
i re......

: uxn:eval
i lilist..
d 1
r uxn:running

: uxn:eval-next
i lica....
r uxn:fetch
i listlica
r uxn:opcode
r uxn:decode
i lica....
r uxn:dispatch
i lifelicj
r uxn:running
r uxn:eval-next
i re......

: uxn:fetch
c (-- byte)
i lifedu..
r uxn:pc
i liadlian
d 1
d 65535
i listliju
r uxn:pc
r uxn:read-byte

: uxn:decode
i lifelian
r uxn:opcode
d 32
i listlife
r uxn:short
r uxn:opcode
i lianlist
d 128
r uxn:keep

: uxn:decode-stack
i lililife
r uxn:wsp
r uxn:working-stack
r uxn:opcode
i lianlicj
d 64
r uxn:decode-return
i liju....
r uxn:decode-selected

: uxn:decode-return
i drdrlili
r uxn:rsp
r uxn:return-stack

: uxn:decode-selected
c read-ptr is a separate pop cursor. Keep-mode pops decrement
c only this cursor; pushes start at the retained real pointer
c and increment it normally.
i listduli
r uxn:stack-base
r uxn:ptr-address
i stfelist
r uxn:read-ptr
i re......

: uxn:dispatch
i lifelian
r uxn:opcode
d 31
i liadfeju
r uxn:op-table

: uxn:read-byte
c (address -- byte)
i lianduli
d 65535
d 3
i anlimupu
d 8
i lisrliad
d 2
r uxn:ram
i feposrli
d 255
i anre....

: uxn:write-byte
c (byte address --)

i lianduli
d 65535
d 2
i srliadpu
r uxn:ram
i lianlimu
d 3
d 8
i dupuswli
d 255
i answslli
d 255
i posllixo
d -1
i podufesw
i puanorpo
i stre....

: uxn:read-short
c (address -- short)
i dulica..
r uxn:read-byte
i lislswli
d 8
d 1
i adlica..
r uxn:read-byte
i orre....

: uxn:write-short
c (short address --)

i lianpudu
d 65535
i lisrpodu
d 8
i pulica..
r uxn:write-byte
i poliad..
d 1
i liju....
r uxn:write-byte

: uxn:pop-byte
c (-- byte)
i lifelisu
r uxn:read-ptr
d 1
i lianduli
d 255
r uxn:read-ptr
i stlife..
r uxn:keep
i licj....
r uxn:pop-kept
i dulifest
r uxn:ptr-address

: uxn:pop-kept
i lifeadfe
r uxn:stack-base
i re......

: uxn:push-byte
c (byte --)
i lianlife
d 255
r uxn:ptr-address
i felifead
r uxn:stack-base
i stlifefe
r uxn:ptr-address
i liadlian
d 1
d 255
i lifestre
r uxn:ptr-address

: uxn:pop-value
c (-- value)
i lica....
r uxn:pop-byte
i lifelicj
r uxn:short
r uxn:pop-short
i re......

: uxn:pop-short
c (low-byte -- short)
i lica....
r uxn:pop-byte
i lislorre
d 8

: uxn:push-value
c (value --)
i lifelicj
r uxn:short
r uxn:push-short
i liju....
r uxn:push-byte

: uxn:push-short
c (short --)
i dulisr..
d 8
i lica....
r uxn:push-byte
i liju....
r uxn:push-byte

: uxn:other-stack
i lifelieq
r uxn:ptr-address
r uxn:wsp
i licj....
r uxn:select-return
i lilist..
r uxn:wsp
r uxn:ptr-address
i lilistre
r uxn:working-stack
r uxn:stack-base

: uxn:select-return
i lilist..
r uxn:rsp
r uxn:ptr-address
i lilistre
r uxn:return-stack
r uxn:stack-base

: uxn:device-read
c (port -- byte)
i lianliad
d 255
r uxn:devices
i fere....

: uxn:device-store
c (byte port --)
i lianliad
d 255
r uxn:devices
i pulianpo
d 255
i stre....

: uxn:device-write
c DEO2 invokes only the low-byte port callback, matching
c the sibling uxn-min.c.
c (byte port --)
i listlist
r uxn:address
r uxn:value
i lifelife
r uxn:value
r uxn:address
i lica....
r uxn:device-store
i lifelian
r uxn:address
d 255
i lieqlicj
d 17
r uxn:device-vector
i lifelian
r uxn:address
d 255
i lieqlicj
d 24
r uxn:device-output
i lifelian
r uxn:address
d 255
i lieqlicj
d 25
r uxn:device-error
i re......

