powerpc-bf1.c

/*
	Copyright 2015-2023 Rivoreo

	This Source Code Form is subject to the terms of the Mozilla Public
	License, v. 2.0. If a copy of the MPL was not distributed with this
	file, You can obtain one at https://mozilla.org/MPL/2.0/.
*/

#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <ctype.h>

#define LABEL_STACK_SIZE 1024

#ifndef DEFAULT_TARGET_BITS
#ifdef __powerpc64__
#define DEFAULT_TARGET_BITS 64
#else
#define DEFAULT_TARGET_BITS 32
#endif
#endif

#if DEFAULT_TARGET_BITS == 64
static int for_64bit = 1;
#else
static int for_64bit = 0;
#endif
static size_t buffer_size = 65536;

static int parse_extended_option(const char *o) {
	if(strcmp(o, "32") == 0) for_64bit = 0;
	else if(strcmp(o, "64") == 0) for_64bit = 1;
	else {
		// TODO: print error message
		return -1;
	}
	return 0;
}

static FILE *stdfopen(const char *path, const char *mode, const char **nice_name) {
	if(*path == '-') {
		const char *fdn = path + 1;
		if(!*fdn) {
			if(nice_name) *nice_name = *mode == 'r' ? "<stdin>" : "<stdout>";
			return *mode == 'r' ? stdin : stdout;
		}
		if(isdigit(*fdn)) {
			char *end_p;
			int fd = strtol(fdn, &end_p, 10);
			if(!*end_p && fd >= 0) {
				if(nice_name) switch(fd) {
					case STDIN_FILENO:
						*nice_name = "<stdin>";
						break;
					case STDOUT_FILENO:
						*nice_name = "<stdout>";
						break;
					case STDERR_FILENO:
						*nice_name = "<stderr>";
						break;
					default:
						*nice_name = "<fd>";
						break;
				}
				return fdopen(fd, mode);
			}
		}
	}
	if(nice_name) *nice_name = path;
	return fopen(path, mode);
}

static void print_buffer_code(FILE *f) {
	fprintf(f, "	.lcomm	buffer, %zu\n", buffer_size);
}

static void print_startup_code(FILE *f) {
	fputs(for_64bit ?
		"	.align	2\n"
		"	.section	.opd, \"aw\"\n"
		"	.global	_start\n"
		"_start:\n"
		"	.quad	start, .TOC.@tocbase, 0\n"
		"	.previous\n"
		"start:\n"
		"	addis	%r14, %r2, buffer@toc@ha\n"
		"	la	%r14, buffer@toc@l(%r14)\n"
		:
		"	.align	2\n"
		"	.global	_start\n"
		"_start:\n"
		"	lis	%r14, buffer@ha\n"
		"	la	%r14, buffer@l(%r14)\n",
		f
	);
}

static void add_ptr(FILE *f, int offset) {
	fprintf(f, "	addi	%%r14, %%r14, %d\n", offset);
}

static void add_data(FILE *f, int offset) {
	fprintf(f,
		"	lbz	%%r10, 0(%%r14)\n"
		"	addi	%%r10, %%r10, %d\n"
		"	stb	%%r10, 0(%%r14)\n",
		offset);
}

static void read_data(FILE *f) {
	fputs(
		"	li	%r5, 1\n"
		"	mr	%r4, %r14\n"
		"	li	%r3, 0\n"
		"	li	%r0, 3\n"
		"	sc\n"
		"	bso	fail\n",
		f
	);
}

static void write_data(FILE *f) {
	fputs(
		"	li	%r5, 1\n"
		"	mr	%r4, %r14\n"
		"	li	%r3, 1\n"
		"	li	%r0, 4\n"
		"	sc\n"
		"	bso	fail\n",
		f
	);
}

static void check_ptr_state(FILE *f, int *state) {
	if(!*state) return;
	add_ptr(f, *state);
	*state = 0;
}

static int check_data_state(FILE *f, int *state) {
	if(!*state) return 0;
	add_data(f, *state);
	*state = 0;
	return 1;
}

