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Refactor all scrambling-related dispatch into a single func

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Yay for (poor man's) pattern matching! 🦀
This commit is contained in:
ISSOtm
2026-09-18 21:19:37 +02:00
committed by Eldred Habert
parent 1ca4282e31
commit 8685bcbfbf
1 changed files with 56 additions and 44 deletions
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src/link/assign.cpp
+56 -44
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@@ -36,6 +36,50 @@ struct FreeSpace {
// Table of free space for each bank
static std::vector<std::deque<FreeSpace>> memory[SECTTYPE_INVALID];
struct Scrambling {
uint16_t romxOfs = 0;
uint16_t sramOfs = 0;
uint16_t wramxOfs = 0;
// Helper for the next function, to give names to its two returned values.
struct ScramblingInfo {
uint16_t &curOfs;
uint16_t maxOfs;
};
std::optional<ScramblingInfo> getInfoFor(SectionType type) {
switch (type) {
case SECTTYPE_ROMX:
return {
{romxOfs, options.scrambleROMX}
};
case SECTTYPE_SRAM:
return {
{sramOfs, options.scrambleSRAM}
};
case SECTTYPE_WRAMX:
return {
{wramxOfs, options.scrambleWRAMX}
};
// Non-banked sections don't need scrambling support...
case SECTTYPE_ROM0:
case SECTTYPE_WRAM0:
case SECTTYPE_OAM:
case SECTTYPE_HRAM:
assume(!sectionTypeInfo[type].isBanked());
return std::nullopt;
// ...but VRAM doesn't either, regardless of whether it's banked or not.
case SECTTYPE_VRAM:
return std::nullopt;
case SECTTYPE_INVALID:
unreachable_();
}
return std::nullopt; // Dead code, but some compilers don't recognize that.
}
};
static Scrambling scrambling;
// Checks whether a given location is suitable for placing a given section
// This checks not only that the location has enough room for the section, but
// also that the constraints (alignment...) are respected.
@@ -58,10 +102,6 @@ static bool isLocationSuitable(
}
static MemoryLocation getStartLocation(Section const &section) {
static uint16_t curScrambleROM = 0;
static uint16_t curScrambleWRAM = 0;
static uint16_t curScrambleSRAM = 0;
MemoryLocation location;
// Determine which bank we should start searching in
@@ -70,22 +110,10 @@ static MemoryLocation getStartLocation(Section const &section) {
} else {
location.bank = section.typeInfo().firstBank;
// Scramble the bank if applicable
if (options.scrambleROMX && section.type == SECTTYPE_ROMX) {
if (curScrambleROM == 0) {
curScrambleROM = options.scrambleROMX;
}
location.bank += --curScrambleROM;
} else if (options.scrambleWRAMX && section.type == SECTTYPE_WRAMX) {
if (curScrambleWRAM == 0) {
curScrambleWRAM = options.scrambleWRAMX;
}
location.bank += --curScrambleWRAM;
} else if (options.scrambleSRAM && section.type == SECTTYPE_SRAM) {
if (curScrambleSRAM == 0) {
curScrambleSRAM = options.scrambleSRAM;
}
location.bank += --curScrambleSRAM;
if (auto info = scrambling.getInfoFor(section.type);
info.has_value() && info->maxOfs != 0) {
info->curOfs = (info->curOfs != 0 ? info->curOfs : info->maxOfs) - 1;
location.bank += info->curOfs;
}
}
@@ -168,30 +196,13 @@ static std::optional<size_t> getPlacement(Section const &section, MemoryLocation
// available. Otherwise, try in ascending order.
if (section.isBankFixed) {
return std::nullopt;
} else if (options.scrambleROMX && section.type == SECTTYPE_ROMX
&& location.bank <= options.scrambleROMX) {
} else if (
auto info = scrambling.getInfoFor(section.type); info.has_value() && info->maxOfs != 0
) {
if (location.bank > typeInfo.firstBank) {
--location.bank;
} else if (options.scrambleROMX < typeInfo.lastBank) {
location.bank = options.scrambleROMX + 1;
} else {
return std::nullopt;
}
} else if (options.scrambleWRAMX && section.type == SECTTYPE_WRAMX
&& location.bank <= options.scrambleWRAMX) {
if (location.bank > typeInfo.firstBank) {
--location.bank;
} else if (options.scrambleWRAMX < typeInfo.lastBank) {
location.bank = options.scrambleWRAMX + 1;
} else {
return std::nullopt;
}
} else if (options.scrambleSRAM && section.type == SECTTYPE_SRAM
&& location.bank <= options.scrambleSRAM) {
if (location.bank > typeInfo.firstBank) {
--location.bank;
} else if (options.scrambleSRAM < typeInfo.lastBank) {
location.bank = options.scrambleSRAM + 1;
} else if (info->maxOfs < typeInfo.lastBank) {
location.bank = info->maxOfs + 1;
} else {
return std::nullopt;
}
@@ -313,8 +324,9 @@ static void placeSection(Section &section) {
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());
} else if (uint16_t onePastEnd = typeInfo.endAddr() + 1;
section.org + section.size > onePastEnd) {
} else if (
uint16_t onePastEnd = 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)",