: uxn:device-vector
i lilica..
d 16
r uxn:device-read
i lislli..
d 8
d 17
i lica....
r uxn:device-read
i orlistre
r uxn:console-vector

: uxn:device-output
i lifelian
r uxn:value
d 255
i liiore..
d 0

: uxn:device-error
c Build-time stderr toggle: reference stderr-empty to drop
c characters (the default), or stderr-write to
c buffer them in the block store.

c Buffered stderr stores 1024 byte values per block, one per
c 32-bit cell, starting at block 64. Each fresh image that writes
c stderr overwrites from there; older trailing blocks remain.
c uxn:halt flushes a partial block with zero padding for unused
c cells.

c Standard ilo character output has no stdout/stderr selector.

i liju....
r uxn:stderr-empty

: uxn:stderr-write
i lifelian
r uxn:value
d 255
i lifeliad
r uxn:stderr-count
r uxn:block-buffer
i st......
i lifeliad
r uxn:stderr-count
d 1
i dulistli
r uxn:stderr-count
d 1024
i eqlicj..
r uxn:stderr-flush
i re......

: uxn:stderr-flush
i lifelieq
r uxn:stderr-count
d 0
i licj....
r uxn:stderr-empty
i lifelili
r uxn:stderr-block
r uxn:block-buffer
d 3
i iolife..
r uxn:stderr-block
i liadlist
d 1
r uxn:stderr-block
i lilistli
d 0
r uxn:stderr-count
r uxn:block-buffer

: uxn:stderr-clear
c Clear the buffer so a later partial block has zero padding.
i dulisw..
d 0
i stliaddu
d 1
i liliadlt
r uxn:block-buffer
d 1024
i licj....
r uxn:stderr-clear
i dr......

: uxn:stderr-empty
i re......

: uxn:console-loop
i lilica..
d 15
r uxn:device-read
i licj....
r uxn:console-exit
i lifelieq
r uxn:console-vector
d 0
i licj....
r uxn:console-exit
i liiodu..
d 1
i lieqlicj
d -1
r uxn:console-eof
i lilica..
d 18
r uxn:device-store
i lililica
d 1
d 23
r uxn:device-store
i lica....
r uxn:console-event
i liju....
r uxn:console-loop

: uxn:console-eof
i drlili..
d 10
d 18
i lica....
r uxn:device-store
i lililica
d 4
d 23
r uxn:device-store
i lica....
r uxn:console-event

: uxn:console-exit
c Save guest exit status; ilo has no standard way to return it
c to the host.
i lilica..
d 15
r uxn:device-read
i lianlist
d 127
r uxn:exit-status
i re......

: uxn:console-event
i lifelist
r uxn:console-vector
r uxn:pc
i liju....
r uxn:eval

: uxn:op-table
r uxn:op-special
r uxn:op-inc
r uxn:op-pop
r uxn:op-nip
r uxn:op-swp
r uxn:op-rot
r uxn:op-dup
r uxn:op-ovr
r uxn:op-equ
r uxn:op-neq
r uxn:op-gth
r uxn:op-lth
r uxn:op-jmp
r uxn:op-jcn
r uxn:op-jsr
r uxn:op-sth
r uxn:op-ldz
r uxn:op-stz
r uxn:op-ldr
r uxn:op-str
r uxn:op-lda
r uxn:op-sta
r uxn:op-dei
r uxn:op-deo
r uxn:op-add
r uxn:op-sub
r uxn:op-mul
r uxn:op-div
r uxn:op-and
r uxn:op-ora
r uxn:op-eor
r uxn:op-sft

: uxn:op-special
i lilist..
d 0
r uxn:keep
i lifelisr
r uxn:opcode
d 5
i liadfeju
r uxn:imm-table

: uxn:op-inc
i lica....
r uxn:pop-value
i liadliju
d 1
r uxn:push-value

: uxn:op-pop
i lica....
r uxn:pop-value
i drre....

: uxn:op-nip
c guest (a b -- b)
i lica....
r uxn:pop-value
i lica....
r uxn:pop-value
i drliju..
r uxn:push-value

: uxn:op-swp
c guest (a b -- b a)
i lica....
r uxn:pop-value
i lica....
r uxn:pop-value
i swlica..
r uxn:push-value
i liju....
r uxn:push-value

: uxn:op-rot
c guest (a b c -- b c a)
i lica....
r uxn:pop-value
i lica....
r uxn:pop-value
i lica....
r uxn:pop-value
i pulica..
r uxn:push-value
i lica....
r uxn:push-value
i poliju..
r uxn:push-value

: uxn:op-dup
c guest (a -- a a)
i lica....
r uxn:pop-value
i dulica..
r uxn:push-value
i liju....
r uxn:push-value

: uxn:op-ovr
c guest (a b -- a b a)
i lica....
r uxn:pop-value
i lica....
r uxn:pop-value
i dupulica
r uxn:push-value
i lica....
r uxn:push-value
i poliju..
r uxn:push-value

