mirror of
https://github.com/superseriousbusiness/gotosocial.git
synced 2024-11-25 02:35:57 +03:00
257 lines
6.2 KiB
Go
257 lines
6.2 KiB
Go
// Copyright 2015 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// This file encapsulates some of the odd characteristics of the ARM
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// instruction set, to minimize its interaction with the core of the
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// assembler.
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package arch
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import (
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"strings"
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"github.com/twitchyliquid64/golang-asm/obj"
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"github.com/twitchyliquid64/golang-asm/obj/arm"
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)
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var armLS = map[string]uint8{
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"U": arm.C_UBIT,
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"S": arm.C_SBIT,
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"W": arm.C_WBIT,
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"P": arm.C_PBIT,
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"PW": arm.C_WBIT | arm.C_PBIT,
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"WP": arm.C_WBIT | arm.C_PBIT,
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}
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var armSCOND = map[string]uint8{
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"EQ": arm.C_SCOND_EQ,
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"NE": arm.C_SCOND_NE,
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"CS": arm.C_SCOND_HS,
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"HS": arm.C_SCOND_HS,
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"CC": arm.C_SCOND_LO,
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"LO": arm.C_SCOND_LO,
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"MI": arm.C_SCOND_MI,
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"PL": arm.C_SCOND_PL,
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"VS": arm.C_SCOND_VS,
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"VC": arm.C_SCOND_VC,
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"HI": arm.C_SCOND_HI,
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"LS": arm.C_SCOND_LS,
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"GE": arm.C_SCOND_GE,
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"LT": arm.C_SCOND_LT,
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"GT": arm.C_SCOND_GT,
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"LE": arm.C_SCOND_LE,
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"AL": arm.C_SCOND_NONE,
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"U": arm.C_UBIT,
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"S": arm.C_SBIT,
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"W": arm.C_WBIT,
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"P": arm.C_PBIT,
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"PW": arm.C_WBIT | arm.C_PBIT,
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"WP": arm.C_WBIT | arm.C_PBIT,
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"F": arm.C_FBIT,
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"IBW": arm.C_WBIT | arm.C_PBIT | arm.C_UBIT,
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"IAW": arm.C_WBIT | arm.C_UBIT,
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"DBW": arm.C_WBIT | arm.C_PBIT,
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"DAW": arm.C_WBIT,
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"IB": arm.C_PBIT | arm.C_UBIT,
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"IA": arm.C_UBIT,
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"DB": arm.C_PBIT,
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"DA": 0,
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}
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var armJump = map[string]bool{
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"B": true,
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"BL": true,
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"BX": true,
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"BEQ": true,
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"BNE": true,
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"BCS": true,
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"BHS": true,
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"BCC": true,
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"BLO": true,
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"BMI": true,
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"BPL": true,
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"BVS": true,
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"BVC": true,
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"BHI": true,
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"BLS": true,
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"BGE": true,
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"BLT": true,
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"BGT": true,
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"BLE": true,
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"CALL": true,
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"JMP": true,
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}
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func jumpArm(word string) bool {
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return armJump[word]
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}
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// IsARMCMP reports whether the op (as defined by an arm.A* constant) is
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// one of the comparison instructions that require special handling.
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func IsARMCMP(op obj.As) bool {
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switch op {
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case arm.ACMN, arm.ACMP, arm.ATEQ, arm.ATST:
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return true
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}
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return false
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}
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// IsARMSTREX reports whether the op (as defined by an arm.A* constant) is
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// one of the STREX-like instructions that require special handling.
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func IsARMSTREX(op obj.As) bool {
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switch op {
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case arm.ASTREX, arm.ASTREXD, arm.ASWPW, arm.ASWPBU:
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return true
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}
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return false
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}
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// MCR is not defined by the obj/arm; instead we define it privately here.
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// It is encoded as an MRC with a bit inside the instruction word,
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// passed to arch.ARMMRCOffset.
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const aMCR = arm.ALAST + 1
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// IsARMMRC reports whether the op (as defined by an arm.A* constant) is
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// MRC or MCR
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func IsARMMRC(op obj.As) bool {
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switch op {
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case arm.AMRC, aMCR: // Note: aMCR is defined in this package.
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return true
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}
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return false
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}
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// IsARMBFX reports whether the op (as defined by an arm.A* constant) is one the
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// BFX-like instructions which are in the form of "op $width, $LSB, (Reg,) Reg".
