From 30d6e8f850d2fe26fffdeef0c38fc627ef8bab9a Mon Sep 17 00:00:00 2001
From: "Anna (navi) Figueiredo Gomes" <navi@vlhl.dev>
Date: Wed, 13 Dec 2023 13:24:48 +0100
Subject: initial commit

currently with:
booted via multiboot 1
protected mode to long mode boostrap code
vga used for outputting
gdt and idt set up
identity paging for the whole memory reported by multiboot
pic and ps/2 set up
acpi code exists but is broken
---
 src/acpi.c | 84 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 84 insertions(+)
 create mode 100644 src/acpi.c

(limited to 'src/acpi.c')

diff --git a/src/acpi.c b/src/acpi.c
new file mode 100644
index 0000000..b4bb05e
--- /dev/null
+++ b/src/acpi.c
@@ -0,0 +1,84 @@
+#include <acpi.h>
+#include <vga.h>
+#include <mem.h>
+#include <stdbool.h>
+
+static bool checksum_rsdp(const struct rsdp *rsdp) {
+	size_t chksm = 0;
+	for (uint8_t *byte = (uint8_t*) rsdp; byte < (uint8_t*)rsdp + sizeof(*rsdp); byte++)
+		chksm += *byte;
+	return (chksm & 0xFF) == 0;
+}
+
+static bool checksum_xsdp(const struct xsdp *rsdp) {
+	return true;
+	size_t chksm = 0;
+	for (uint8_t *byte = (uint8_t*) rsdp; byte < (uint8_t*)rsdp + sizeof(*rsdp); byte++)
+		chksm += *byte;
+	return (chksm & 0xFF) == 0;
+}
+
+static bool checksum_sdt(const struct acpi_sdt_header *header) {
+	uint8_t chksm = 0;
+	for (size_t i = 0; i < header->len; i++) {
+		chksm += ((int8_t *) header)[i];
+	}
+	return chksm == 0;
+}
+
+void print_rsdp(const struct rsdp *rsdp) {
+	vga_puts("sig: ");
+	vga_putsn(rsdp->signature, 8);
+	vga_putc('\n');
+
+	vga_puts("checksum: ");
+	vga_putn(rsdp->checksum);
+	vga_putc(' ');
+	vga_puts(checksum_rsdp(rsdp) ? "PASS" : "FAIL");
+	vga_putc('\n');
+
+	vga_puts("oem id: ");
+	vga_putsn(rsdp->oemid, 6);
+	vga_putc('\n');
+
+	vga_puts("revision: ");
+	vga_putn(rsdp->revision);
+	vga_putc('\n');
+
+	vga_puts("addr: ");
+	vga_putx(rsdp->rsdt_address);
+	vga_putc('\n');
+}
+
+struct fadt *find_facp(struct xsdt *root_sdt) {
+	if (root_sdt == NULL)
+		return NULL;
+	size_t entries = (root_sdt->header.len - sizeof(root_sdt->header)) / 4;
+	for (size_t i = 0; i < entries; i++) {
+		struct acpi_sdt_header *header = (struct acpi_sdt_header *) root_sdt->sdt_pointers[i];
+		if (memcmp(header->signature, "FACP", 4) == 0 && checksum_sdt(header)) {
+			return (struct fadt *) header;
+		}
+	}
+	return NULL;
+}
+
+struct xsdp *find_rsdp() {
+	struct xsdp *rsdp = NULL;
+
+	char *ebda = (char*)((uintptr_t) *(uint16_t *)0x40e << 4);
+	for (char *ptr = ebda; ptr < ebda + 128; ptr += 16) {
+		if (memcmp(ptr, "RSD PTR ", 8) == 0 && checksum_xsdp((struct xsdp*) ptr)) {
+			rsdp = (struct xsdp *) ptr;
+		}
+	}
+
+	for (char *ptr = (char*)0x000E0000; ptr < (char*)0x000FFFFF; ptr += 16) {
+		if (memcmp(ptr, "RSD PTR ", 8) == 0 && checksum_xsdp((struct xsdp*) ptr)) {
+			if (rsdp == NULL)
+				rsdp = (struct xsdp *) ptr;
+		}
+	}
+	//print_rsdp(rsdp);
+	return rsdp;
+}
-- 
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