ref: 3567faf395cdc93d859692eb3c0421b0cdcf702d
dir: /src/link/assign.c/
/*
* This file is part of RGBDS.
*
* Copyright (c) 2019, Eldred Habert and RGBDS contributors.
*
* SPDX-License-Identifier: MIT
*/
#include <inttypes.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "link/assign.h"
#include "link/section.h"
#include "link/symbol.h"
#include "link/object.h"
#include "link/main.h"
#include "link/output.h"
#include "error.h"
#include "helpers.h"
#include "linkdefs.h"
struct MemoryLocation {
uint16_t address;
uint32_t bank;
};
struct FreeSpace {
uint16_t address;
uint16_t size;
struct FreeSpace *next, *prev;
};
// Table of free space for each bank
struct FreeSpace *memory[SECTTYPE_INVALID];
uint64_t nbSectionsToAssign;
// Init the free space-modelling structs
static void initFreeSpace(void)
{
for (enum SectionType type = 0; type < SECTTYPE_INVALID; type++) {
memory[type] = malloc(sizeof(*memory[type]) * nbbanks(type));
if (!memory[type])
err("Failed to init free space for region %d", type);
for (uint32_t bank = 0; bank < nbbanks(type); bank++) {
memory[type][bank].next =
malloc(sizeof(*memory[type][0].next));
if (!memory[type][bank].next)
err("Failed to init free space for region %d bank %" PRIu32,
type, bank);
memory[type][bank].next->address = sectionTypeInfo[type].startAddr;
memory[type][bank].next->size = sectionTypeInfo[type].size;
memory[type][bank].next->next = NULL;
memory[type][bank].next->prev = &memory[type][bank];
}
}
}
/*
* Assigns a section to a given memory location
* @param section The section to assign
* @param location The location to assign the section to
*/
static void assignSection(struct Section *section, struct MemoryLocation const *location)
{
section->org = location->address;
section->bank = location->bank;
// Propagate the assigned location to all UNIONs/FRAGMENTs
// so `jr` patches in them will have the correct offset
for (struct Section *next = section->nextu; next != NULL; next = next->nextu) {
next->org = section->org;
next->bank = section->bank;
}
nbSectionsToAssign--;
out_AddSection(section);
}
/*
* 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.
* @param section The section to be placed
* @param freeSpace The candidate free space to place the section into
* @param location The location to attempt placing the section at
* @return True if the location is suitable, false otherwise.
*/
static bool isLocationSuitable(struct Section const *section,
struct FreeSpace const *freeSpace,
struct MemoryLocation const *location)
{
if (section->isAddressFixed && section->org != location->address)
return false;
if (section->isAlignFixed
&& ((location->address - section->alignOfs) & section->alignMask))
return false;
if (location->address < freeSpace->address)
return false;
return location->address + section->size
<= freeSpace->address + freeSpace->size;
}
/*
* Finds a suitable location to place a section at.
* @param section The section to be placed
* @param location A pointer to a location struct that will be filled
* @return A pointer to the free space encompassing the location, or NULL if
* none was found
*/
static struct FreeSpace *getPlacement(struct Section const *section,
struct MemoryLocation *location)
{
static uint16_t curScrambleROM = 1;
static uint8_t curScrambleWRAM = 1;
static uint8_t curScrambleSRAM = 1;
// Determine which bank we should start searching in
if (section->isBankFixed) {
location->bank = section->bank;
} else if (scrambleROMX && section->type == SECTTYPE_ROMX) {
location->bank = curScrambleROM++;
if (curScrambleROM > scrambleROMX)
curScrambleROM = 1;
} else if (scrambleWRAMX && section->type == SECTTYPE_WRAMX) {
location->bank = curScrambleWRAM++;
if (curScrambleWRAM > scrambleWRAMX)
curScrambleWRAM = 1;
} else if (scrambleSRAM && section->type == SECTTYPE_SRAM) {
location->bank = curScrambleSRAM++;
if (curScrambleSRAM > scrambleSRAM)
curScrambleSRAM = 0;
} else {
location->bank = sectionTypeInfo[section->type].firstBank;
}
struct FreeSpace *space;
for (;;) {
// Switch to the beginning of the next bank
#define BANK_INDEX (location->bank - sectionTypeInfo[section->type].firstBank)
space = memory[section->type][BANK_INDEX].next;
if (space)
location->address = space->address;
// Process locations in that bank
while (space) {
// If that location is OK, return it
if (isLocationSuitable(section, space, location))
return space;
// Go to the next *possible* location
if (section->isAddressFixed) {
// If the address is fixed, there can be only
// one candidate block per bank; if we already
// reached it, give up.