static int compile(const char *input_file_name, FILE *input_file, FILE *output_file, int debug, int optimize_level) {
	int ptr_state = 0;
	int data_state = 0;
	int label_stack[LABEL_STACK_SIZE];
	int label_stack_i = -1;
	int label_i = 0;
	int nlines = 1;
	int c;
	if(debug) {
		fprintf(output_file,
			"	.file	1 \"%s\"\n"
			"	.loc	1 1\n",
			input_file_name);
	}
	while((c = fgetc(input_file)) != EOF) switch(c) {
			int data_cached;
		case '<':
			if(optimize_level == '0') {
				fputs("	subi	%r14, %r14, 1\n", output_file);
			} else {
				check_data_state(output_file, &data_state);
				ptr_state--;
			}
			break;
		case '>':
			if(optimize_level == '0') {
				fputs("	addi	%r14, %r14, 1\n", output_file);
			} else {
				check_data_state(output_file, &data_state);
				ptr_state++;
			}
			break;
		case '-':
		case '+':
			if(optimize_level == '0') {
				add_data(output_file, c == '-' ? -1 : 1);
			} else {
				check_ptr_state(output_file, &ptr_state);
				data_state += c == '-' ? -1 : 1;
			}
			break;
		case ',':
		case '.':
			if(optimize_level != '0') {
				check_ptr_state(output_file, &ptr_state);
				check_data_state(output_file, &data_state);
			}
			(c == ',' ? read_data : write_data)(output_file);
			break;
		case '[':
			if(optimize_level == '0') {
				data_cached = 0;
			} else {
				check_ptr_state(output_file, &ptr_state);
				data_cached = check_data_state(output_file, &data_state);
			}
			fprintf(output_file,
				"	%s\n"
				"	cmpwi	%%cr7, %%r10, 0\n"
				"	beq	%%cr7, .l%d_end\n"
				".l%d_begin:\n",
				data_cached ? "rlwinm	%r10, %r10, 0, 0xff" : "lbz	%r10, 0(%r14)",
				label_i, label_i);
			label_stack[++label_stack_i] = label_i++;
			break;
		case ']':
			if(label_stack_i < 0) {
				fprintf(stderr, "%s:%d: error: no '[' to match ']'\n", input_file_name, nlines);
				return -1;
			}
			if(optimize_level == '0') {
				data_cached = 0;
			} else {
				check_ptr_state(output_file, &ptr_state);
				data_cached = check_data_state(output_file, &data_state);
			}
			int i = label_stack[label_stack_i];
			fprintf(output_file,
				"	%s\n"
				"	cmpwi	%%cr7, %%r10, 0\n"
				"	bne	%%cr7, .l%d_begin\n"
				".l%d_end:\n",
				data_cached ? "rlwinm	%r10, %r10, 0, 0xff" : "lbz	%r10, 0(%r14)",
				i, i);
			label_stack_i--;
			break;
		case '\n':
			nlines++;
			if(debug) {
				if(optimize_level == 'g') {
					check_ptr_state(output_file, &ptr_state);
					check_data_state(output_file, &data_state);
				}
				fprintf(output_file, "	.loc	1 %d\n", nlines);
			}
			break;
	}
	if(label_stack_i >= 0) {
		fprintf(stderr, "%s: error: no ']' to match %d previous '['\n", input_file_name, label_stack_i + 1);
		return -1;
	}
	/* Ignoring unfinished states, they are being eliminated as a part of
	 * optimization.
	 */
	return 0;
}

static void print_exit_code(FILE *f) {
	fputs(
		"	li	%r3, 0\n"
		"exit:\n"
		"	li	%r0, 1\n"
		"	sc\n"
		"fail:\n"
		"	li	%r3, 1\n"
		"	b	exit\n",
		f
	);
}

int main(int argc, char **argv) {
	int debugging = 0;
	int optimize_level = '0';
	const char *output_path = NULL;
	int verbose = 0;
	const char *input_file_name;
	FILE *input_file = NULL;
	int end_of_options = 0;
	int i = 1;
	while(i < argc) {
		if(!end_of_options && argv[i][0] == '-') {
			const char *o = argv[i] + 1;
			if(!*o) goto not_an_option;
			if(*o == '-') {
				if(o[1]) {
					fprintf(stderr, "%s: Invalid option '%s'\n", argv[0], argv[i]);
					return -1;
				}
				end_of_options = 1;
			} else switch(*o) {
				case '0' ... '9':
					goto not_an_option;
				case 'g':
					debugging = 1;
					break;
				case 'O':
					if(o[1]) optimize_level = o[1];
					else if(++i >= argc) {
						fprintf(stderr, "%s: Option '-O' requires an argument\n", argv[0]);
						return -1;
					} else optimize_level = *argv[i];
					break;
				case 'q':
					if(++i >= argc) {
						fprintf(stderr, "%s: Option '-q' requires an argument\n", argv[0]);
						return -1;
					}
					if(parse_extended_option(argv[i]) < 0) return -1;
					break;
				case 'o':
					if(++i >= argc) {
						fprintf(stderr, "%s: Option '-o' requires an argument\n", argv[0]);
						return -1;
					}
					output_path = argv[i];
					break;
				case 'v':
					verbose = 1;
					break;
				default:
					fprintf(stderr, "%s: Invalid option '-%c'\n", argv[0], *o);
					return -1;
			}
		} else {
not_an_option:
			if(input_file) {
				fprintf(stderr, "%s: Only 1 input file can be specified\n", argv[0]);
				return -1;
			}
			input_file = stdfopen(argv[i], "r", &input_file_name);
			if(!input_file) {
				perror(argv[i]);
				return 1;
			}
		}
		i++;
	}

	if(!input_file) {
		input_file_name = "<stdin>";
		input_file = stdin;
	}

	FILE *output_file;
	if(output_path) {
		output_file = stdfopen(output_path, "w", NULL);
		if(!output_file) {
			perror(output_path);
			return 1;
		}
	} else {
		output_file = stdout;
	}

	fputs("	.text\n", output_file);
	print_buffer_code(output_file);
	print_startup_code(output_file);
	if(compile(input_file_name, input_file, output_file, debugging, optimize_level) < 0) return 1;
	print_exit_code(output_file);
	fclose(output_file);
	return 0;
}