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04dfcd707b448155fa38050c3571552c35f5ce09
SplitBit-Emulator/Source/Assembler/secondPass.c
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// secondPass.c
// Functions for the 'second pass' of the SplitBit Assembler.
// The goal here is to resolve the addresses of labels.
// We'll want to abort if the program comes out to greater than the maximum memory for SplitBit.
// We'll also want to abort if there's a label used with no definition.
// Written by Anachronaut
// 10/25/2024
#include <stdlib.h>
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <stdint.h>
#include "secondPass.h"
#include "Assm-util.h"
#include "assembly.h"
int debugSecondPass = 0;
Label labelArray[MAX_LABELS];
int labelCount = 0;
void freeLabelList() {
for (int i = 0; i < labelCount; i++) {
if (labelArray[i].label) {
free(labelArray[i].label);
}
}
labelCount = 0;
}
void addLabel(char *labelName, uint16_t address, int type, const char *fileName, int lineNumber) {
if (labelCount < MAX_LABELS) {
// Duplicate labelName and remove the trailing colon, if present
char *cleanedLabel = strdup(labelName);
int len = strlen(cleanedLabel);
if (cleanedLabel[len - 1] == ':') {
cleanedLabel[len - 1] = '\0'; // Remove the colon
}
// A name may only be defined once. Without this check a reference quietly
// resolves to whichever definition came first, so a typo or a name that two
// libraries both happen to use is very hard to track down.
for (int i = 0; i < labelCount; i++) {
if (strcmp(labelArray[i].label, cleanedLabel) == 0) {
fprintf(stderr, RED "Error: Label \"%s\" is defined more than once.\n" RESET, cleanedLabel);
printf("File: %s at line %d.\n", fileName, lineNumber);
free(cleanedLabel);
exit(1);
}
}
labelArray[labelCount].label = cleanedLabel;
labelArray[labelCount].address = address;
labelArray[labelCount].type = type;
if (debugSecondPass) printf("Added label %s with address %04X\n", labelName, labelArray[labelCount].address);
labelCount++;
} else {
fprintf(stderr, "Error: Too many labels defined.\n");
exit(1);
}
}
void populateLabelTable(intermediateElement *intermediateArray, int arraySize) {
int programCount = 0;
int dataCount = 0;
// Loop through the array, if there's a label definition, add it to the label list.
for (int i = 0; i < arraySize ; i++) {
// How many zeroes an #Align comes to depends on where the cursor has reached,
// so it can only be worked out here, walking the tokens in order. It has to be
// settled before the running count moves past it, or every label after it lands
// in the wrong place.
if (intermediateArray[i].type == ALIGNMENT) {
int cursor = (intermediateArray[i].destination == PROGRAM) ? programCount : dataCount;
int alignment = intermediateArray[i].address;
intermediateArray[i].byteLength = (alignment - (cursor % alignment)) % alignment;
}
if (intermediateArray[i].type == LABEL_DEFINITION && intermediateArray[i].destination != VECTORS) {
if (intermediateArray[i].destination == PROGRAM) {
addLabel(intermediateArray[i].token, (uint16_t)programCount, PROGRAM,
intermediateArray[i].fileName, intermediateArray[i].lineNumber);
} else {
addLabel(intermediateArray[i].token, (uint16_t)dataCount, DATA,
intermediateArray[i].fileName, intermediateArray[i].lineNumber);
}
}
if (intermediateArray[i].destination == PROGRAM) {
programCount += intermediateArray[i].byteLength;
} else if (intermediateArray[i].destination == DATA) {
dataCount += intermediateArray[i].byteLength;
}
if (debugSecondPass) printf("Token: %s with byte length %d to destination %d of type %d\n", intermediateArray[i].token ,intermediateArray[i].byteLength, intermediateArray[i].destination, intermediateArray[i].type);
}
if (programCount > PROGRAM_TEXT_LIMIT ) {
fprintf(stderr, RED "Error: Program is too long to fit in Program Memory.\n"
" Program text may not run past 0x%04X, where the vector table begins.\n" RESET,
PROGRAM_TEXT_LIMIT - 1);
exit(1);
}
if (dataCount > 0xFFFF ) {
fprintf(stderr, RED "Error: Data is too long to fit in Data Memory.\n" RESET);
exit(1);
}
}
// ---- The Vector Segment ----
int findLabelAddress(const char *labelName);
VectorEntry vectorArray[MAX_VECTORS];
int vectorArrayCount = 0;
int vectorCount() {
return vectorArrayCount;
}
void freeVectorList() {
for (int i = 0; i < vectorArrayCount; i++) {
if (vectorArray[i].name) {
free(vectorArray[i].name);
}
}
vectorArrayCount = 0;
}
// The words the Vector Segment understands. These are spelled without regard to case,
// the way mnemonics are, because they are part of the language rather than names the
// programmer chose.
