; Simple 8 Bit Processor -*- Scheme -*-

(include "simplify.inc")

; FIXME: Delete sign extension of accumulator results.
; Sign extension is done when accumulator is read.

; define-arch must appear first

(define-arch
  (name proc) ; name of cpu family
  (comment "8 Bit Processor")
  (insn-lsb0? #f)
  (machs proc)
  (isas proc)
)

(define-isa
  (name proc)
  (default-insn-bitsize 8)
  (base-insn-bitsize 8)
  (default-insn-word-bitsize 8)
)

(define-cpu
  (name proc)
  (comment "8 Bit Processor Family")
  (endian big)
  (word-bitsize 8)
)

(define-mach
  (name proc)
  (comment "8 Bit FPGA Processor")
  (cpu proc)
)

(define-model
  (name proc)
  (comment "8 Bit Processor Model")
  (attrs)
  (mach proc)
  (unit u-exec "Execution Unit" () 1 1
	() () () ())
)

(dnf f-op        "op"                        ()   0  8)
(dnf f-uimm8     "unsigned 8 bit immediate"  ()   8  8)
(dnf f-uimm16    "unsigned 16 bit immediate" ()   8 16)

(define-normal-insn-enum
  insn-op "insn format enums" () OP_ f-op
  (.map .str (.iota 256))
)

(dnh h-pc "program counter" (PC PROFILE) (pc) () () ())

(define-hardware
  (name h-accu)
  (comment "Accumulator")
  (attrs PROFILE );CACHE-ADDR)
  (type register DI )
)

(define-attr
  (for operand)
  (type boolean)
  (name HASH-PREFIX)
  (comment "immediates have an optional '#' prefix")
)

(dnop accu     "accumulator"               () h-accu   f-nil)
(dnop uimm8    "unsigned 8 bit immediate"  () h-uint   f-uimm8)
(dnop uimm16   "unsigned 16 bit immediate" () h-uint   f-uimm16)


(dni nop "nop"
     ()
     "nop"
     (+ OP_0)
     (nop)
     ()
)

(dni lda "lda"
     ()
     "lda $uimm16"
     (+ OP_1 uimm16)
     (set accu (mem WI uimm16))
     ()
)

(dni ldc "ldc"
     ()
     "ldc $uimm8"
     (+ OP_2 uimm8)
     (set accu uimm8)
     ()
)

(dni decx "decx"
     ()
     "decx"
     (+ OP_100)
     (nop)
     ()
)

(dni decy "decy"
     ()
     "decy"
     (+ OP_101)
     (nop)
     ()
)