diff options
Diffstat (limited to 'arch/sh/kernel/cpu/sh2a/opcode_helper.c')
| -rw-r--r-- | arch/sh/kernel/cpu/sh2a/opcode_helper.c | 51 |
1 files changed, 51 insertions, 0 deletions
diff --git a/arch/sh/kernel/cpu/sh2a/opcode_helper.c b/arch/sh/kernel/cpu/sh2a/opcode_helper.c new file mode 100644 index 0000000000..c509081d90 --- /dev/null +++ b/arch/sh/kernel/cpu/sh2a/opcode_helper.c @@ -0,0 +1,51 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * arch/sh/kernel/cpu/sh2a/opcode_helper.c + * + * Helper for the SH-2A 32-bit opcodes. + * + * Copyright (C) 2007 Paul Mundt + */ +#include <linux/kernel.h> + +/* + * Instructions on SH are generally fixed at 16-bits, however, SH-2A + * introduces some 32-bit instructions. Since there are no real + * constraints on their use (and they can be mixed and matched), we need + * to check the instruction encoding to work out if it's a true 32-bit + * instruction or not. + * + * Presently, 32-bit opcodes have only slight variations in what the + * actual encoding looks like in the first-half of the instruction, which + * makes it fairly straightforward to differentiate from the 16-bit ones. + * + * First 16-bits of encoding Used by + * + * 0011nnnnmmmm0001 mov.b, mov.w, mov.l, fmov.d, + * fmov.s, movu.b, movu.w + * + * 0011nnnn0iii1001 bclr.b, bld.b, bset.b, bst.b, band.b, + * bandnot.b, bldnot.b, bor.b, bornot.b, + * bxor.b + * + * 0000nnnniiii0000 movi20 + * 0000nnnniiii0001 movi20s + */ +unsigned int instruction_size(unsigned int insn) +{ + /* Look for the common cases */ + switch ((insn & 0xf00f)) { + case 0x0000: /* movi20 */ + case 0x0001: /* movi20s */ + case 0x3001: /* 32-bit mov/fmov/movu variants */ + return 4; + } + + /* And the special cases.. */ + switch ((insn & 0xf08f)) { + case 0x3009: /* 32-bit b*.b bit operations */ + return 4; + } + + return 2; +} |