122 lines
3.0 KiB
C
122 lines
3.0 KiB
C
/* SPDX-FileCopyrightText: 2022 Andrius Štikonas <andrius@stikonas.eu>
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*
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* SPDX-License-Identifier: GPL-3.0-or-later */
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/* Written in a low level C that is close to assembly.
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* We skip error checking since this is a prototype for hex0 code */
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#include "efi/efi.h"
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efi_status_t efi_main(efi_handle_t image_handle, struct efi_system_table *system)
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{
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struct efi_loaded_image_protocol *image;
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struct efi_simple_file_system_protocol *rootfs;
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struct efi_file_protocol *rootdir;
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struct efi_guid guid1 = EFI_LOADED_IMAGE_PROTOCOL_GUID;
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struct efi_guid guid2 = EFI_SIMPLE_FILE_SYSTEM_PROTOCOL_GUID;
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/* Open Loaded Image protocol */
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system->boot->open_protocol(image_handle, &guid1, (void **) &image, image_handle, 0,
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EFI_OPEN_PROTOCOL_BY_HANDLE_PROTOCOL);
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/* Command line args */
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uint16_t *options = image->load_options;
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uint16_t *in;
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uint16_t *out;
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do {
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++options;
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} while (*options != ' '); /* Skip app name */
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in = ++options;
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do {
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++options;
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} while (*options != ' ');
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*options = 0;
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out = ++options;
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/* Get root device */
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efi_handle_t root_device = image->device;
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system->boot->open_protocol(root_device, &guid2, (void **) &rootfs, image_handle, 0,
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EFI_OPEN_PROTOCOL_BY_HANDLE_PROTOCOL);
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/* Get root fs */
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rootfs->open_volume(rootfs, &rootdir);
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/* Open file for reading */
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struct efi_file_protocol *fin;
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rootdir->open(rootdir, &fin, in, EFI_FILE_MODE_READ, EFI_FILE_READ_ONLY);
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/* Open file for writing */
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struct efi_file_protocol *fout;
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rootdir->open(rootdir, &fout, out, EFI_FILE_MODE_CREATE| EFI_FILE_MODE_WRITE | EFI_FILE_MODE_READ, 0);
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uint8_t c;
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uint64_t size;
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uint8_t toggle = 0;
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uint8_t hold;
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next_byte:
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size = 1;
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fin->read(fin, &size, &c);
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/* If the file ended (0 bytes read) terminate */
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if (size == 0) {
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goto terminate;
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}
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/* Check if it's a comment */
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if (c == '#' || c == ';') {
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goto loop;
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}
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goto not_comment;
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loop:
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fin->read(fin, &size, &c);
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/* If the file ended (0 bytes read) terminate */
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if (size == 0) {
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goto terminate;
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}
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/* Check if read byte is the end of the comment (i.e. a newline character),
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* in that case we continue processing */
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if (c == '\n' || c == '\r') {
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goto next_byte;
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}
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goto loop;
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not_comment:
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/* Check if it's a hex character:
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* in the case it's not, ignores and reads next byte */
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if (c >= '0' && c <= '9') {
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c -= 48;
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}
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else if (c >= 'A' && c <= 'F') {
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c -= 55;
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}
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else if (c >= 'a' && c <= 'f') {
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c -= 87;
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}
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else {
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goto next_byte;
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}
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if (!toggle) {
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hold = c;
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toggle = 1;
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}
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else {
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c = (hold << 4) + c;
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fout->write(fout, &size, &c);
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hold = 0;
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toggle = 0;
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}
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goto next_byte;
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terminate:
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/* rootdir->close(fin);
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rootdir->close(fout); */
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return 0;
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}
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