: uxn:op-equ
c guest (a b -- boolean-byte)
i lica....
r uxn:pop-value
i lica....
r uxn:pop-value
i eqlian..
d 1
i liju....
r uxn:push-byte

: uxn:op-neq
c guest (a b -- boolean-byte)
i lica....
r uxn:pop-value
i lica....
r uxn:pop-value
i nelian..
d 1
i liju....
r uxn:push-byte

: uxn:op-gth
i lica....
r uxn:pop-value
i lica....
r uxn:pop-value
i swgtlian
d 1
i liju....
r uxn:push-byte

: uxn:op-lth
i lica....
r uxn:pop-value
i lica....
r uxn:pop-value
i swltlian
d 1
i liju....
r uxn:push-byte

: uxn:op-jmp
i lica....
r uxn:pop-value
i liju....
r uxn:move

: uxn:op-jcn
i lica....
r uxn:pop-value
i lica....
r uxn:pop-byte
i licj....
r uxn:move
i drre....

: uxn:op-jsr
i lica....
r uxn:pop-value
i lica....
r uxn:other-stack
i lifelica
r uxn:pc
r uxn:push-short
i liju....
r uxn:move

: uxn:move
c (target --)
i lifelicj
r uxn:short
r uxn:move-absolute
i lica....
r uxn:signed-byte
i lifead..
r uxn:pc

: uxn:move-absolute
c (target --)
i lianlist
d 65535
r uxn:pc
i re......

: uxn:signed-byte
c (byte -- signed-offset)
i dulilt..
d 128
i licj....
r uxn:signed-positive
i lisure..
d 256

: uxn:signed-positive
i re......

: uxn:op-sth
i lica....
r uxn:pop-value
i lica....
r uxn:other-stack
i liju....
r uxn:push-value

: uxn:op-ldz
c LDZ/STZ use address-mask so short accesses wrap within the
c zero page.
i lilist..
d 255
r uxn:address-mask
i lica....
r uxn:pop-byte
i lifean..
r uxn:address-mask
i listliju
r uxn:address
r uxn:memory-load

: uxn:op-stz
i lilist..
d 255
r uxn:address-mask
i lica....
r uxn:pop-byte
i lifean..
r uxn:address-mask
i listliju
r uxn:address
r uxn:memory-store

: uxn:op-ldr
i lilist..
d 65535
r uxn:address-mask
i lica....
r uxn:pop-byte
i lica....
r uxn:signed-byte
i lifead..
r uxn:pc
i lifean..
r uxn:address-mask
i listliju
r uxn:address
r uxn:memory-load

: uxn:op-str
i lilist..
d 65535
r uxn:address-mask
i lica....
r uxn:pop-byte
i lica....
r uxn:signed-byte
i lifead..
r uxn:pc
i lifean..
r uxn:address-mask
i listliju
r uxn:address
r uxn:memory-store

: uxn:op-lda
i lilist..
d 65535
r uxn:address-mask
i lica....
r uxn:pop-byte
i lica....
r uxn:pop-byte
i lislor..
d 8
i lifean..
r uxn:address-mask
i listliju
r uxn:address
r uxn:memory-load

: uxn:op-sta
i lilist..
d 65535
r uxn:address-mask
i lica....
r uxn:pop-byte
i lica....
r uxn:pop-byte
i lislor..
d 8
i lifean..
r uxn:address-mask
i listliju
r uxn:address
r uxn:memory-store

: uxn:memory-load
i lifelica
r uxn:address
r uxn:read-byte
i lifelicj
r uxn:short
r uxn:memory-load-short
i liju....
r uxn:push-byte

: uxn:memory-load-short
c (high-byte --)
i lisllife
d 8
r uxn:address
i liadlife
d 1
r uxn:address-mask
i anlica..
r uxn:read-byte
i orliju..
r uxn:push-short

: uxn:memory-store
i lica....
r uxn:pop-value
i lifelicj
r uxn:short
r uxn:memory-store-short
i lifeliju
r uxn:address
r uxn:write-byte

: uxn:memory-store-short
c (short --)
i dulisr..
d 8
i lifelica
r uxn:address
r uxn:write-byte
i lifeliad
r uxn:address
d 1
i lifean..
r uxn:address-mask
i liju....
r uxn:write-byte

: uxn:op-dei
i lica....
r uxn:pop-byte
i listlife
r uxn:address
r uxn:address
i lica....
r uxn:device-read
i lifelicj
r uxn:short
r uxn:dei-short
i liju....
r uxn:push-byte

: uxn:dei-short
c (high-byte --)
i lisllife
d 8
r uxn:address
i liadlica
d 1
r uxn:device-read
i orliju..
r uxn:push-short

