1 files changed, 63 insertions, 3 deletions
diff --git a/src/boot/mod_mem_map.c b/src/boot/mod_mem_map.c
index 701a12e..aee2cc9 100644
--- a/src/boot/mod_mem_map.c
+++ b/src/boot/mod_mem_map.c
@@ -4,8 +4,68 @@
 
 __asm__(".code16gcc\n");
 
+struct bios_address_descriptor {
+  uint32_t base_addr_low;
+  uint32_t base_addr_high;
+  uint32_t length_low;
+  uint32_t length_high;
+  uint32_t type;
+};
+
+uint32_t bios_mem_map_range(uint32_t continuation);
+void show_bios_mem_descriptor(struct bios_address_descriptor descriptor);
+
+static struct bios_address_descriptor curr_address_descriptor;
+
 void populate_memory_map(void) {
-  vga_graphics_write_str("pretend i populated the memory map, ok?");
-  vga_graphics_write_str("           system_memory_map = ");
-  vga_graphics_byte_hex(0x10);
+  vga_graphics_newln();
+  vga_graphics_return();
+  vga_graphics_write_str("system_memory_map = ");
+  vga_graphics_newln();
+  vga_graphics_return();
+  uint32_t cont = 0;
+  do {
+    cont = bios_mem_map_range(cont);
+    //vga_graphics_int_hex(cont);
+    show_bios_mem_descriptor(curr_address_descriptor);
+  } while (cont != 0);
+}
+
+
+void show_bios_mem_descriptor(struct bios_address_descriptor descriptor) {
+  vga_graphics_write_str("descriptor: ");
+  vga_graphics_write_str(" base: 0x");
+  vga_graphics_int_hex(descriptor.base_addr_high);
+  vga_graphics_int_hex(descriptor.base_addr_low);
+  vga_graphics_write_str(" length: 0x");
+  vga_graphics_int_hex(descriptor.length_high);
+  vga_graphics_int_hex(descriptor.length_low);
+  vga_graphics_write_str(" ");
+  vga_graphics_int_hex(descriptor.type);
+  vga_graphics_return();
+  vga_graphics_newln();
+}
+
+uint32_t bios_mem_map_range(uint32_t continuation) {
+// I know I really want the bottom 16 bits of this address. So no warning, thanks.
+#pragma GCC diagnostic ignored "-Wpointer-to-int-cast"
+  uint16_t address_descriptor = (uint16_t)(&curr_address_descriptor);
+#pragma GCC diagnostic pop
+  __asm__(
+    "push %%es                    \n"
+    "mov %0, %%ebx                \n"
+    "mov $0xE820, %%eax           \n"
+    "mov %1, %%di                 \n"
+    "mov $0, %%cx                 \n"
+    "mov %%cx, %%es               \n"
+    "mov $0x14, %%ecx             \n"
+    "mov $0x534d4150, %%edx       \n"
+    "int $0x15                    \n"
+    "mov %%ebx, %0                \n"
+    "pop %%es                     \n"
+    :"+r"(continuation)
+    :"r"(address_descriptor)
+    : "%eax", "%ebx", "%ecx", "%edx", "cc"
+  );
+  return continuation;
 }