static int sameWord(const char *a, const char *b) {
while (*a && *b) {
if (tolower((unsigned char)*a) != tolower((unsigned char)*b)) {
return 0;
}
a++;
b++;
}
return *a == *b;
}
// The vectors that already mean something. Everything else a program names is numbered
// for it, starting above the range held back for faults.
static const struct {
const char *name;
uint8_t index;
} reservedVectors[] = {
{ "Boot", VECTOR_BOOT },
{ "SoftReset", VECTOR_SOFT_RESET },
{ "BadOpcode", VECTOR_INVALID_OPCODE },
{ "GuardViolation", VECTOR_GUARD_VIOLATION },
{ "BankFault", VECTOR_BANK_FAULT },
};
static const int reservedVectorCount = (int)(sizeof(reservedVectors) / sizeof(reservedVectors[0]));
static void vectorError(const char *message, intermediateElement *element) {
fprintf(stderr, RED "Error: %s\n" RESET, message);
printf("File: %s at line %d.\n", element->fileName, element->lineNumber);
printf("Token: %s\n", element->token);
exit(1);
}
// The next token belonging to the Vector Segment, or -1 if the segment has run out.
static int nextVectorToken(intermediateElement *intermediateArray, int arraySize, int from) {
for (int i = from; i < arraySize; i++) {
if (intermediateArray[i].destination == VECTORS && intermediateArray[i].type != KEYWORD) {
return i;
}
}
return -1;
}
static void addVector(char *name, uint8_t index, uint16_t base, uint16_t handler, intermediateElement *element) {
if (vectorArrayCount >= MAX_VECTORS) {
vectorError("Too many vectors defined.", element);
}
for (int i = 0; i < vectorArrayCount; i++) {
if (vectorArray[i].index == index && vectorArray[i].base == base) {
fprintf(stderr, RED "Error: That vector already has a handler.\n" RESET);
printf("File: %s at line %d.\n", element->fileName, element->lineNumber);
exit(1);
}
if (name && vectorArray[i].name && strcmp(vectorArray[i].name, name) == 0) {
fprintf(stderr, RED "Error: Vector \"%s\" is named more than once.\n" RESET, name);
printf("File: %s at line %d.\n", element->fileName, element->lineNumber);
exit(1);
}
}
vectorArray[vectorArrayCount].name = name ? strdup(name) : NULL;
vectorArray[vectorArrayCount].index = index;
vectorArray[vectorArrayCount].base = base;
vectorArray[vectorArrayCount].handler = handler;
vectorArrayCount++;
}
// Resolves the handler named by the token at the given index.
static uint16_t resolveHandler(intermediateElement *intermediateArray, int at, const char *what) {
if (at < 0) {
fprintf(stderr, RED "Error: %s is not followed by a handler to go to.\n" RESET, what);
exit(1);
}
if (intermediateArray[at].type != LABEL) {
vectorError("A vector's handler has to be named by a label.", &intermediateArray[at]);
}
int address = findLabelAddress(intermediateArray[at].token);
if (address == -1) {
vectorError("That handler does not exist.", &intermediateArray[at]);
}
return (uint16_t)address;
}
void populateVectorTable(intermediateElement *intermediateArray, int arraySize) {
// Software vectors a program names for itself are numbered in the order they are
// written, starting above the block held back for faults. A programmer never types
// one, so there is no way to land on a reserved vector by accident.
int nextFreeVector = VECTOR_FIRST_FREE;
int i = nextVectorToken(intermediateArray, arraySize, 0);
while (i >= 0) {
char *token = intermediateArray[i].token;
if (sameWord(token, "Device")) {
// A device is named by the port it is plugged into, because that is what
// decides which vector it arrives through. There is nothing to allocate.
