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Factor out free space manipulation

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ISSOtm
2026-09-18 21:19:37 +02:00
committed by Eldred Habert
parent 0e41ace1e3
commit aab22852d3
1 changed files with 64 additions and 59 deletions
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src/link/assign.cpp
+64 -59
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@@ -224,7 +224,65 @@ static FreeSpaceIter tryPlacing(Section const &section, MemoryLocation &location
return freeSpaceOfBank(section, location.bank).end();
}
static std::string getSectionDescription(Section const &section) {
static void
updateFreeSpace(FreeSpaceIter iter, std::deque<FreeSpace> &bankMem, Section const &section) {
assume(section.org + section.size <= UINT16_MAX);
uint16_t sectionEnd = section.org + section.size;
assume(section.org >= iter->address);
assume(sectionEnd <= iter->addrOnePast());
bool noLeftSpace = iter->address == section.org;
bool noRightSpace = iter->address + iter->size == sectionEnd;
if (noLeftSpace && noRightSpace) {
// The free space is entirely deleted
bankMem.erase(iter);
} else if (!noLeftSpace && !noRightSpace) {
// The free space is split in two
uint16_t size = static_cast<uint16_t>(iter->address + iter->size - sectionEnd);
// Resize the original space (address is unmodified)
iter->size = section.org - iter->address;
// Append the new space after the original one
bankMem.insert(iter + 1, {.address = sectionEnd, .size = size});
// `iter` cannot be reused from this point on, because `bankMem.insert`
// invalidates iterators to itself!
} else {
// The amount of free spaces doesn't change: resize!
iter->size -= section.size;
if (noLeftSpace) {
// The free space is moved *and* resized
iter->address += section.size;
}
}
}
// Assigns a section to a given memory location
static void assignSection(Section &section, MemoryLocation const &location) {
assume(location.address >= section.typeInfo().startAddr);
// Zero-sized sections can start one past the end of their region.
assume(location.address <= section.typeInfo().endAddr() + 1);
// This one is not redundant, it guards against overflow!
assume(location.address + section.size >= section.typeInfo().startAddr);
assume(location.address + section.size <= section.typeInfo().endAddr() + 1);
if (section.isAddressFixed) {
assume(location.address == section.org);
} else if (section.isAlignFixed) {
assume((location.address & section.alignMask) == section.alignOfs);
}
if (section.isBankFixed) {
assume(location.bank == section.bank);
}
// Propagate the assigned location to all UNIONs/FRAGMENTs
// so `jr` patches in them will have the correct offset
for (Section &piece : section.pieces()) {
piece.org = location.address;
piece.bank = location.bank;
}
out_AddSection(section);
}
static std::string describeConstraintsOf(Section const &section) {
std::string description = "\"" + section.name + "\" (" + section.typeInfo().name + " section) ";
if (section.isBankFixed && section.typeInfo().isBanked()) {
char bank[9];
@@ -265,33 +323,6 @@ static std::string getSectionDescription(Section const &section) {
return description;
}
// Assigns a section to a given memory location
static void assignSection(Section &section, MemoryLocation const &location) {
assume(location.address >= section.typeInfo().startAddr);
// Zero-sized sections can start one past the end of their region.
assume(location.address <= section.typeInfo().endAddr() + 1);
// This one is not redundant, it guards against overflow!
assume(location.address + section.size >= section.typeInfo().startAddr);
assume(location.address + section.size <= section.typeInfo().endAddr() + 1);
if (section.isAddressFixed) {
assume(location.address == section.org);
} else if (section.isAlignFixed) {
assume((location.address & section.alignMask) == section.alignOfs);
}
if (section.isBankFixed) {
assume(location.bank == section.bank);
}
// Propagate the assigned location to all UNIONs/FRAGMENTs
// so `jr` patches in them will have the correct offset
for (Section &piece : section.pieces()) {
piece.org = location.address;
piece.bank = location.bank;
}
out_AddSection(section);
}
// Places a section in a suitable location, or error out if it fails to.
// Due to the implemented algorithm, this should be called with sections of decreasing size!
static void placeSection(Section &section) {
@@ -305,6 +336,7 @@ static void placeSection(Section &section) {
location.makeAddressAligned(section.alignMask, section.alignOfs);
}
}
assignSection(section, location);
return;
}
@@ -314,46 +346,19 @@ static void placeSection(Section &section) {
iter != bankMem.end()) {
assignSection(section, location);
// Update the free space
assume(section.org + section.size <= UINT16_MAX);
uint16_t sectionEnd = section.org + section.size;
assume(section.org >= iter->address);
assume(sectionEnd <= iter->addrOnePast());
bool noLeftSpace = iter->address == section.org;
bool noRightSpace = iter->address + iter->size == sectionEnd;
if (noLeftSpace && noRightSpace) {
// The free space is entirely deleted
bankMem.erase(iter);
} else if (!noLeftSpace && !noRightSpace) {
// The free space is split in two
uint16_t size = static_cast<uint16_t>(iter->address + iter->size - sectionEnd);
// Resize the original space (address is unmodified)
iter->size = section.org - iter->address;
// Append the new space after the original one
bankMem.insert(iter + 1, {.address = sectionEnd, .size = size});
// **`iter` cannot be reused from this point on, because `bankMem.insert`
// invalidates iterators to itself!**
} else {
// The amount of free spaces doesn't change: resize!
iter->size -= section.size;
if (noLeftSpace) {
// The free space is moved *and* resized
iter->address += section.size;
}
}
updateFreeSpace(iter, bankMem, section);
return;
}
if (!section.isBankFixed || !section.isAddressFixed) {
// If a section failed to go to several places, nothing we can report
fatal("Unable to place %s", getSectionDescription(section).c_str());
fatal("Unable to place %s", describeConstraintsOf(section).c_str());
} else if (uint16_t onePastEnd = section.typeInfo().endAddr() + 1;
section.org + section.size > onePastEnd) {
// If the section just can't fit the bank, report that
fatal(
"Unable to place %s: section runs past end of region ($%04x > $%04x)",
getSectionDescription(section).c_str(),
describeConstraintsOf(section).c_str(),
section.org + section.size,
onePastEnd
);
@@ -363,7 +368,7 @@ static void placeSection(Section &section) {
assume(overlap != nullptr);
fatal(
"Unable to place %s: section overlaps with \"%s\"",
getSectionDescription(section).c_str(),
describeConstraintsOf(section).c_str(),
overlap->name.c_str()
);
}