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Refactor registers a bit to make unit tests work again

pull/289/head
D.R.racer 2023-08-05 02:03:00 +02:00 committed by DRracer
parent 93a344bde8
commit 77a8788821
2 changed files with 42 additions and 43 deletions
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13
src/hal/progmem.h
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@ -31,5 +31,18 @@ static inline uint8_t read_byte(const uint8_t *addr) {
#endif
}
/// read a ptr from PROGMEM
/// Introduced mainly for compatibility reasons with the unit tests
/// and to hide the ugly reinterpret_casts.
/// Returns a correctly typed pointer: a 16-bit on AVR, but a 64bit address on x86_64
template <typename RT>
static inline RT read_ptr(const void *addr) {
#ifndef __AVR__
return reinterpret_cast<RT>(*reinterpret_cast<const uint64_t *>(addr));
#else
return reinterpret_cast<RT>(pgm_read_ptr(addr));
#endif
}
} // namespace progmem
} // namespace hal

68
src/registers.cpp
View File

@ -167,8 +167,8 @@
| 0x21h 33 | uint16 | Reserved for internal use | 225 | | N/A | N/A | N/A | N/A
*/
struct RegisterFlags {
struct A {
struct __attribute__((packed)) RegisterFlags {
struct __attribute__((packed)) A {
uint8_t size : 2; // 0: 1 bit, 1: 1 byte, 2: 2 bytes - keeping size as the lowest 2 bits avoids costly shifts when accessing them
uint8_t writable : 1;
uint8_t rwfuncs : 1; // 1: register needs special read and write functions
@ -181,7 +181,7 @@ struct RegisterFlags {
, writable(writable)
, rwfuncs(rwfuncs) {}
};
union U {
union __attribute__((packed)) U {
A bits;
uint8_t b;
constexpr U(uint8_t size, bool writable)
@ -195,7 +195,7 @@ struct RegisterFlags {
: u(size, writable) {}
constexpr RegisterFlags(uint8_t size, bool writable, bool rwfuncs)
: u(size, writable, rwfuncs) {}
constexpr RegisterFlags(uint8_t b)
explicit constexpr RegisterFlags(uint8_t b)
: u(b) {}
constexpr bool Writable() const { return u.bits.writable; }
@ -203,15 +203,17 @@ struct RegisterFlags {
constexpr uint8_t Size() const { return u.bits.size; }
};
static_assert(sizeof(RegisterFlags) == 1);
using TReadFunc = uint16_t (*)();
using TWriteFunc = void (*)(uint16_t);
// dummy zero register common to all empty registers
static constexpr uint16_t dummyZero = 0;
struct RegisterRec {
struct __attribute__((packed)) RegisterRec {
RegisterFlags flags;
union U1 {
union __attribute__((packed)) U1 {
void *addr;
TReadFunc readFunc;
constexpr explicit U1(const TReadFunc &r)
@ -220,7 +222,7 @@ struct RegisterRec {
: addr(a) {}
} A1;
union U2 {
union __attribute__((packed)) U2 {
void *addr;
TWriteFunc writeFunc;
constexpr explicit U2(const TWriteFunc &w)
@ -250,6 +252,12 @@ struct RegisterRec {
, A2((void *)nullptr) {}
};
// Make sure the structure is tightly packed - necessary for unit tests.
static_assert(sizeof(RegisterRec) == sizeof(uint8_t) + sizeof(void *) + sizeof(void *));
// Beware: the size is expected to be 17B on an x86_64 and it requires the platform to be able to do unaligned reads.
// That might be a problem when running unit tests on non-x86 platforms.
// So far, no countermeasures have been taken to tackle this potential issue.
// @@TODO it is nice to see all the supported registers at one spot,
// however it requires including all bunch of dependencies
// which makes unit testing and separation of modules much harder.
@ -434,39 +442,26 @@ bool ReadRegister(uint8_t address, uint16_t &value) {
value = 0;
// Get pointer to register at address
#ifndef UNITTEST
// beware - abusing the knowledge of RegisterRec memory layout to do lpm_reads
const uint8_t *addr = reinterpret_cast<const uint8_t *>(registers + address);
const RegisterFlags rf(hal::progmem::read_byte(addr));
#else
const RegisterRec *reg = registers + address;
const RegisterFlags rf = reg->flags;
#endif
// beware - abusing the knowledge of RegisterRec memory layout to do lpm_reads
const void *varAddr = addr + sizeof(RegisterFlags);
if (!rf.RWFuncs()) {
const uint16_t *varAddr = reinterpret_cast<const uint16_t *>(addr + 1);
switch (rf.Size()) {
case 0:
case 1:
value = *reinterpret_cast<const uint8_t *>(hal::progmem::read_word(varAddr));
value = *hal::progmem::read_ptr<const uint8_t *>(varAddr);
break;
case 2:
value = *reinterpret_cast<const uint16_t *>(hal::progmem::read_word(varAddr));
value = *hal::progmem::read_ptr<const uint16_t *>(varAddr);
break;
default:
return false;
}
return true;
} else {
switch (rf.Size()) {
case 0:
case 1:
case 2: {
const TReadFunc readFunc = reinterpret_cast<const TReadFunc>(pgm_read_word(addr + 1));
auto readFunc = hal::progmem::read_ptr<const TReadFunc>(varAddr);
value = readFunc();
} break;
default:
return false;
}
return true;
}
}
@ -476,40 +471,31 @@ bool WriteRegister(uint8_t address, uint16_t value) {
return false;
}
#ifndef UNITTEST
const uint8_t *addr = reinterpret_cast<const uint8_t *>(registers + address);
const RegisterFlags rf(hal::progmem::read_byte(addr));
#else
RegisterRec reg = registers[address];
#endif
if (!rf.Writable()) {
return false;
}
// beware - abusing the knowledge of RegisterRec memory layout to do lpm_reads
// addr offset should be 3 on AVR, but 9 on x86_64, therefore "1 + sizeof(void*)"
const void *varAddr = addr + sizeof(RegisterFlags) + sizeof(RegisterRec::A1);
if (!rf.RWFuncs()) {
const uint16_t *varAddr = reinterpret_cast<const uint16_t *>(addr + 3);
switch (rf.Size()) {
case 0:
case 1:
*reinterpret_cast<uint8_t *>(hal::progmem::read_word(varAddr)) = value;
*hal::progmem::read_ptr<uint8_t *>(varAddr) = value;
break;
case 2:
*reinterpret_cast<uint16_t *>(hal::progmem::read_word(varAddr)) = value;
*hal::progmem::read_ptr<uint16_t *>(varAddr) = value;
break;
default:
return false;
}
return true;
} else {
switch (rf.Size()) {
case 0:
case 1:
case 2: {
const TWriteFunc writeFunc = reinterpret_cast<const TWriteFunc>(pgm_read_word(addr + 3));
auto writeFunc = hal::progmem::read_ptr<const TWriteFunc>(varAddr);
writeFunc(value);
} break;
default:
return false;
}
return true;
}
}