int portToken = nextVectorToken(intermediateArray, arraySize, i + 1);
if (portToken < 0 || intermediateArray[portToken].type != VALUE) {
vectorError("Device has to say which port, as a number.", &intermediateArray[i]);
}
int handlerToken = nextVectorToken(intermediateArray, arraySize, portToken + 1);
uint16_t handler = resolveHandler(intermediateArray, handlerToken, "Device");
addVector(NULL, intermediateArray[portToken].byteValue, HARDWARE_VECTOR_BASE,
handler, &intermediateArray[i]);
i = nextVectorToken(intermediateArray, arraySize, handlerToken + 1);
continue;
}
uint8_t index;
int reserved = 0;
for (int r = 0; r < reservedVectorCount; r++) {
if (sameWord(token, reservedVectors[r].name)) {
index = reservedVectors[r].index;
reserved = 1;
break;
}
}
if (!reserved) {
if (nextFreeVector > 255) {
vectorError("There are no software vectors left to give this one.", &intermediateArray[i]);
}
index = (uint8_t)nextFreeVector;
nextFreeVector++;
}
int handlerToken = nextVectorToken(intermediateArray, arraySize, i + 1);
uint16_t handler = resolveHandler(intermediateArray, handlerToken, token);
addVector(token, index, SOFTWARE_VECTOR_BASE, handler, &intermediateArray[i]);
i = nextVectorToken(intermediateArray, arraySize, handlerToken + 1);
}
}
void fillInVectorReferences(intermediateElement *intermediateArray, int arraySize) {
for (int i = 0; i < arraySize; i++) {
if (intermediateArray[i].type != VECTOR_REFERENCE) {
continue;
}
int found = 0;
for (int v = 0; v < vectorArrayCount; v++) {
if (vectorArray[v].name && strcmp(vectorArray[v].name, intermediateArray[i].token) == 0) {
if (vectorArray[v].base != SOFTWARE_VECTOR_BASE) {
vectorError("SWI can only reach a software vector.", &intermediateArray[i]);
}
intermediateArray[i].byteValue = vectorArray[v].index;
found = 1;
break;
}
}
if (!found) {
fprintf(stderr, RED "Error: \"%s\" is not a vector.\n Names used with SWI have to be given a handler in a #Vectors section.\n" RESET,
intermediateArray[i].token);
printf("File: %s at line %d.\n", intermediateArray[i].fileName, intermediateArray[i].lineNumber);
exit(1);
}
}
}
int findLabelAddress(const char *labelName) {
for (int i = 0; i < labelCount; i++) {
if (strcmp(labelArray[i].label, labelName) == 0) {
return labelArray[i].address;
}
}
return -1; // Label not found
}
void fillInLabelAddresses(intermediateElement *intermediateArray, int arraySize) {
for (int i = 0; i < arraySize; i++) {
// The Vector Segment is resolved separately. Most of what it holds is not a
// label at all: the words that name a vector are the segment's own, and looking
// them up here would report them as undefined.
if (intermediateArray[i].destination == VECTORS) {
continue;
}
if (intermediateArray[i].type == LABEL) {
// Look up the label in the label table
int address = findLabelAddress(intermediateArray[i].token);
if (address == -1) {
fprintf(stderr, RED "Error: Undefined label \"%s\".\n" RESET, intermediateArray[i].token);
printf("File: %s at line %d.\n", intermediateArray[i].fileName, intermediateArray[i].lineNumber);
exit(1);
}
// Assign the found address to the element
intermediateArray[i].address = address;
}
}
}
// Reports the type of the token following index i, or UNKNOWN if there isn't one.
// The operand checks go through this so that an instruction sitting at the very end of
// a program is reported as a missing operand instead of reading off the end of the array.
static int nextTokenType(intermediateElement *intermediateArray, int arraySize, int i) {
if (i + 1 >= arraySize) {
return UNKNOWN;
}
return intermediateArray[i + 1].type;
}
// Every instruction that reads operand bytes out of Program Memory needs those bytes to
// actually be there. If they aren't, the following instruction gets eaten as an operand
// and everything after it shifts, so these all have to be hard errors.
static void checkOperands(intermediateElement *intermediateArray, int arraySize, int i) {
uint8_t opcode = intermediateArray[i].byteValue;
int nextType = nextTokenType(intermediateArray, arraySize, i);
const char *problem = NULL;
// Listed rather than matched on the high nibble, because not every instruction in
// the branch block takes an address: RET has none, and BRD gets its destination
// from a Data Pointer instead of from the program.
