symbol.c File Reference

#include "symbol.h"
#include "../common.h"
#include "../encode.h"
#include "exception.h"
#include "util.h"
#include <stdlib.h>
#include <string.h>

Functions
int	c8_build_instruction (C8_Instruction *ins, C8_SymbolList *symbols, int idx)
	Build an instruction from symbols beginning at idx.
int	c8_is_comment (const char *s)
	Check if the given string is a comment.
int	c8_is_db (const char *s)
	Check if given string is a DB identifier.
int	c8_is_ds (const char *s)
	Check if given string is a DS identifier.
int	c8_is_dw (const char *s)
	Check if given string is a DW identifier.
int	c8_is_instruction (const char *s)
	Check if the given string is an instruction.
int	c8_is_label_definition (const char *s)
	Check if the given string is a label definition.
int	c8_is_label (const char *s, const C8_LabelList *labels)
	Check if given string is a label reference.
int	c8_is_register (const char *s)
	Check if the given string represents a V register.
int	c8_is_reserved_identifier (const char *s)
	Check if given string is a reserved identifier.
C8_Symbol *	c8_next_symbol (C8_SymbolList *symbols)
	Get the next symbol.
int	c8_populate_labels (C8_LabelList *labels)
	Populate label list from lines.
int	c8_resolve_labels (C8_SymbolList *symbols, C8_LabelList *labels)
	Get byte indexes of label definitions from completed symbol table.
int	c8_substitute_labels (C8_SymbolList *symbols, C8_LabelList *labels)
	Substitute label symbols with their corresponding int value.
int	c8_shift (uint16_t fmt)
	Find the bits needed to shift to OR a parameter into an instruction.

Variables
const char *	c8_identifierStrings []
const char *	c8_instructionStrings []
C8_InstructionFormat	c8_formats []

Detailed Description

Note

NOT EXPORTED

Stuff for parsing symbols and instructions for encoding CHIP-8 "assembly".

Function Documentation

c8_build_instruction()

int c8_build_instruction	(	C8_Instruction *	ins,
		C8_SymbolList *	symbols,
		int	idx
	)

Build an instruction from symbols beginning at idx.

This function builds an instruction from a completely parsed set of symbols (with labels expanded).

Parameters

ins	instruction_t to store instruction contents
symbols	symbol list
idx	symbols index of start of instruction

Returns

instruction bytecode

c8_is_comment()

int c8_is_comment

(

const char *

s

)

Check if the given string is a comment.

Parameters

s	the string to check

Returns

1 if true, 0 if false

c8_is_db()

int c8_is_db

(

const char *

s

)

Check if given string is a DB identifier.

Returns

1 if true, 0 if false

c8_is_ds()

int c8_is_ds

(

const char *

s

)

Check if given string is a DS identifier.

Returns

1 if true, 0 if false

c8_is_dw()

int c8_is_dw

(

const char *

s

)

Check if given string is a DW identifier.

Returns

1 if true, 0 if false

c8_is_instruction()

int c8_is_instruction

(

const char *

s

)

Check if the given string is an instruction.

Parameters

s	the string to check

Returns

instruction enumerator if true, -1 if false

c8_is_label()

int c8_is_label	(	const char *	s,
		const C8_LabelList *	labels
	)

Check if given string is a label reference.

This function checks if the given string is a label reference by comparing it against the label list. It returns the index of the label in the label list if it is found, or -1 if it is not.

This function assumes that the label list has been populated (e.g. populate_labels() has been called).

Parameters

s	string to check
labels	label list to check from

Returns

label index if true, -1 otherwise

c8_is_label_definition()

int c8_is_label_definition

(

const char *

s

)

Check if the given string is a label definition.

Parameters

s	the string to check

Returns

1 if true, 0 if false

c8_is_register()

int c8_is_register

(

const char *

s

)

Check if the given string represents a V register.

This function checks if the given string starts with 'V' or 'v' and is followed by a valid hexadecimal digit (0-9, A-F, a-f). It returns the register number if it is a valid V register, or -1 if it is not.

Parameters

s	string to check

Returns

V register number if true, -1 otherwise

c8_is_reserved_identifier()

int c8_is_reserved_identifier

(

const char *

s

)

Check if given string is a reserved identifier.

