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Trust the compiler with this bit field.

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This commit is contained in:
Thomas Harte 2021-12-23 16:28:55 -05:00
parent d9598b35c2
commit 32e0a66610
2 changed files with 27 additions and 14 deletions
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6
Processors/68000/Implementation/68000Implementation.hpp
View File

@ -333,7 +333,7 @@ template <class T, bool dtack_is_implicit, bool signal_will_perform> void Proces
#endif
if(instructions[decoded_instruction_.full].micro_operations != std::numeric_limits<uint32_t>::max()) {
if((instructions[decoded_instruction_.full].source_dest & 0x80) && !is_supervisor_) {
if((instructions[decoded_instruction_.full].requires_supervisor) && !is_supervisor_) {
// A privilege violation has been detected.
active_program_ = nullptr;
active_micro_op_ = short_exception_micro_ops_;
@ -387,9 +387,9 @@ template <class T, bool dtack_is_implicit, bool signal_will_perform> void Proces
#define offset_pointer(x) reinterpret_cast<RegisterPair32 *>(&reinterpret_cast<uint8_t *>(static_cast<ProcessorStorage *>(this))[x])
#define source() offset_pointer(active_program_->source_offset)
#define source_address() address_[(active_program_->source_dest >> 4) & 7]
#define source_address() address_[active_program_->source]
#define destination() offset_pointer(active_program_->destination_offset)
#define destination_address() address_[active_program_->source_dest & 7]
#define destination_address() address_[active_program_->dest]
case int_type(MicroOp::Action::PerformOperation):
#define sub_overflow() ((result ^ destination) & (destination ^ source))

35
Processors/68000/Implementation/68000Storage.hpp
View File

@ -359,6 +359,15 @@ class ProcessorStorage {
remaining fields, with no additional padding being inserted by the compiler.
*/
struct Program {
Program() {
// Initialisers for bitfields aren't available until C++20. So, yuck, do it manually.
requires_supervisor = 0;
source = 0;
dest = 0;
destination_offset = 0;
source_offset = 0;
}
/// The offset into the all_micro_ops_ at which micro-ops for this instruction begin,
/// or std::numeric_limits<uint32_t>::max() if this is an invalid Program.
uint32_t micro_operations = std::numeric_limits<uint32_t>::max();
@ -366,26 +375,30 @@ class ProcessorStorage {
Operation operation;
/// The number of bytes after the beginning of an instance of ProcessorStorage that the RegisterPair32 containing
/// a source value for this operation lies at.
uint8_t source_offset = 0;
uint8_t source_offset: 7;
/// The number of bytes after the beginning of an instance of ProcessorStorage that the RegisterPair32 containing
/// a destination value for this operation lies at.
uint8_t destination_offset = 0;
/// A bitfield comprised of:
/// b7 = set if this program requires supervisor mode;
/// b0–b2 = the source address register (for pre-decrement and post-increment actions); and
/// b4-b6 = destination address register.
uint8_t source_dest = 0;
uint8_t destination_offset: 7;
/// Set if this program requires supervisor mode.
bool requires_supervisor: 1;
/// The source address register (for pre-decrement and post-increment actions).
uint8_t source: 3;
/// Destination address register.
uint8_t dest: 3;
void set_source_address([[maybe_unused]] ProcessorStorage &storage, int index) {
source_dest = uint8_t((source_dest & 0x0f) | (index << 4));
source = uint8_t(index);
assert(int(source) == index);
}
void set_destination_address([[maybe_unused]] ProcessorStorage &storage, int index) {
source_dest = uint8_t((source_dest & 0xf0) | index);
dest = uint8_t(index);
assert(int(dest) == index);
}
void set_requires_supervisor(bool requires_supervisor) {
source_dest = (source_dest & 0x7f) | (requires_supervisor ? 0x80 : 0x00);
void set_requires_supervisor(bool req) {
requires_supervisor = req;
assert(requires_supervisor == req);
}
void set_source(ProcessorStorage &storage, RegisterPair32 *target) {