58 lines
1.3 KiB
C
58 lines
1.3 KiB
C
#include <acpi.h>
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#include <strcmp.h>
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struct rsdp *acpi_locate_rsdp() {
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char *ptr = (char *)BIOS_START;
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char *str = RSDP_SIG;
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while ((uint32_t)ptr <= (uint32_t)BIOS_END - RSDP_SIG_LEN) {
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int i;
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for (i = 0; i < RSDP_SIG_LEN; i++) {
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if (ptr[i] != str[i])
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break;
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}
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if (i == RSDP_SIG_LEN) {
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return (struct rsdp *)ptr;
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}
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ptr++;
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}
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return 0;
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}
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int acpi_validate_rsdp_checksum(struct rsdp *s) {
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uint8_t *bytes = (uint8_t *)s;
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uint8_t sum = 0;
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for (int i = 0; i < RSDP_SIZE; i++) {
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sum += bytes[i];
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}
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return (sum & 0x0F) == 0;
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}
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int acpi_validate_sdt_checksum(struct ACPISDTHeader *s) {
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uint8_t sum = 0;
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for (uint32_t i = 0; i < s->Length; i++) {
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sum += ((char *)s)[i];
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}
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return sum == 0;
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}
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void *acpi_locate_sdt(struct rsdt *rsdt, const char sig[4]) {
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int entries = (rsdt->h.Length - sizeof(rsdt->h)) / 4;
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for (int i = 0; i < entries; i++)
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{
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struct ACPISDTHeader *h = (struct ACPISDTHeader *) rsdt->other_sdt[i];
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if (!strncmp(h->Signature, sig, 4)) {
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if (acpi_validate_sdt_checksum(h))
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return (void *) h;
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else
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return 0;
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}
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}
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return 0;
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}
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