if (location->address < section->org)
location->address = section->org;
else
// Try again in next bank
space = NULL;
} else if (section->isAlignFixed) {
// Move to next aligned location
// Move back to alignment boundary
location->address -= section->alignOfs;
// Ensure we're there (e.g. on first check)
location->address &= ~section->alignMask;
// Go to next align boundary and add offset
location->address += section->alignMask + 1
+ section->alignOfs;
} else {
// Any location is fine, so, next free block
space = space->next;
if (space)
location->address = space->address;
}
// If that location is past the current block's end,
// go forwards until that is no longer the case.
while (space && location->address >=
space->address + space->size)
space = space->next;
// Try again with the new location/free space combo
}
if (section->isBankFixed)
return NULL;
// Try again in the next bank
location->bank++;
if (location->bank > sectionTypeInfo[section->type].lastBank)
return NULL;
#undef BANK_INDEX
}
}
/*
* Places a section in a suitable location, or error out if it fails to.
* @warning Due to the implemented algorithm, this should be called with
* sections of decreasing size.
* @param section The section to place
*/
static void placeSection(struct Section *section)
{
struct MemoryLocation location;
// Specially handle 0-byte SECTIONs, as they can't overlap anything
if (section->size == 0) {
// Unless the SECTION's address was fixed, the starting address
// is fine for any alignment, as checked in sect_DoSanityChecks.
location.address = section->isAddressFixed
? section->org
: sectionTypeInfo[section->type].startAddr;
location.bank = section->isBankFixed
? section->bank
: sectionTypeInfo[section->type].firstBank;
assignSection(section, &location);
return;
}
// Place section using first-fit decreasing algorithm
// https://en.wikipedia.org/wiki/Bin_packing_problem#First-fit_algorithm
struct FreeSpace *freeSpace = getPlacement(section, &location);
if (freeSpace) {
assignSection(section, &location);
// Split the free space
bool noLeftSpace = freeSpace->address == section->org;
bool noRightSpace = freeSpace->address + freeSpace->size
== section->org + section->size;
if (noLeftSpace && noRightSpace) {
// The free space is entirely deleted
freeSpace->prev->next = freeSpace->next;
if (freeSpace->next)
freeSpace->next->prev = freeSpace->prev;
// If the space is the last one on the list, set its
// size to 0 so it doesn't get picked, but don't free()
// it as it will be freed when cleaning up
free(freeSpace);
} else if (!noLeftSpace && !noRightSpace) {
// The free space is split in two
struct FreeSpace *newSpace = malloc(sizeof(*newSpace));
if (!newSpace)
err("Failed to split new free space");
// Append the new space after the chosen one
newSpace->prev = freeSpace;
newSpace->next = freeSpace->next;
if (freeSpace->next)
freeSpace->next->prev = newSpace;
freeSpace->next = newSpace;
// Set its parameters
newSpace->address = section->org + section->size;
newSpace->size = freeSpace->address + freeSpace->size -
newSpace->address;
// Set the original space's new parameters
freeSpace->size = section->org - freeSpace->address;
// address is unmodified
} else {
// The amount of free spaces doesn't change: resize!
