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Semantics64

Exec64-lb

Semantics of the LB instruction [ISA:2.6].

Signature
(exec64-lb rd rs1 imm stat) → new-stat
Arguments: rd — Guard (ubyte5p rd).; rs1 — Guard (ubyte5p rs1).; imm — Guard (ubyte12p imm).; stat — Guard (state64p stat).
Returns: new-stat — Type (state64p new-stat).

We calculate the effective address. We read an unsigned 8-bit integer from the effective address, and sign-extend it to 64 bits. We write the result to rd. We increment the program counter.

Definitions and Theorems

Function: exec64-lb

(defun exec64-lb (rd rs1 imm stat)
  (declare (xargs :guard (and (ubyte5p rd)
                              (ubyte5p rs1)
                              (ubyte12p imm)
                              (state64p stat))))
  (let ((__function__ 'exec64-lb))
    (declare (ignorable __function__))
    (b* ((addr (eff64-addr rs1 imm stat))
         (result (loghead 64
                          (logext 8 (read64-mem-ubyte8 addr stat))))
         (stat (write64-xreg rd result stat))
         (stat (inc64-pc stat)))
      stat)))

Theorem: state64p-of-exec64-lb

(defthm state64p-of-exec64-lb
  (b* ((new-stat (exec64-lb rd rs1 imm stat)))
    (state64p new-stat))
  :rule-classes :rewrite)

Theorem: exec64-lb-of-ubyte5-fix-rd

(defthm exec64-lb-of-ubyte5-fix-rd
  (equal (exec64-lb (ubyte5-fix rd) rs1 imm stat)
         (exec64-lb rd rs1 imm stat)))

Theorem: exec64-lb-ubyte5-equiv-congruence-on-rd

(defthm exec64-lb-ubyte5-equiv-congruence-on-rd
  (implies (ubyte5-equiv rd rd-equiv)
           (equal (exec64-lb rd rs1 imm stat)
                  (exec64-lb rd-equiv rs1 imm stat)))
  :rule-classes :congruence)

Theorem: exec64-lb-of-ubyte5-fix-rs1

(defthm exec64-lb-of-ubyte5-fix-rs1
  (equal (exec64-lb rd (ubyte5-fix rs1) imm stat)
         (exec64-lb rd rs1 imm stat)))

Theorem: exec64-lb-ubyte5-equiv-congruence-on-rs1

(defthm exec64-lb-ubyte5-equiv-congruence-on-rs1
  (implies (ubyte5-equiv rs1 rs1-equiv)
           (equal (exec64-lb rd rs1 imm stat)
                  (exec64-lb rd rs1-equiv imm stat)))
  :rule-classes :congruence)

Theorem: exec64-lb-of-ubyte12-fix-imm

(defthm exec64-lb-of-ubyte12-fix-imm
  (equal (exec64-lb rd rs1 (ubyte12-fix imm)
                    stat)
         (exec64-lb rd rs1 imm stat)))

Theorem: exec64-lb-ubyte12-equiv-congruence-on-imm

(defthm exec64-lb-ubyte12-equiv-congruence-on-imm
  (implies (acl2::ubyte12-equiv imm imm-equiv)
           (equal (exec64-lb rd rs1 imm stat)
                  (exec64-lb rd rs1 imm-equiv stat)))
  :rule-classes :congruence)

Theorem: exec64-lb-of-state64-fix-stat

(defthm exec64-lb-of-state64-fix-stat
  (equal (exec64-lb rd rs1 imm (state64-fix stat))
         (exec64-lb rd rs1 imm stat)))

Theorem: exec64-lb-state64-equiv-congruence-on-stat

(defthm exec64-lb-state64-equiv-congruence-on-stat
  (implies (state64-equiv stat stat-equiv)
           (equal (exec64-lb rd rs1 imm stat)
                  (exec64-lb rd rs1 imm stat-equiv)))
  :rule-classes :congruence)