diff options
Diffstat (limited to 'vendor/golang.org/x/arch/arm/armasm/plan9x.go')
| -rw-r--r-- | vendor/golang.org/x/arch/arm/armasm/plan9x.go | 215 |
1 files changed, 215 insertions, 0 deletions
diff --git a/vendor/golang.org/x/arch/arm/armasm/plan9x.go b/vendor/golang.org/x/arch/arm/armasm/plan9x.go new file mode 100644 index 00000000..d43cc963 --- /dev/null +++ b/vendor/golang.org/x/arch/arm/armasm/plan9x.go @@ -0,0 +1,215 @@ +// Copyright 2014 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package armasm + +import ( + "bytes" + "encoding/binary" + "fmt" + "io" + "strings" +) + +// GoSyntax returns the Go assembler syntax for the instruction. +// The syntax was originally defined by Plan 9. +// The pc is the program counter of the instruction, used for expanding +// PC-relative addresses into absolute ones. +// The symname function queries the symbol table for the program +// being disassembled. Given a target address it returns the name and base +// address of the symbol containing the target, if any; otherwise it returns "", 0. +// The reader r should read from the text segment using text addresses +// as offsets; it is used to display pc-relative loads as constant loads. +func GoSyntax(inst Inst, pc uint64, symname func(uint64) (string, uint64), text io.ReaderAt) string { + if symname == nil { + symname = func(uint64) (string, uint64) { return "", 0 } + } + + var args []string + for _, a := range inst.Args { + if a == nil { + break + } + args = append(args, plan9Arg(&inst, pc, symname, a)) + } + + op := inst.Op.String() + + switch inst.Op &^ 15 { + case LDR_EQ, LDRB_EQ, LDRH_EQ: + // Check for RET + reg, _ := inst.Args[0].(Reg) + mem, _ := inst.Args[1].(Mem) + if inst.Op&^15 == LDR_EQ && reg == R15 && mem.Base == SP && mem.Sign == 0 && mem.Mode == AddrPostIndex { + return fmt.Sprintf("RET%s #%d", op[3:], mem.Offset) + } + + // Check for PC-relative load. + if mem.Base == PC && mem.Sign == 0 && mem.Mode == AddrOffset && text != nil { + addr := uint32(pc) + 8 + uint32(mem.Offset) + buf := make([]byte, 4) + switch inst.Op &^ 15 { + case LDRB_EQ: + if _, err := text.ReadAt(buf[:1], int64(addr)); err != nil { + break + } + args[1] = fmt.Sprintf("$%#x", buf[0]) + + case LDRH_EQ: + if _, err := text.ReadAt(buf[:2], int64(addr)); err != nil { + break + } + args[1] = fmt.Sprintf("$%#x", binary.LittleEndian.Uint16(buf)) + + case LDR_EQ: + if _, err := text.ReadAt(buf, int64(addr)); err != nil { + break + } + x := binary.LittleEndian.Uint32(buf) + if s, base := symname(uint64(x)); s != "" && uint64(x) == base { + args[1] = fmt.Sprintf("$%s(SB)", s) + } else { + args[1] = fmt.Sprintf("$%#x", x) + } + } + } + } + + // Move addressing mode into opcode suffix. + suffix := "" + switch inst.Op &^ 15 { + case LDR_EQ, LDRB_EQ, LDRH_EQ, STR_EQ, STRB_EQ, STRH_EQ: + mem, _ := inst.Args[1].(Mem) + switch mem.Mode { + case AddrOffset, AddrLDM: + // no suffix + case AddrPreIndex, AddrLDM_WB: + suffix = ".W" + case AddrPostIndex: + suffix = ".P" + } + off := "" + if mem.Offset != 0 { + off = fmt.Sprintf("%#x", mem.Offset) + } + base := fmt.Sprintf("(R%d)", int(mem.Base)) + index := "" + if mem.Sign != 0 { + sign := "" + if mem.Sign < 0 { + sign = "" + } + shift := "" + if mem.Count != 0 { + shift = fmt.Sprintf("%s%d", plan9Shift[mem.Shift], mem.Count) + } + index = fmt.Sprintf("(%sR%d%s)", sign, int(mem.Index), shift) + } + args[1] = off + base + index + } + + // Reverse args, placing dest last. + for i, j := 0, len(args)-1; i < j; i, j = i+1, j-1 { + args[i], args[j] = args[j], args[i] + } + + switch inst.Op &^ 15 { + case MOV_EQ: + op = "MOVW" + op[3:] + + case LDR_EQ: + op = "MOVW" + op[3:] + suffix + case LDRB_EQ: + op = "MOVB" + op[4:] + suffix + case LDRH_EQ: + op = "MOVH" + op[4:] + suffix + + case STR_EQ: + op = "MOVW" + op[3:] + suffix + args[0], args[1] = args[1], args[0] + case STRB_EQ: + op = "MOVB" + op[4:] + suffix + args[0], args[1] = args[1], args[0] + case STRH_EQ: + op = "MOVH" + op[4:] + suffix + args[0], args[1] = args[1], args[0] + } + + if args != nil { + op += " " + strings.Join(args, ", ") + } + + return op +} + +// assembler syntax for the various shifts. +// @x> is a lie; the assembler uses @> 0 +// instead of @x> 1, but i wanted to be clear that it +// was a different operation (rotate right extended, not rotate right). +var plan9Shift = []string{"<<", ">>", "->", "@>", "@x>"} + +func plan9Arg(inst *Inst, pc uint64, symname func(uint64) (string, uint64), arg Arg) string { + switch a := arg.(type) { + case Endian: + + case Imm: + return fmt.Sprintf("$%d", int(a)) + + case Mem: + + case PCRel: + addr := uint32(pc) + 8 + uint32(a) + if s, base := symname(uint64(addr)); s != "" && uint64(addr) == base { + return fmt.Sprintf("%s(SB)", s) + } + return fmt.Sprintf("%#x", addr) + + case Reg: + if a < 16 { + return fmt.Sprintf("R%d", int(a)) + } + + case RegList: + var buf bytes.Buffer + start := -2 + end := -2 + fmt.Fprintf(&buf, "[") + flush := func() { + if start >= 0 { + if buf.Len() > 1 { + fmt.Fprintf(&buf, ",") + } + if start == end { + fmt.Fprintf(&buf, "R%d", start) + } else { + fmt.Fprintf(&buf, "R%d-R%d", start, end) + } + start = -2 + end = -2 + } + } + for i := 0; i < 16; i++ { + if a&(1<<uint(i)) != 0 { + if i == end+1 { + end++ + continue + } + start = i + end = i + } else { + flush() + } + } + flush() + fmt.Fprintf(&buf, "]") + return buf.String() + + case RegShift: + return fmt.Sprintf("R%d%s$%d", int(a.Reg), plan9Shift[a.Shift], int(a.Count)) + + case RegShiftReg: + return fmt.Sprintf("R%d%sR%d", int(a.Reg), plan9Shift[a.Shift], int(a.RegCount)) + } + return strings.ToUpper(arg.String()) +} |