		Search-engine friendly clone of the ACL2 documentation.

Semantics64

Exec64-srliw

Semantics of the SRLIW instruction [ISA:4.2.1].

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

We read an unsigned 32-bit integer from rs1. The immediate is the shift amount, from 0 to 31. We shift the integer right by the shift amount; this is a logical shift, because the integer is unsigned. We write the result to rd, as a signed 32-bit integer. We increment the program counter.

Definitions and Theorems

Function: exec64-srliw

(defun exec64-srliw (rd rs1 imm stat)
  (declare (xargs :guard (and (ubyte5p rd)
                              (ubyte5p rs1)
                              (ubyte5p imm)
                              (state64p stat))))
  (let ((__function__ 'exec64-srliw))
    (declare (ignorable __function__))
    (b* ((rs1-operand (read64-xreg-unsigned32 rs1 stat))
         (shift-amount (ubyte5-fix imm))
         (result (ash rs1-operand (- shift-amount)))
         (stat (write64-xreg-32 rd result stat))
         (stat (inc64-pc stat)))
      stat)))

Theorem: state64p-of-exec64-srliw

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

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

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

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

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

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

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

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

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

Theorem: exec64-srliw-of-ubyte5-fix-imm

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

Theorem: exec64-srliw-ubyte5-equiv-congruence-on-imm

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

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

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

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

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