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func IsARMBFX(op obj.As) bool {
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switch op {
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case arm.ABFX, arm.ABFXU, arm.ABFC, arm.ABFI:
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return true
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}
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return false
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}
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// IsARMFloatCmp reports whether the op is a floating comparison instruction.
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func IsARMFloatCmp(op obj.As) bool {
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switch op {
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case arm.ACMPF, arm.ACMPD:
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return true
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}
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return false
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}
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// ARMMRCOffset implements the peculiar encoding of the MRC and MCR instructions.
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// The difference between MRC and MCR is represented by a bit high in the word, not
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// in the usual way by the opcode itself. Asm must use AMRC for both instructions, so
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// we return the opcode for MRC so that asm doesn't need to import obj/arm.
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func ARMMRCOffset(op obj.As, cond string, x0, x1, x2, x3, x4, x5 int64) (offset int64, op0 obj.As, ok bool) {
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op1 := int64(0)
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if op == arm.AMRC {
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op1 = 1
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}
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bits, ok := ParseARMCondition(cond)
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if !ok {
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return
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}
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offset = (0xe << 24) | // opcode
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(op1 << 20) | // MCR/MRC
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((int64(bits) ^ arm.C_SCOND_XOR) << 28) | // scond
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((x0 & 15) << 8) | //coprocessor number
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((x1 & 7) << 21) | // coprocessor operation
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((x2 & 15) << 12) | // ARM register
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((x3 & 15) << 16) | // Crn
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((x4 & 15) << 0) | // Crm
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((x5 & 7) << 5) | // coprocessor information
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(1 << 4) /* must be set */
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return offset, arm.AMRC, true
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}
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// IsARMMULA reports whether the op (as defined by an arm.A* constant) is
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// MULA, MULS, MMULA, MMULS, MULABB, MULAWB or MULAWT, the 4-operand instructions.
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func IsARMMULA(op obj.As) bool {
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switch op {
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case arm.AMULA, arm.AMULS, arm.AMMULA, arm.AMMULS, arm.AMULABB, arm.AMULAWB, arm.AMULAWT:
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return true
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}
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return false
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}
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var bcode = []obj.As{
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arm.ABEQ,
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arm.ABNE,
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arm.ABCS,
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arm.ABCC,
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arm.ABMI,
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arm.ABPL,
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arm.ABVS,
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arm.ABVC,
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arm.ABHI,
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arm.ABLS,
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arm.ABGE,
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arm.ABLT,
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arm.ABGT,
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arm.ABLE,
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arm.AB,
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obj.ANOP,
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}
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// ARMConditionCodes handles the special condition code situation for the ARM.
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// It returns a boolean to indicate success; failure means cond was unrecognized.
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func ARMConditionCodes(prog *obj.Prog, cond string) bool {
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if cond == "" {
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return true
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}
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bits, ok := ParseARMCondition(cond)
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if !ok {
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return false
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}
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/* hack to make B.NE etc. work: turn it into the corresponding conditional */
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if prog.As == arm.AB {
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prog.As = bcode[(bits^arm.C_SCOND_XOR)&0xf]
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bits = (bits &^ 0xf) | arm.C_SCOND_NONE
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}
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prog.Scond = bits
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return true
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}
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// ParseARMCondition parses the conditions attached to an ARM instruction.
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// The input is a single string consisting of period-separated condition
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// codes, such as ".P.W". An initial period is ignored.
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func ParseARMCondition(cond string) (uint8, bool) {
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return parseARMCondition(cond, armLS, armSCOND)
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}
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func parseARMCondition(cond string, ls, scond map[string]uint8) (uint8, bool) {
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cond = strings.TrimPrefix(cond, ".")
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if cond == "" {
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return arm.C_SCOND_NONE, true
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}
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names := strings.Split(cond, ".")
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bits := uint8(0)
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for _, name := range names {
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if b, present := ls[name]; present {
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bits |= b
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continue
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}
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if b, present := scond[name]; present {
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bits = (bits &^ arm.C_SCOND) | b
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continue
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}
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return 0, false
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}
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return bits, true
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}
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func armRegisterNumber(name string, n int16) (int16, bool) {
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if n < 0 || 15 < n {
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return 0, false
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}
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switch name {
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case "R":
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return arm.REG_R0 + n, true
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case "F":
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return arm.REG_F0 + n, true
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}
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return 0, false
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}
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