This function checks if the given string is one of the reserved identifiers defined in c8_identifierStrings. It returns the index of the identifier if it is found, or -1 if it is not.

Parameters

s	string to check

Returns

type of identifier if true, -1 otherwise

c8_next_symbol()

C8_Symbol * c8_next_symbol

(

C8_SymbolList *

symbols

)

Get the next symbol.

This function retrieves the next available symbol in the symbol list. If the symbol list is empty, it initializes the first symbol. If the symbol list is full, it reallocates the symbol list to accommodate more symbols.

If symbols is NULL or the symbol list is NULL, it returns NULL.

Parameters

symbols

symbol list to get next symbol from

Returns

first empty symbol in symbol table

c8_populate_labels()

int c8_populate_labels

(

C8_LabelList *

labels

)

Populate label list from lines.

This function scans through the lines of code and identifies label definitions. It checks each line for a label definition (ending with a colon) and adds it to the label list.

If a duplicate label definition is found, it throws a C8_DUPLICATE_LABEL_EXCEPTION.

If too many labels are defined, it throws a C8_TOO_MANY_LABELS_EXCEPTION.

Parameters

labels

label list to populate

Returns

1 if success, 0 or error code otherwise

c8_resolve_labels()

int c8_resolve_labels	(	C8_SymbolList *	symbols,
		C8_LabelList *	labels
	)

Get byte indexes of label definitions from completed symbol table.

This function resolves label definitions in the symbol list and populates the label list with the byte index of each label definition. It iterates through the symbols, keeping track of the current byte position in the program. When it encounters a label definition, it records the current byte position in the label list. It also increments the byte position based on the type of symbol encountered (e.g., SYM_DB increments by 1, SYM_INSTRUCTION and SYM_DW increment by 2).

This function assumes that the symbol list has been populated and that the symbols have been parsed correctly. It also assumes that the label list has been initialized.

This function will return 1 if all labels were resolved successfully, or 0 if there was a failure (e.g., if the label list is not fully populated).

Parameters

symbols	list of symbols
labels	list of labels

Returns

1 if success, 0 if failure

c8_shift()

int c8_shift

(

uint16_t

fmt

)

Find the bits needed to shift to OR a parameter into an instruction.

This function finds the bits needed to shift to OR a parameter into an instruction. It is used to determine the position of parameters in the instruction bytecode.

This is a workaround for the fact that the instruction formats are not defined in a way that allows for easy bit manipulation.

Parameters

fmt	C8_InstructionFormat pformat to check

Returns

number of bits to shift

c8_substitute_labels()

int c8_substitute_labels	(	C8_SymbolList *	symbols,
		C8_LabelList *	labels
	)

Substitute label symbols with their corresponding int value.

This function replaces all symbols of type C8_SYM_LABEL in the symbol list with their corresponding byte value from the label list. It checks if the label exists and throws an C8_INVALID_SYMBOL_EXCEPTION if it does not.

This function assumes that the label list has been populated and that their byte values have been set correctly.

Parameters

symbols	symbols to search
labels	labels to search

Variable Documentation

c8_formats

C8_InstructionFormat c8_formats[]

All valid instruction formats

c8_identifierStrings

const char* c8_identifierStrings[]

Initial value:

= {
    "",      "DT" ,  "ST" ,  "I" ,   "[I]" ,  "K" ,  "F" ,
     "B" ,  ".DB" ,  ".DW" ,  ".DS" ,  "HF" ,  "R" , NULL,
}

Reserved identifier strings. Has to match Symbol.

c8_instructionStrings

const char* c8_instructionStrings[]

Initial value:

= {
     "CLS" ,  "RET" ,  "JP" ,   "CALL" ,  "SE" ,    "SNE" ,  "LD" ,    "ADD" ,    "OR" ,
     "AND" ,  "SUB" ,  "SHR" ,  "SUBN" ,  "SHL" ,   "RND" ,  "DRW" ,   "SKP" ,    "SKNP" ,
     "XOR" ,  "SCD" ,  "SCR" ,  "SCL" ,   "EXIT" ,  "LOW" ,  "HIGH" ,  "JP V0," , NULL,
}

Instruction strings. Has to match Instruction.