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Fill in comments, eliminate u/s_extend16 macros.

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Thomas Harte 2022-10-17 15:37:13 -04:00
parent f095bba1ca
commit 8148397f62
1 changed files with 22 additions and 7 deletions
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29
InstructionSets/M68k/Implementation/PerformImplementation.hpp
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@ -17,8 +17,11 @@
namespace InstructionSet {
namespace M68k {
#define u_extend16(x) uint32_t(int16_t(x))
#define s_extend16(x) int32_t(int16_t(x))
/// Sign-extend @c x to 32 bits and return as an unsigned 32-bit int.
inline uint32_t u_extend16(uint16_t x) { return uint32_t(int16_t(x)); }
/// Sign-extend @c x to 32 bits and return as a signed 32-bit int.
inline int32_t s_extend16(uint16_t x) { return int32_t(int16_t(x)); }
namespace Primitive {
@ -71,6 +74,10 @@ static void add_sub(IntT source, IntT &destination, Status &status) {
destination = result;
}
/// Perform an SBCD of @c lhs - @c rhs, storing the result to @c destination and updating @c status.
///
/// @discussion The slightly awkward abandonment of source, destination permits the use of this for both
/// SBCD and NBCD.
inline void sbcd(uint8_t rhs, uint8_t lhs, uint8_t &destination, Status &status) {
const int extend = (status.extend_flag ? 1 : 0);
const int unadjusted_result = lhs - rhs - extend;
@ -93,6 +100,8 @@ inline void sbcd(uint8_t rhs, uint8_t lhs, uint8_t &destination, Status &status)
status.overflow_flag = unadjusted_result & ~result & 0x80;
}
/// Perform the bitwise operation defined by @c operation on @c source and @c destination and update @c status.
/// Bitwise operations are any of the byte, word or long versions of AND, OR and EOR.
template <Operation operation, typename IntT>
void bitwise(IntT source, IntT &destination, Status &status) {
static_assert(
@ -118,7 +127,7 @@ void bitwise(IntT source, IntT &destination, Status &status) {
status.negative_flag = destination & top_bit<IntT>();
}
/// Performs a compare of @c source to @c destination, setting zero, carry, negative and overflow flags.
/// Compare of @c source to @c destination, setting zero, carry, negative and overflow flags.
template <typename IntT>
void compare(IntT source, IntT destination, Status &status) {
const IntT result = destination - source;
@ -134,7 +143,7 @@ inline uint32_t mask_bit(const Preinstruction &instruction, uint32_t source) {
return source & (instruction.mode<1>() == AddressingMode::DataRegisterDirect ? 31 : 7);
}
/// Performs a BCLR, BCHG or BSET as specified by @c operation and described by @c instruction, @c source and @c destination, updating @c destination and @c status.
/// Perform a BCLR, BCHG or BSET as specified by @c operation and described by @c instruction, @c source and @c destination, updating @c destination and @c status.
/// Also makes an appropriate notification to the @c flow_controller.
template <Operation operation, typename FlowController>
void bit_manipulate(const Preinstruction &instruction, uint32_t source, uint32_t &destination, Status &status, FlowController &flow_controller) {
@ -159,6 +168,7 @@ template <typename IntT> void clear(IntT &destination, Status &status) {
status.negative_flag = status.overflow_flag = status.carry_flag = status.zero_result = 0;
}
/// Perform an ANDI, EORI or ORI to either SR or CCR, notifying @c flow_controller if appropriate.
template <Operation operation, typename FlowController>
void apply_sr_ccr(uint16_t source, Status &status, FlowController &flow_controller) {
static_assert(
@ -196,6 +206,7 @@ void apply_sr_ccr(uint16_t source, Status &status, FlowController &flow_controll
}
}
/// Perform a MULU or MULS between @c source and @c destination, updating @c status and notifying @c flow_controller.
template <bool is_mulu, typename FlowController>
void multiply(uint16_t source, uint32_t &destination, Status &status, FlowController &flow_controller) {
if constexpr (is_mulu) {
@ -214,6 +225,7 @@ void multiply(uint16_t source, uint32_t &destination, Status &status, FlowContro
}
}
/// Announce a DIVU or DIVS to @c flow_controller.
template <bool is_divu, bool did_overflow, typename IntT, typename FlowController>
void did_divide(IntT dividend, IntT divisor, FlowController &flow_controller) {
if constexpr (is_divu) {
@ -223,6 +235,7 @@ void did_divide(IntT dividend, IntT divisor, FlowController &flow_controller) {
}
}
/// Perform a DIVU or DIVS between @c source and @c destination, updating @c status and notifying @c flow_controller.
template <bool is_divu, typename Int16, typename Int32, typename FlowController>
void divide(uint16_t source, uint32_t &destination, Status &status, FlowController &flow_controller) {
status.carry_flag = 0;
@ -254,6 +267,7 @@ void divide(uint16_t source, uint32_t &destination, Status &status, FlowControll
did_divide<is_divu, false>(dividend, divisor, flow_controller);
}
/// Move @c source to @c destination, updating @c status.
template <typename IntT> void move(IntT source, IntT &destination, Status &status) {
destination = source;
status.zero_result = Status::FlagT(source);
@ -261,6 +275,7 @@ template <typename IntT> void move(IntT source, IntT &destination, Status &statu
status.overflow_flag = status.carry_flag = 0;
}
/// Perform NEG.[b/l/w] on @c source, updating @c status.
template <bool is_extend, typename IntT> void negative(IntT &source, Status &status) {
const IntT result = -source - (is_extend && status.extend_flag ? 1 : 0);
@ -276,12 +291,14 @@ template <bool is_extend, typename IntT> void negative(IntT &source, Status &sta
source = result;
}
/// Perform TST.[b/l/w] with @c source, updating @c status.
template <typename IntT> void test(IntT source, Status &status) {
status.carry_flag = status.overflow_flag = 0;
status.zero_result = Status::FlagT(source);
status.negative_flag = status.zero_result & top_bit<IntT>();
}
/// Decodes the proper shift distance from @c source, notifying the @c flow_controller.
template <typename IntT, typename FlowController> int shift_count(uint8_t source, FlowController &flow_controller) {
const int count = source & 63;
flow_controller.template did_shift<IntT>(count);
@ -293,6 +310,7 @@ template <typename IntT> constexpr int bit_size() {
return sizeof(IntT) * 8;
}
/// Set the zero and negative flags on @c status according to @c result.
template <typename IntT> void set_neg_zero(IntT result, Status &status) {
status.zero_result = Status::FlagT(result);
status.negative_flag = result & top_bit<IntT>();
@ -985,9 +1003,6 @@ template <
break;
}
#undef u_extend16
#undef s_extend16
}
}