Finding both the PXENV+ and !PXE structs

Makefile

@@ -3,6 +3,7 @@
 OBJS=\
      src/nbp.o \
      src/bios.o \
+     src/pxe.o \
      src/std.o \
      src/main.o \
      # end of object list

src/main.c

@@ -115,22 +115,58 @@ pg_setup()
 	return cr3;
 }
 
+struct PXENV {
+	uint8_t  signature[6];
+	uint16_t version;
+	uint8_t  length;
+	uint8_t  checksum;
+	uint32_t rmentry;
+	uint32_t pmoffset;
+};
+
+struct exPXE {
+	uint8_t  signature[4];
+	uint8_t  length;
+	uint8_t  checksum;
+	uint8_t  revision;
+	uint8_t  reserved;
+	uint32_t undiromid;
+	uint32_t bcromid;
+	uint32_t rmentry;
+	uint32_t pmentry;
+};
+
+//extern uint32_t pxe_call(uint16_t func, offset, segment);
+
+extern struct PXENV *PXENV;
+extern struct exPXE *exPXE;
+
 void
 main()
 {
-	//blank_screen(0x10);
-	//move_cursor(0, 0);
-	display_string(0x14, "Netboot via fernlader v2 ...\r\n");
+	blank_screen(0x10);
+	move_cursor(0, 0);
+	//display_string(0x14, "Netboot via fernlader v2 ...\r\n");
 	bios_write("Going well ...\r\n");
 
+	if (memcmp(PXENV->signature, "PXENV+", 6) != 0) {
+		bios_write("missing PXENV+ signature\r\n");
+	}
+	if (PXENV->version >= 0x0201) {
+		bios_write("!PXE version\r\n");
+		if (memcmp(exPXE->signature, "!PXE", 4) != 0) {
+			bios_write("missing !PXE signature\r\n");
+		}
+	}
+
 	memcpy(bootboot.magic, BOOTBOOT_MAGIC, sizeof bootboot.magic);
 	bootboot.size = 128;
 	bootboot.protocol = PROTOCOL_MINIMAL | LOADER_BIOS;
 	bootboot.numcores = 1;
 
-	display_string(0x0E, "init\r\n");
+	//display_string(0x0E, "init\r\n");
 	struct e820_entry *end = bios_getmap(memmap);
-	display_string(0x0E, "karlos\r\n");
+	//display_string(0x0E, "karlos\r\n");
 	for (int i = 0; ; i++) {
 		if (&memmap[i] >= end) break;
 		char buf[2];

src/nbp.S

@@ -9,20 +9,37 @@
             // _start: entry point
 _start:     cli
             cld
+
+            mov         %ss, %ax
+            mov         %ax, %cs:real_ss
+
+            xor         %eax, %eax
+            mov         %es, %ax
+            shl         $4, %eax
+            movzwl      %bx, %ebx
+            add         %eax, %ebx
+            mov         %ebx, %cs:PXENV
+
+            xor         %eax, %eax
+            xor         %ebx, %ebx
+            mov         %sp, %bx
+            mov         %ss:6(%bx), %ax
+            mov         %ss:4(%bx), %bx
+            shl         $4, %eax
+            add         %eax, %ebx
+            mov         %ebx, %cs:exPXE
+
             mov         %sp, %bp
             xor         %ax, %ax
             mov         %ax, %ds
             mov         %ax, %es
 
-            mov         %ss, %ax
-            mov         %ax, real_ss
-
             // initialize our own BSS section
             mov         $_bss_start, %di
             mov         $_bss_end, %cx
             sub         %di, %cx
             xor         %al, %al
-            rep         stosb
+            rep stosb
 
             // a20_enable: Allow use of 'high' (>1Mb) memory
 a20_enable: // Of all the ways to toggle A20, we only try the Fast A20 Gate.
@@ -45,6 +62,12 @@ prot_enter: lgdt        GDT_PTR
 
             .data
 
+            .global     PXENV
+PXENV:      .long       0
+
+            .global     exPXE
+exPXE:      .long       0
+
             .global     real_ss
 real_ss:    .word       0
 

src/pxe.S

@@ -0,0 +1,24 @@
+            // vim: ft=gas:et:sw=12:ts=12:sts=12
+
+            .include    "src/mode.S"
+
+            .data
+
+pxe_entry:  .word       0
+
+            .text
+            .global     pxe_call
+            .code32
+pxe_call:   push        %ebp
+            mov         %esp, %ebp
+
+            PROT16
+
+            call        (pxe_entry)
+            push        %eax
+
+            PROT32
+
+            pop         %eax
+            leave
+            ret

src/std.c

@@ -7,10 +7,21 @@ memcpy(void *dst, const void *src, size_t n)
 	__asm__ ("rep movsb"
 		: "+D"(di), "+S"(src), "+c"(n)
 		:
-		: "memory");
+		: "cc", "memory");
 	return dst;
 }
 
+int
+memcmp(const void *src1, const void *src2, size_t n)
+{
+	__asm__ ("repe cmpsb"
+		: "+D"(src2), "+S"(src1), "+c"(n)
+		:
+		: "cc", "memory");
+	if (n == 0) return 0;
+	return src1 < src2 ? -1 : 1;
+}
+
 size_t
 strlen(const char *s)
 {