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pdp10-opcodes: add pdp10_instruction_from_high13() helper for decoding/disassembly

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Mikael Pettersson 2013-07-16 16:52:22 +00:00
parent 8f37f6155e
commit 0a39fd1237
2 changed files with 28 additions and 0 deletions
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2
include/pdp10-opcodes.h
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@ -130,4 +130,6 @@ extern const unsigned int pdp10_num_aliases;
extern const struct pdp10_instruction pdp10_extended_instruction[];
extern const unsigned int pdp10_num_extended_instructions;
const struct pdp10_instruction *pdp10_instruction_from_high13(unsigned int high13);
#endif /* PDP10_OPCODES_H */

26
lib/pdp10-opcodes.c
View File

@ -957,3 +957,29 @@ const struct pdp10_instruction pdp10_extended_instruction[] =
const unsigned int pdp10_num_extended_instructions =
sizeof pdp10_extended_instruction / sizeof pdp10_extended_instruction[0];
static int pdp10_opcode_matches(unsigned int high13, const struct pdp10_instruction *insn)
{
unsigned int opcode;
if ((insn->type & PDP10_A_OPCODE) || (insn->type & PDP10_IO))
opcode = high13 << 2; /* table entry has 5 octal digits == 15 bits */
else
opcode = high13 >> 4; /* table entry has 3 octal digits == 9 bits */
return opcode == insn->opcode;
}
const struct pdp10_instruction *pdp10_instruction_from_high13(unsigned int high13)
{
unsigned int i;
for (i = 0; i < pdp10_num_aliases; ++i)
if (pdp10_opcode_matches(high13, &pdp10_alias[i]))
return &pdp10_alias[i];
for (i = 0; i < pdp10_num_instructions; ++i)
if (pdp10_opcode_matches(high13, &pdp10_instruction[i]))
return &pdp10_instruction[i];
return (void*)0;
}