;;;; object-uword-ref.scm
;;;; Kon Lovett, Mar '20

(cond-expand
  (64bit
    (define-constant WORD-SIZE (/ 64 8)) )
  (else
    (define-constant WORD-SIZE (/ 32 8)) ) )

(: blob-word-ref (blob fixnum --> integer))

;;

;NOTE datum allocation on "word" boundary (at least)
;
;NOTE `byts' type is "weaker" here than the Scheme type, `blob' only, mainly due to
;ease of implementation.
;
(cond-expand
  (64bit
    (define blob-word-ref
      (foreign-lambda* unsigned-integer64 (((nonnull-scheme-pointer unsigned-byte) byts) (unsigned-integer64 off)) "
        return( *(uint64_t *)(&byts[off]) );")) )
  (else
    (define blob-word-ref
      (foreign-lambda* unsigned-integer32 (((nonnull-scheme-pointer unsigned-byte) byts) (unsigned-integer32 off)) "
        return( *(uint32_t *)(&byts[off]) );")) ) )

(define-constant C_WORD_SIZE WORD-SIZE)

(define-inline (object-uword-ref proc #!optional (idx 0))
  ;skip over C_WORD header
  (blob-word-ref (object->pointer proc) (* C_WORD_SIZE (add1 idx))) )