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One-byte-opcodes

X86-sahf

Signature
(x86-sahf 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-sahf

(defun x86-sahf (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-sahf))
  (declare (ignorable __function__))
  (b* ((?ctx 'x86-sahf))
   (b*
    (((the (unsigned-byte 16) ax)
      (rr16 0 x86))
     ((the (unsigned-byte 8) ah) (ash ax -8))
     ((the (unsigned-byte 32) rflags)
      (rflags x86))
     (cf (rflagsbits->cf ah))
     (pf (rflagsbits->pf ah))
     (af (rflagsbits->af ah))
     (zf (rflagsbits->zf ah))
     (sf (rflagsbits->sf ah))
     ((the (unsigned-byte 32) new-rflags)
      (!rflagsbits->cf
       cf
       (!rflagsbits->pf
           pf
           (!rflagsbits->af
                af
                (!rflagsbits->zf zf (!rflagsbits->sf sf rflags))))))
     (x86 (!rflags new-rflags x86))
     (x86 (write-*ip proc-mode temp-rip x86)))
    x86))))

Theorem: x86p-of-x86-sahf

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