56 lines
1.5 KiB
C
56 lines
1.5 KiB
C
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/*
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* arch/sh/kernel/cpu/sh2a/opcode_helper.c
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*
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* Helper for the SH-2A 32-bit opcodes.
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*
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* Copyright (C) 2007 Paul Mundt
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*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*/
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#include <linux/kernel.h>
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#include <asm/system.h>
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/*
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* Instructions on SH are generally fixed at 16-bits, however, SH-2A
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* introduces some 32-bit instructions. Since there are no real
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* constraints on their use (and they can be mixed and matched), we need
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* to check the instruction encoding to work out if it's a true 32-bit
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* instruction or not.
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*
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* Presently, 32-bit opcodes have only slight variations in what the
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* actual encoding looks like in the first-half of the instruction, which
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* makes it fairly straightforward to differentiate from the 16-bit ones.
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*
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* First 16-bits of encoding Used by
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*
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* 0011nnnnmmmm0001 mov.b, mov.w, mov.l, fmov.d,
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* fmov.s, movu.b, movu.w
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*
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* 0011nnnn0iii1001 bclr.b, bld.b, bset.b, bst.b, band.b,
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* bandnot.b, bldnot.b, bor.b, bornot.b,
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* bxor.b
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*
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* 0000nnnniiii0000 movi20
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* 0000nnnniiii0001 movi20s
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*/
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unsigned int instruction_size(unsigned int insn)
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{
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/* Look for the common cases */
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switch ((insn & 0xf00f)) {
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case 0x0000: /* movi20 */
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case 0x0001: /* movi20s */
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case 0x3001: /* 32-bit mov/fmov/movu variants */
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return 4;
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}
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/* And the special cases.. */
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switch ((insn & 0xf08f)) {
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case 0x3009: /* 32-bit b*.b bit operations */
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return 4;
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}
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return 2;
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}
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