acme/src/encoding.c

142 lines
3.3 KiB
C
Raw Normal View History

// ACME - a crossassembler for producing 6502/65c02/65816 code.
// Copyright (C) 1998-2014 Marco Baye
// Have a look at "acme.c" for further info
//
// Character encoding stuff
#include <stdio.h>
#include <string.h>
#include "alu.h"
#include "acme.h"
#include "dynabuf.h"
#include "encoding.h"
#include "global.h" // FIXME - remove when no longer needed
#include "output.h"
#include "pseudoopcodes.h" // FIXME - remove when no longer needed
#include "input.h"
#include "tree.h"
// struct definition
struct encoder {
char (*fn)(char);
// maybe add table pointer?
};
// variables
static char outermost_table[256]; // space for encoding table...
const struct encoder *encoder_current; // gets set before each pass
char *encoding_loaded_table = outermost_table; // ...loaded from file
// encoder functions:
// convert raw to raw (do not convert at all)
static char encoderfn_raw(char byte)
{
return byte;
}
// convert raw to petscii
static char encoderfn_pet(char byte)
{
if ((byte >= 'A') && (byte <= 'Z'))
return (char) (byte | 0x80); // FIXME - check why SAS-C
if ((byte >= 'a') && (byte <= 'z')) // wants these casts.
return (char) (byte - 32); // There are more below.
return byte;
}
// convert raw to C64 screencode
static char encoderfn_scr(char byte)
{
if ((byte >= 'a') && (byte <= 'z'))
return (char) (byte - 96); // shift uppercase down
if ((byte >= '[') && (byte <= '_'))
return (char) (byte - 64); // shift [\]^_ down
if (byte == '`')
return 64; // shift ` down
if (byte == '@')
return 0; // shift @ down
return byte;
}
// convert raw to whatever is defined in table
static char encoderfn_file(char byte)
{
return encoding_loaded_table[(unsigned char) byte];
}
// predefined encoder structs:
const struct encoder encoder_raw = {
encoderfn_raw
};
const struct encoder encoder_pet = {
encoderfn_pet
};
const struct encoder encoder_scr = {
encoderfn_scr
};
const struct encoder encoder_file = {
encoderfn_file
};
// keywords for "!convtab" pseudo opcode
static struct ronode *encoder_tree = NULL; // tree to hold encoders
static struct ronode encoder_list[] = {
//no! PREDEFNODE("file", &encoder_file), "!ct file" is not needed; just use {} after initial loading of table!
PREDEFNODE(s_pet, &encoder_pet),
PREDEFNODE(s_raw, &encoder_raw),
PREDEFLAST(s_scr, &encoder_scr),
// ^^^^ this marks the last element
};
// exported functions
// convert character using current encoding (exported for use by alu.c and pseudoopcodes.c)
char encoding_encode_char(char byte)
{
return encoder_current->fn(byte);
}
// set "raw" as default encoding
void encoding_passinit(void)
{
encoder_current = &encoder_raw;
}
// try to load encoding table from given file
void encoding_load(char target[256], const char *filename)
{
FILE *fd = fopen(filename, FILE_READBINARY);
if (fd) {
if (fread(target, sizeof(char), 256, fd) != 256)
Throw_error("Conversion table incomplete.");
fclose(fd);
} else {
Throw_error(exception_cannot_open_input_file);
}
}
// lookup encoder held in DynaBuf and return its struct pointer (or NULL on failure)
const struct encoder *encoding_find(void)
{
void *node_body;
// make sure tree is initialised
if (encoder_tree == NULL)
Tree_add_table(&encoder_tree, encoder_list);
// perform lookup
if (!Tree_easy_scan(encoder_tree, &node_body, GlobalDynaBuf)) {
Throw_error("Unknown encoding.");
return NULL;
}
return node_body;
}