82 lines
1.8 KiB
C
82 lines
1.8 KiB
C
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#include <multiboot.h>
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#include <acpi.h>
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struct kernel_context {
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struct rsdp *rsdp;
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struct xsdp *xsdp;
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struct rsdt *rsdt;
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};
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struct kernel_context ctx = {0};
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int strncmp( const char * s1, const char * s2, int n )
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{
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while ( n && *s1 && ( *s1 == *s2 ) )
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{
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++s1;
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++s2;
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--n;
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}
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if ( n == 0 )
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{
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return 0;
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}
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else
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{
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return ( *(unsigned char *)s1 - *(unsigned char *)s2 );
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}
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}
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void *findFACP(void *RootSDT)
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{
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struct rsdt *rsdt = (struct rsdt *) RootSDT;
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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, "FACP", 4))
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return (void *) h;
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}
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// No FACP found
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return 0;
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}
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void kmain(struct multiboot_info *info) {
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// Check if the bootloader gave us the upper and lower memory
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if (!(info->flags & 0x1)) goto halt;
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char *vmem = (char *)0xb8000;
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struct rsdp *found_rsdp = acpi_search_for_rsdp();
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if (!found_rsdp) goto halt;
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if (found_rsdp->Revision == ACPI_VER_1) {
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// ACPI v1.0 is being used
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if (!acpi_validate_rsdp_checksum(found_rsdp)) goto halt;
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ctx.rsdp = found_rsdp;
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ctx.xsdp = 0;
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if (!acpi_validate_sdt_checksum((struct ACPISDTHeader *)found_rsdp->RsdtAddress))
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goto halt;
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ctx.rsdt = (struct rsdt*)found_rsdp->RsdtAddress;
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} else if (found_rsdp->Revision == ACPI_VER_OTHER) {
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// ACPI v2.0+ is being used
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// not supported yet....
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goto halt;
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} else goto halt;
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void *fadt = findFACP(ctx.rsdt);
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if (!fadt) goto halt;
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char *next_sig = (char *)fadt;
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vmem[0] = next_sig[0];
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vmem[2] = next_sig[1];
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vmem[4] = next_sig[2];
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vmem[6] = next_sig[3];
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halt:
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for (;;) {}
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}
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