if (opcode == 0x10 || opcode == 0x11 || opcode == 0x12 ||
opcode == 0x13 || opcode == 0x14 || opcode == 0x17) {
// Branches and CALL take a two byte address, which only a label can supply.
if (nextType != LABEL) problem = "Branch without label.";
} else if ((opcode & 0xF0) == 0xD0 || (opcode & 0xF0) == 0xE0) {
// The instruction is either an input or output and must be followed by a value.
if (nextType != VALUE) problem = "I/O without destination port.";
} else if (opcode == 0x18) {
// SWI names a vector, either by the name it was given in the Vector Segment or,
// rarely, as a literal number. Without one it swallows whatever follows it and
// every address after that shifts.
if (nextType != VECTOR_REFERENCE && nextType != VALUE) problem = "SWI without a vector to go to.";
} else if (opcode == 0x26 || opcode == 0x27) {
// INIA and INIB must be followed by the literal value to load.
if (nextType != VALUE) problem = "Immediate load without a value to load.";
} else if (opcode == 0x48 || opcode == 0x49) {
// DPUP and DPDN must be followed by the literal offset to apply.
if (nextType != VALUE) problem = "Data Pointer offset without an offset value.";
} else if (opcode == 0x47) {
// SETD takes a two byte address, as either a label or a pair of literal bytes.
if (nextType == VALUE) {
if (nextTokenType(intermediateArray, arraySize, i + 1) != VALUE) {
problem = "SETD given one literal byte, but an address is two bytes.";
}
} else if (nextType != LABEL) {
problem = "SETD without an address.";
}
}
if (problem) {
fprintf(stderr, RED "Error: %s\n" RESET, problem);
printf("File: %s at line %d.\n", intermediateArray[i].fileName, intermediateArray[i].lineNumber);
printf("Token: %s\n", intermediateArray[i].token);
exit(1);
}
}
void populateOutputBuffers(intermediateElement *intermediateArray, int arraySize, uint8_t *Program, int *programCount, uint8_t *Data, int *dataCount) {
for (int i = 0; i < arraySize; i++) {
if (intermediateArray[i].destination == PROGRAM) {
switch (intermediateArray[i].type) {
case INSTRUCTION:
// Add instruction byte to Program buffer.
Program[(*programCount)++] = intermediateArray[i].byteValue;
// Instructions that work through a Data Pointer carry a selector
// byte naming which one, whether or not the programmer wrote it.
for (int d = 0; d < dataPointerOperands(intermediateArray[i].byteValue); d++) {
Program[(*programCount)++] = intermediateArray[i].dataPointer[d];
}
// Make sure any operand bytes this instruction expects are present.
checkOperands(intermediateArray, arraySize, i);
break;
case VALUE:
// Add literal value to Program buffer.
Program[(*programCount)++] = intermediateArray[i].byteValue;
break;
case VECTOR_REFERENCE:
// A vector is a number rather than a place, so this is one byte
// where a label would be two.
Program[(*programCount)++] = intermediateArray[i].byteValue;
break;
case PADDING:
case ALIGNMENT:
for (int z = 0; z < intermediateArray[i].byteLength; z++) {
Program[(*programCount)++] = 0x00;
}
break;
case LABEL:
// Split 16-bit label address into high and low bytes.
Program[(*programCount)++] = (intermediateArray[i].address >> 8) & 0xFF; // High byte
Program[(*programCount)++] = intermediateArray[i].address & 0xFF; // Low byte
break;
}
} else if (intermediateArray[i].destination == DATA) {
switch (intermediateArray[i].type) {
case VALUE:
// Add literal value to Data buffer.
Data[(*dataCount)++] = intermediateArray[i].byteValue;
break;
case STRING:
// Copy string literal to Data buffer, including null terminator.
for (int j = 0; intermediateArray[i].token[j] != '\0'; j++) {
Data[(*dataCount)++] = intermediateArray[i].token[j];
}
Data[(*dataCount)++] = '\0'; // Add null terminator to Data buffer
break;
case LABEL:
// A label named in the Data Segment puts its address there, which is
// how a program lays down a table of addresses for LDD to walk.
// Two bytes, most significant first, the same order addresses are
// stored in everywhere else.
