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Pull generalised DIVU/DIVS into a macro.

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This commit is contained in:
Thomas Harte 2022-05-15 20:01:51 -04:00
parent 341bf2e480
commit acb63a1307
1 changed files with 31 additions and 64 deletions
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95
InstructionSets/M68k/Implementation/PerformImplementation.hpp
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@ -517,72 +517,39 @@ template <
Divisions.
*/
#define announce_divide_by_zero() \
status.negative_flag = status.overflow_flag = 0; \
status.zero_result = 1; \
flow_controller.raise_exception(Exception::IntegerDivideByZero)
#define DIV(Type16, Type32, flow_function) { \
status.carry_flag = 0; \
\
if(!src.w) { \
status.negative_flag = status.overflow_flag = 0; \
status.zero_result = 1; \
flow_controller.raise_exception(Exception::IntegerDivideByZero); \
return; \
} \
\
const auto dividend = Type32(dest.l); \
const auto divisor = Type32(Type16(src.w)); \
const auto quotient = dividend / divisor; \
\
if(quotient != Type32(Type16(quotient))) { \
status.overflow_flag = 1; \
flow_controller.template flow_function<true>(dividend, divisor); \
return; \
} \
\
const auto remainder = Type16(dividend % divisor); \
dest.l = uint32_t((uint32_t(remainder) << 16) | uint16_t(quotient)); \
\
status.overflow_flag = 0; \
status.zero_result = Status::FlagT(quotient); \
status.negative_flag = status.zero_result & 0x8000; \
flow_controller.template flow_function<false>(dividend, divisor); \
}
case Operation::DIVU: {
status.carry_flag = 0;
case Operation::DIVU: DIV(uint16_t, uint32_t, did_divu); break;
case Operation::DIVS: DIV(int16_t, int32_t, did_divs); break;
// An attempt to divide by zero schedules an exception.
if(!src.w) {
// Schedule a divide-by-zero exception.
announce_divide_by_zero();
return;
}
const auto dividend = uint32_t(dest.l);
const auto divisor = uint32_t(uint16_t(src.w));
const auto quotient = dividend / divisor;
// If overflow would occur, appropriate flags are set and the result is not written back.
if(quotient != uint16_t(quotient)) {
status.overflow_flag = 1;
flow_controller.template did_divu<true>(dividend, divisor);
return;
}
const auto remainder = uint16_t(dividend % divisor);
dest.l = uint32_t((remainder << 16) | uint16_t(quotient));
status.overflow_flag = 0;
status.zero_result = Status::FlagT(quotient);
status.negative_flag = status.zero_result & 0x8000;
flow_controller.template did_divu<false>(dividend, divisor);
} break;
case Operation::DIVS: {
status.carry_flag = 0;
// An attempt to divide by zero schedules an exception.
if(!src.w) {
// Schedule a divide-by-zero exception.
announce_divide_by_zero();
break;
}
const auto dividend = int32_t(dest.l);
const auto divisor = int32_t(int16_t(src.w));
const auto quotient = dividend / divisor;
// Check for overflow. If it exists, work here is already done.
if(quotient != int16_t(quotient)) {
status.overflow_flag = 1;
flow_controller.template did_divs<true>(dividend, divisor);
break;
}
const auto remainder = uint16_t(dividend % divisor);
dest.l = uint32_t((remainder << 16) | uint16_t(quotient));
status.overflow_flag = 0;
status.zero_result = Status::FlagT(quotient);
status.negative_flag = status.zero_result & 0x8000;
flow_controller.template did_divs<false>(dividend, divisor);
} break;
#undef announce_divide_by_zero
#undef DIV
// TRAP, which is a nicer form of ILLEGAL.
case Operation::TRAP: