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Replace bios with bootloader, don't use bootsector

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Instead of using the bootsector to load a bootloader, just put the
bootloader in the ROM and call it a day. It looks for a file on the SD
card in the root directory named `kernel.bin` and loads it into memory.

This is not a perfect solution, as the kernel will grow larger and the
kernel load address will have to change. At this point I could add back
the bootloader, but that is for later.

Also the bootloader is just a copy of the kernel, so that can be trimmed
down a lot.
This commit is contained in:
Byron Lathi
2022-04-19 10:34:19 -05:00
parent f664d59497
commit f3c7ac9696
42 changed files with 1295 additions and 232 deletions
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124
sw/bootloader/filesystem/fat.h Normal file
View File

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#ifndef _FAT_H
#define _FAT_H
#include <stdint.h>
extern uint8_t fat_buf[];
#define FAT_MAX_FILE_NAME 255
#define FAT_CLUSTERS_PER_SECTOR 128
#define FAT_CLUSTERMASK 0x0fffffff
#define FAT_EOC_CLUSTERMASK 0x0ffffff8
#define FAT_LAST_LFN_MASK (1 << 6)
#define FAT_LFN_ENTRY_MASK 0x1f
typedef struct {
uint16_t bytes_per_sector;
uint8_t sectors_per_cluster;
uint16_t reserved_sectors;
uint8_t fat_count;
uint16_t max_dir_entries;
uint16_t total_sector_count;
uint8_t media_descriptor;
uint16_t sectors_per_fat;
} dos_2_bpb_t;
typedef struct {
dos_2_bpb_t bpb2;
uint16_t sectors_per_track;
uint16_t head_count;
uint32_t hidden_sector_count;
uint32_t logical_sector_count;
uint32_t sectors_per_fat;
uint16_t extended_flags;
uint16_t version;
uint32_t root_cluster;
uint16_t system_information;
uint16_t backup_boot_sector;
uint8_t reserved[12];
} dos_3_bpb_t;
typedef struct {
dos_3_bpb_t bpb3;
uint8_t drive_num;
uint8_t reserved;
uint8_t extended_signature;
uint32_t volume_id;
uint8_t partition_label[11];
uint8_t filesystem_type[8];
} ebpb_t;
typedef struct {
uint16_t bytes_per_sector;
uint8_t sectors_per_cluster;
uint16_t reserved_sectors;
uint8_t fat_count;
uint16_t max_dir_entries;
uint16_t total_sector_count;
uint8_t media_descriptor;
uint16_t sectors_per_fat_16;
uint16_t sectors_per_track;
uint16_t head_count;
uint32_t hidden_sector_count;
uint32_t logical_sector_count;
uint32_t sectors_per_fat_32;
uint16_t extended_flags;
uint16_t version;
uint32_t root_cluster;
uint16_t system_information;
uint16_t backup_boot_sector;
uint8_t reserved[12];
uint8_t drive_num;
uint8_t reserved2;
uint8_t extended_signature;
uint32_t volume_id;
uint8_t partition_label[11];
uint8_t filesystem_type[8];
} full_bpb_t;
typedef struct {
uint32_t sig;
uint8_t reserved[480];
uint32_t sig2;
uint32_t free_data_clusters;
uint32_t last_allocated_data_cluster;
uint32_t reserved2;
uint32_t sig3;
} fs_info_sector_t;
typedef struct {
uint8_t sequence_number;
uint16_t filename0[5];
uint8_t attributes;
uint8_t type;
uint8_t checksum;
uint16_t filename1[6];
uint16_t reserved;
uint16_t filename2[2];
} vfat_dentry_t;
typedef struct {
uint8_t filename[8];
uint8_t extension[3];
uint8_t attributes;
uint8_t reserved;
uint8_t create_time_10ms;
uint32_t create_date;
uint16_t access_date;
uint16_t first_cluster_h;
uint32_t modify_cluster;
uint16_t first_cluster_l;
uint32_t file_size;
} dos_dentry_t;
void fat_print_pbp_info(full_bpb_t* bpb);
void fat_init();
void fat_read(char* filename, void* buf);
uint16_t fat_parse_path_to_cluster(char* filename);
void fat_read_cluster(uint16_t cluster, uint8_t* buf);
uint32_t fat_get_chain_value(uint16_t cluster);
#endif