freeSpace->size -= section->size;
if (noLeftSpace)
// The free space is moved *and* resized
freeSpace->address += section->size;
}
return;
}
// Please adjust depending on longest message below
char where[64];
if (section->isBankFixed && nbbanks(section->type) != 1) {
if (section->isAddressFixed)
snprintf(where, 64, "at $%02" PRIx32 ":%04" PRIx16,
section->bank, section->org);
else if (section->isAlignFixed)
snprintf(where, 64, "in bank $%02" PRIx32 " with align mask %" PRIx16,
section->bank, (uint16_t)~section->alignMask);
else
snprintf(where, 64, "in bank $%02" PRIx32,
section->bank);
} else {
if (section->isAddressFixed)
snprintf(where, 64, "at address $%04" PRIx16,
section->org);
else if (section->isAlignFixed)
snprintf(where, 64, "with align mask %" PRIx16 " and offset %" PRIx16,
(uint16_t)~section->alignMask,
section->alignOfs);
else
strcpy(where, "anywhere");
}
// If a section failed to go to several places, nothing we can report
if (!section->isBankFixed || !section->isAddressFixed)
errx("Unable to place \"%s\" (%s section) %s",
section->name, sectionTypeInfo[section->type].name, where);
// If the section just can't fit the bank, report that
else if (section->org + section->size > endaddr(section->type) + 1)
errx("Unable to place \"%s\" (%s section) %s: section runs past end of region ($%04x > $%04x)",
section->name, sectionTypeInfo[section->type].name, where,
section->org + section->size, endaddr(section->type) + 1);
// Otherwise there is overlap with another section
else
errx("Unable to place \"%s\" (%s section) %s: section overlaps with \"%s\"",
section->name, sectionTypeInfo[section->type].name, where,
out_OverlappingSection(section)->name);
}
struct UnassignedSection {
struct Section *section;
struct UnassignedSection *next;
};
#define BANK_CONSTRAINED (1 << 2)
#define ORG_CONSTRAINED (1 << 1)
#define ALIGN_CONSTRAINED (1 << 0)
static struct UnassignedSection *unassignedSections[1 << 3] = {0};
static struct UnassignedSection *sections;
/*
* Categorize a section depending on how constrained it is
* This is so the most-constrained sections are placed first
* @param section The section to categorize
* @param arg Callback arg, unused
*/
static void categorizeSection(struct Section *section, void *arg)
{
(void)arg;
uint8_t constraints = 0;
if (section->isBankFixed)
constraints |= BANK_CONSTRAINED;
if (section->isAddressFixed)
constraints |= ORG_CONSTRAINED;
// Can't have both!
else if (section->isAlignFixed)
constraints |= ALIGN_CONSTRAINED;
struct UnassignedSection **ptr = &unassignedSections[constraints];
// Insert section while keeping the list sorted by decreasing size
while (*ptr && (*ptr)->section->size > section->size)
ptr = &(*ptr)->next;
sections[nbSectionsToAssign].section = section;
sections[nbSectionsToAssign].next = *ptr;
*ptr = §ions[nbSectionsToAssign];
nbSectionsToAssign++;
}
void assign_AssignSections(void)
{
verbosePrint("Beginning assignment...\n");
// Initialize assignment
// Generate linked lists of sections to assign
sections = malloc(sizeof(*sections) * nbSectionsToAssign + 1);
if (!sections)
err("Failed to allocate memory for section assignment");
initFreeSpace();
nbSectionsToAssign = 0;
sect_ForEach(categorizeSection, NULL);
// Place sections, starting with the most constrained
// Specially process fully-constrained sections because of overlaying
struct UnassignedSection *sectionPtr =
unassignedSections[BANK_CONSTRAINED | ORG_CONSTRAINED];
verbosePrint("Assigning bank+org-constrained...\n");
while (sectionPtr) {
placeSection(sectionPtr->section);
sectionPtr = sectionPtr->next;
}
// If all sections were fully constrained, we have nothing left to do
if (!nbSectionsToAssign)
return;
// Overlaying requires only fully-constrained sections
verbosePrint("Assigning other sections...\n");
if (overlayFileName) {
fprintf(stderr, "FATAL: All sections must be fixed when using an overlay file");
uint8_t nbSections = 0;
for (int8_t constraints = BANK_CONSTRAINED | ALIGN_CONSTRAINED; constraints >= 0; constraints--) {
for (sectionPtr = unassignedSections[constraints];
sectionPtr;
sectionPtr = sectionPtr->next) {
fprintf(stderr, "%c \"%s\"",
nbSections == 0 ? ';': ',', sectionPtr->section->name);
nbSections++;
if (nbSections == 10)
goto max_out;
}
}
max_out:
if (nbSectionsToAssign != nbSections)
fprintf(stderr, " and %" PRIu64 " more", nbSectionsToAssign - nbSections);
fprintf(stderr, " %sn't\n", nbSectionsToAssign == 1 ? "is" : "are");
exit(1);
}
// Assign all remaining sections by decreasing constraint order
for (int8_t constraints = BANK_CONSTRAINED | ALIGN_CONSTRAINED;
constraints >= 0; constraints--) {
sectionPtr = unassignedSections[constraints];
while (sectionPtr) {
placeSection(sectionPtr->section);
sectionPtr = sectionPtr->next;
}
if (!nbSectionsToAssign)
return;
}
unreachable_();
}
void assign_Cleanup(void)
{
for (enum SectionType type = 0; type < SECTTYPE_INVALID; type++) {
for (uint32_t bank = 0; bank < nbbanks(type); bank++) {
struct FreeSpace *ptr =
memory[type][bank].next;
while (ptr) {
struct FreeSpace *next = ptr->next;
free(ptr);
ptr = next;
}
}
free(memory[type]);
}
free(sections);
}