92 lines
2.3 KiB
C
92 lines
2.3 KiB
C
#include <endianness.h>
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#include <string.h>
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#include <fxos.h>
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#include <errors.h>
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#include <util.h>
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/* os_load(): Load an OS file and find out basic properties */
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int os_load(char const *path, struct os *os)
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{
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if(!path || !os) return 1;
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os->data = map(path, &os->fd, &os->len);
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if(!os->data) return 1;
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if(os->len < 0x10080)
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{
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err("too small for the OS format I know (min. 0x10080 bytes)",
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os->len);
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return 1;
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}
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/* Get the OS version */
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memcpy(os->version, os->data + 0x10020, 14);
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os->version[14] = 0;
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/* Guess the MPU type (or assume SH7305). Until version 03.00, the last
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digit of the version number indicated the presence of an SH7305 */
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os->mpu = MPU_SH7305;
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if(!strncmp(os->version, "02.", 3) && os->version[13] == '0')
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os->mpu = MPU_SH7705;
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/* Find the syscall table address */
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memcpy(&os->syscall_table, os->data + 0x1007c, 4);
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os->syscall_table = be32toh(os->syscall_table);
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/* Count the number of valid syscall entries */
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os->syscalls = 0;
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while(memory_region(os_syscall(os, os->syscalls))) os->syscalls++;
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/* Find the footer address (last occurrence of "CASIOABSLangdata") */
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char const *signature = "CASIOABSLangdata";
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void *occ = NULL, *next = memmem(os->data, os->len, signature, 16);
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void *end = os->data + os->len;
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while(next)
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{
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occ = next;
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next = memmem(next + 1, end - (next + 1), signature, 16);
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}
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os->footer = (occ) ? (occ - os->data) : (uint32_t)-1;
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return 0;
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}
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/* os_syscall(): Get the address of a syscall entry */
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uint32_t os_syscall(struct os const *os, int syscall)
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{
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uint32_t table_entry = (os->syscall_table & 0x1fffffff) + 4 * syscall;
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if(table_entry + 4 > os->len) return (uint32_t)-1;
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uint32_t address;
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memcpy(&address, os->data + table_entry, 4);
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address = be32toh(address);
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return address;
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}
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/* os_syscall_find(): Find a syscall which points to an address */
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int os_syscall_find(struct os const *os, uint32_t entry)
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{
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/* Try to make this slightly quicker */
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uint32_t table_entry = (os->syscall_table & 0x1fffffff);
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entry = htobe32(entry);
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uint32_t *entries = os->data + table_entry;
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for(int i = 0; i < os->syscalls; i++) if(entries[i] == entry) return i;
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return -1;
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}
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/* os_free(): Free an OS file opened with os_load() */
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void os_free(struct os const *os)
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{
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if(os && os->data) unmap(os->data, os->fd, os->len);
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}
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