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Two-byte-opcodes

X86-bsr

Signature
(x86-bsr proc-mode start-rip temp-rip prefixes rex-byte opcode modr/m sib x86) → x86
Returns: x86 — Type (x86p x86), given (x86p x86).

Definitions and Theorems

Function: x86-bsr

(defun x86-bsr (proc-mode start-rip temp-rip
                          prefixes rex-byte opcode modr/m sib x86)
 (declare (xargs :stobjs (x86)))
 (declare (type (integer 0 4) proc-mode)
          (type (signed-byte 48) start-rip)
          (type (signed-byte 48) temp-rip)
          (type (unsigned-byte 52) prefixes)
          (type (unsigned-byte 8) rex-byte)
          (type (unsigned-byte 8) opcode)
          (type (unsigned-byte 8) modr/m)
          (type (unsigned-byte 8) sib))
 (declare (ignorable proc-mode start-rip temp-rip
                     prefixes rex-byte opcode modr/m sib))
 (declare (xargs :guard (and (prefixes-p prefixes)
                             (modr/m-p modr/m)
                             (sib-p sib)
                             (rip-guard-okp proc-mode temp-rip))))
 (let ((__function__ 'x86-bsr))
  (declare (ignorable __function__))
  (b* ((?ctx 'x86-bsr)
       (?r/m (the (unsigned-byte 3)
                  (modr/m->r/m modr/m)))
       (?mod (the (unsigned-byte 2)
                  (modr/m->mod modr/m)))
       (?reg (the (unsigned-byte 3)
                  (modr/m->reg modr/m))))
   (b*
    (((the (integer 1 8) operand-size)
      (select-operand-size proc-mode nil
                           rex-byte nil prefixes nil nil nil x86))
     (p2 (prefixes->seg prefixes))
     (p4? (equal 103 (prefixes->adr prefixes)))
     (seg-reg
         (select-segment-register proc-mode p2 p4? mod r/m sib x86))
     (inst-ac? t)
     ((mv flg0 source
          (the (unsigned-byte 3) increment-rip-by)
          (the (signed-byte 64) addr)
          x86)
      (x86-operand-from-modr/m-and-sib-bytes
           proc-mode
           0 operand-size inst-ac? nil seg-reg p4?
           temp-rip rex-byte r/m mod sib 0 x86))
     ((when flg0)
      (!!ms-fresh :x86-operand-from-modr/m-and-sib-bytes flg0))
     ((mv flg (the (signed-byte 48) temp-rip))
      (add-to-*ip proc-mode
                  temp-rip increment-rip-by x86))
     ((when flg)
      (!!ms-fresh :rip-increment-error temp-rip))
     (badlength? (check-instruction-length start-rip temp-rip 0))
     ((when badlength?)
      (!!fault-fresh :gp 0
                     :instruction-length badlength?))
     (x86 (if (equal source 0)
              x86
            (!rgfi-size operand-size
                        (reg-index reg rex-byte *r*)
                        (bsr source)
                        rex-byte x86)))
     (x86 (let* ((x86 (!flgi :zf (if (equal source 0) 1 0)
                             x86))
                 (x86 (!flgi-undefined :cf x86))
                 (x86 (!flgi-undefined :pf x86))
                 (x86 (!flgi-undefined :af x86))
                 (x86 (!flgi-undefined :sf x86))
                 (x86 (!flgi-undefined :of x86)))
            x86))
     (x86 (write-*ip proc-mode temp-rip x86)))
    x86))))

Theorem: x86p-of-x86-bsr

(defthm x86p-of-x86-bsr
  (implies (x86p x86)
           (b* ((x86 (x86-bsr proc-mode start-rip temp-rip prefixes
                              rex-byte opcode modr/m sib x86)))
             (x86p x86)))
  :rule-classes :rewrite)