Add protocol header for C code

include/protocol.h

@@ -0,0 +1,63 @@
+#pragma once
+// CPU state when entering kernel:
+// Virtual memory: lower 1GiB identity mapped
+// Selectors are flat
+// TODO: CR0? (spec. if NX, PAE, PSE are enabled)
+// From UEFI specification:
+//  * CR0.EM = 0
+//  * CR0.TS = 0
+// Stack:
+//  * At least 120KiB available
+// FPU state:
+//  * CW = 0x037F
+// MMX state:
+//  * CW = 0x1F80
+// Interrupts are disabled
+
+#define YB_KERNEL_MAGIC_V1          0xA197A9B007B007UL
+#define YB_LOADER_MAGIC_V1          0x700B700B9A791AUL
+
+#define YB_CMDLINE_SIZE             256
+
+#define YB_VIDEO_FORMAT_RGB32       0
+#define YB_VIDEO_FORMAT_BGR32       1
+
+#if !defined(__ASM__)
+#include <stdint.h>
+
+struct yboot_header {
+    uint64_t kernel_magic;
+    uint64_t loader_magic;
+};
+
+struct yboot_v1 {
+    struct yboot_header header;
+
+    uint64_t memory_map_data;                   // R
+    uint32_t memory_map_size;                   // RW
+    uint32_t memory_map_entsize;                // W
+
+    // Video mode settings
+    uint32_t video_width;                       // RW
+    uint32_t video_height;                      // RW
+    uint32_t video_format;                      // RW
+    uint32_t __pad0;                            // --
+    uint64_t video_framebuffer;                 // W
+    uint64_t video_pitch;                       // W
+
+    uint64_t elf_symtab_hdr;                    // W
+    uint64_t elf_symtab_data;                   // W
+    uint64_t elf_strtab_hdr;                    // W
+    uint64_t elf_strtab_data;                   // W
+
+    uint64_t initrd_base;                       // W
+    uint64_t initrd_size;                       // W
+
+    uint64_t rsdp;                              // W
+
+    char cmdline[YB_CMDLINE_SIZE];              // W
+};
+#endif
+
+// * W - fields written by this loader
+// * R - fields with kernel-specified values