// SPDX-License-Identifier: GPL-2.0-only
/*
 *  linux/arch/arm/kernel/opcodes.c
 *
 *  A32 condition code lookup feature moved from nwfpe/fpopcode.c
 */

#include <linux/module.h>
#include <asm/opcodes.h>

#define ARM_OPCODE_CONDITION_UNCOND 0xf

/*
 * condition code lookup table
 * index into the table is test code: EQ, NE, ... LT, GT, AL, NV
 *
 * bit position in short is condition code: NZCV
 */
static const unsigned short cc_map[16] = {
        0xF0F0,                 /* EQ == Z set            */
        0x0F0F,                 /* NE                     */
        0xCCCC,                 /* CS == C set            */
        0x3333,                 /* CC                     */
        0xFF00,                 /* MI == N set            */
        0x00FF,                 /* PL                     */
        0xAAAA,                 /* VS == V set            */
        0x5555,                 /* VC                     */
        0x0C0C,                 /* HI == C set && Z clear */
        0xF3F3,                 /* LS == C clear || Z set */
        0xAA55,                 /* GE == (N==V)           */
        0x55AA,                 /* LT == (N!=V)           */
        0x0A05,                 /* GT == (!Z && (N==V))   */
        0xF5FA,                 /* LE == (Z || (N!=V))    */
        0xFFFF,                 /* AL always              */
        0                       /* NV                     */
};

/*
 * Returns:
 * ARM_OPCODE_CONDTEST_FAIL   - if condition fails
 * ARM_OPCODE_CONDTEST_PASS   - if condition passes (including AL)
 * ARM_OPCODE_CONDTEST_UNCOND - if NV condition, or separate unconditional
 *                              opcode space from v5 onwards
 *
 * Code that tests whether a conditional instruction would pass its condition
 * check should check that return value == ARM_OPCODE_CONDTEST_PASS.
 *
 * Code that tests if a condition means that the instruction would be executed
 * (regardless of conditional or unconditional) should instead check that the
 * return value != ARM_OPCODE_CONDTEST_FAIL.
 */
asmlinkage unsigned int arm_check_condition(u32 opcode, u32 psr)
{
        u32 cc_bits  = opcode >> 28;
        u32 psr_cond = psr >> 28;
        unsigned int ret;

        if (cc_bits != ARM_OPCODE_CONDITION_UNCOND) {
                if ((cc_map[cc_bits] >> (psr_cond)) & 1)
                        ret = ARM_OPCODE_CONDTEST_PASS;
                else
                        ret = ARM_OPCODE_CONDTEST_FAIL;
        } else {
                ret = ARM_OPCODE_CONDTEST_UNCOND;
        }

        return ret;
}
EXPORT_SYMBOL_GPL(arm_check_condition);