: uxn:op-deo
i lica....
r uxn:pop-byte
i listlica
r uxn:address
r uxn:pop-value
i lifelicj
r uxn:short
r uxn:deo-short
i lifeliju
r uxn:address
r uxn:device-write

: uxn:deo-short
c (short --)
i dulisrli
d 8
r uxn:address
i felica..
r uxn:device-store
i lifeliad
r uxn:address
d 1
i liju....
r uxn:device-write

: uxn:op-add
i lica....
r uxn:pop-value
i lica....
r uxn:pop-value
i adliju..
r uxn:push-value

: uxn:op-sub
i lica....
r uxn:pop-value
i lica....
r uxn:pop-value
i swsuliju
r uxn:push-value

: uxn:op-and
i lica....
r uxn:pop-value
i lica....
r uxn:pop-value
i anliju..
r uxn:push-value

: uxn:op-ora
i lica....
r uxn:pop-value
i lica....
r uxn:pop-value
i orliju..
r uxn:push-value

: uxn:op-eor
i lica....
r uxn:pop-value
i lica....
r uxn:pop-value
i xoliju..
r uxn:push-value

: uxn:op-mul
c Split one operand into bytes to keep both partial products
c below 2^31. Only the low 16 product bits are needed. Restore
c address-stack temporaries before calling push-value.
i lica....
r uxn:pop-value
i lica....
r uxn:pop-value
i dulianpu
d 255
i lisrswdu
d 8
i pumulian
d 255
i lislpopo
d 8
i muadlian
d 65535
i liju....
r uxn:push-value

: uxn:op-div
i lica....
r uxn:pop-value
i lica....
r uxn:pop-value
i swdulieq
d 0
i licj....
r uxn:divide-zero
i diswdr..
i liju....
r uxn:push-value

: uxn:divide-zero
c (dividend divisor --)
i drdrli..
d 0
i liju....
r uxn:push-value

: uxn:op-sft
i lica....
r uxn:pop-byte
i lica....
r uxn:pop-value
i swdulisr
d 4
i puliansr
d 15
i poslliju
r uxn:push-value

: uxn:imm-table
c Base-zero opcodes bypass normal keep semantics.
r uxn:imm-brk
r uxn:imm-jci
r uxn:imm-jmi
r uxn:imm-jsi
r uxn:imm-lit
r uxn:imm-lit2
r uxn:imm-litr
r uxn:imm-lit2r

: uxn:imm-brk
i lilistre
d 0
r uxn:running

: uxn:imm-jci
i lica....
r uxn:pop-byte
i lica....
r uxn:immediate-offset
i swlicj..
r uxn:immediate-move
i drre....

: uxn:imm-jmi
i lica....
r uxn:immediate-offset
i liju....
r uxn:immediate-move

: uxn:imm-jsi
i lica....
r uxn:immediate-offset
i lilist..
r uxn:rsp
r uxn:ptr-address
i lilist..
r uxn:return-stack
r uxn:stack-base
i lifelica
r uxn:pc
r uxn:push-short
i liju....
r uxn:immediate-move

: uxn:immediate-offset
c (-- offset)
i lica....
r uxn:fetch
i lisllica
d 8
r uxn:fetch
i orre....

: uxn:immediate-move
c The post-operand PC is the base for immediate branches.
c (offset --)
i lifeadli
r uxn:pc
d 65535
i anlistre
r uxn:pc

: uxn:imm-lit
i lica....
r uxn:fetch
i liju....
r uxn:push-byte

: uxn:imm-lit2
i lica....
r uxn:fetch
i lica....
r uxn:push-byte
i lica....
r uxn:fetch
i liju....
r uxn:push-byte

: uxn:imm-litr
i lica....
r uxn:fetch
i liju....
r uxn:push-byte

: uxn:imm-lit2r
i lica....
r uxn:fetch
i lica....
r uxn:push-byte
i lica....
r uxn:fetch
i liju....
r uxn:push-byte

: uxn:code-end
c Debug marker for the end of code and dispatch tables.

: uxn:working-stack
* 256

: uxn:return-stack
* 256

: uxn:devices
* 256

: uxn:state
c State and scratch cells start here

: uxn:pc
d 256

: uxn:wsp
d 0

: uxn:rsp
d 0

: uxn:opcode
d 0

: uxn:short
d 0

: uxn:keep
d 0

: uxn:read-ptr
d 0

: uxn:stack-base
d 0

: uxn:address
d 0

: uxn:value
d 0

: uxn:block
d 0

: uxn:console-vector
d 0

: uxn:exit-status
d 0

: uxn:ptr-address
d 0

: uxn:running
d 0

: uxn:address-mask
d 0

: uxn:stderr-count
d 0

: uxn:stderr-block
d 64

: uxn:block-buffer
* 1024

: uxn:ram
~~~