Data[(*dataCount)++] = (intermediateArray[i].address >> 8) & 0xFF; // High byte
Data[(*dataCount)++] = intermediateArray[i].address & 0xFF; // Low byte
break;
case PADDING:
case ALIGNMENT:
for (int z = 0; z < intermediateArray[i].byteLength; z++) {
Data[(*dataCount)++] = 0x00;
}
break;
}
}
}
}
void writeOutputFile(const char *outputFileName, uint8_t *Program, int programCount, uint8_t *Data, int dataCount) {
FILE *outputFile = fopen(outputFileName, "wb");
if (!outputFile) {
fprintf(stderr, RED "Error: Could not open file \"%s\" for writing.\n" RESET, outputFileName);
exit(1);
}
// Write the file header: the magic, the format version, and the features this
// binary needs from the machine. An emulator that cannot provide one of those
// features refuses the file rather than running it and going quietly wrong.
fwrite(SPLITBIT_MAGIC, sizeof(char), SPLITBIT_MAGIC_LENGTH, outputFile);
fputc(SPLITBIT_FORMAT_VERSION, outputFile);
uint32_t required = SPLITBIT_FEATURES_REQUIRED;
for (int i = SPLITBIT_FLAGS_LENGTH - 1; i >= 0; i--) {
fputc((required >> (i * 8)) & 0xFF, outputFile); // Most significant byte first.
}
// Write the "PRG" header for the program segment
fwrite("PRG", sizeof(char), SEGMENT_MARKER_LENGTH, outputFile);
// Write the program segment length as a 2-byte value (big-endian)
uint16_t programSize = programCount;
fputc((programSize >> 8) & 0xFF, outputFile); // High byte
fputc(programSize & 0xFF, outputFile); // Low byte
// Write the Program buffer to the file
if (fwrite(Program, sizeof(uint8_t), programCount, outputFile) != (size_t)programCount) {
fprintf(stderr, RED "Error: Failed to write Program data to file \"%s\".\n" RESET, outputFileName);
fclose(outputFile);
exit(1);
}
// Write the "DAT" header for the data segment
fwrite("DAT", sizeof(char), SEGMENT_MARKER_LENGTH, outputFile);
// Write the data segment length as a 2-byte value (big-endian)
uint16_t dataSize = dataCount;
fputc((dataSize >> 8) & 0xFF, outputFile); // High byte
fputc(dataSize & 0xFF, outputFile); // Low byte
// Write the Data buffer to the file
if (fwrite(Data, sizeof(uint8_t), dataCount, outputFile) != (size_t)dataCount) {
fprintf(stderr, RED "Error: Failed to write Data data to file \"%s\".\n" RESET, outputFileName);
fclose(outputFile);
exit(1);
}
// The Vector Segment, only if the program named any. Leaving it out entirely is
// what lets a binary written before vectors existed still load: the reader treats
// the end of the file as an empty table rather than a missing one.
int vectorBytes = 0;
if (vectorArrayCount > 0) {
fwrite("VEC", sizeof(char), SEGMENT_MARKER_LENGTH, outputFile);
vectorBytes = vectorArrayCount * VECTOR_ENTRY_FILE_BYTES;
fputc((vectorBytes >> 8) & 0xFF, outputFile);
fputc(vectorBytes & 0xFF, outputFile);
for (int i = 0; i < vectorArrayCount; i++) {
uint16_t slot = vectorArray[i].base + (uint16_t)vectorArray[i].index * VECTOR_ENTRY_BYTES;
fputc((slot >> 8) & 0xFF, outputFile);
fputc(slot & 0xFF, outputFile);
fputc((vectorArray[i].handler >> 8) & 0xFF, outputFile);
fputc(vectorArray[i].handler & 0xFF, outputFile);
}
}
fclose(outputFile);
printf("Successfully wrote SplitBit binary to \"%s\".\n", outputFileName);
printf(GREEN " Program Segment size: %d bytes.\n Data Segment size: %d bytes.\n" RESET, programCount, dataCount);
if (vectorArrayCount > 0) {
printf(GREEN " Vectors: %d.\n" RESET, vectorArrayCount);
}
printf(GREEN " Total size: %d bytes.\n" RESET,
(programCount + dataCount + SPLITBIT_HEADER_BYTES
+ (vectorArrayCount > 0 ? SEGMENT_MARKER_LENGTH + SEGMENT_LENGTH_BYTES + vectorBytes : 0)));
}
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