Merge remote branch 'erwan/master_new'

[profile/ivi/syslinux.git] / dos / crt0.S

diff --git a/dos/crt0.S b/dos/crt0.S
index 530059c..3be5712 100644 (file)
--- a/dos/crt0.S
+++ b/dos/crt0.S
@@ -1,71 +1,70 @@
        .code16
 
-       .section ".init","ax"
+#ifndef REGPARM
+# error "This file assumes -mregparm=3 -DREGPARM=3"
+#endif
+
+       .section ".text","ax"
        .globl _start
        .type _start,@function
 _start:
+       # Align the stack and make sure the high half is zero
+       andl $0xfff8,%esp
+
+       # DS, ES points to the PSP at this point
+       pushw %es               # Save PSP pointer
+       movw %cs,%ax
+       movw %ax,%ds
+       movw %ax,%es
+
        # Clear the .bss
        cld
        xorl %eax,%eax
        movw $__bss_start,%di
-       movw $_end+3,%cx
+       movw $__bss_end+3,%cx
        subw %di,%cx
        shrw $2,%cx
        rep ; stosl
 
-       # Compute argc and argv
-       movzbw 0x80,%cx
-       movl $0x81,%esi
-       movw $argv,%di
-
-       xorl %eax,%eax          # Dummy argv[0]
-       stosl
-
-1:
-       # Skip any space or control character
-       jcxz 2f
-       lodsb
-       decw %cx
-       cmp $0x20,%al
-       ja 3f
-5:
-       movb $0,-1(%si)
-       jmp 1b
+       # Copy the command line into our own segment
+       popw %fs                # FS -> PSP
+       movw $_cmdline,%di
+       movzbw %fs:0x80,%cx
+       movw $0x81,%si
+       fs ; rep ; movsb
+       # Already zero-terminated since we're writing into clean bss
 
-3:
-       movl %esi,%eax
-       stosl
-4:
-       # Skip this word
-       jcxz 2f
-       lodsb
-       decw %cx
-       cmp $0x20,%al
-       ja 4b
-       jmp 5b
-2:
-       xorl %eax,%eax          # Final null argv entry
-       stosl   
+       # Compute argc and argv (assumes REGPARM)
+       movl $_cmdline,%edx
+       pushl %eax              # Make space for argv
+       movl %esp,%eax
+       calll __parse_argv
+       pushl %eax              # argc
 
        # Initialize malloc
        calll __init_memory_arena
 
-       # Now call main...
-       pushl $argv             # Push argv
-       pushl %eax              # Dummy argc (we dont look at it)
+       # Now call main... (NOTE: gcc forces main to be regparm 0)
+       popl %eax               # argc
+       popl %edx               # argv
        calll main
-       pushl %eax
-       calll exit
-       hlt
+
+       # Here %eax is the exit code, fall through into exit
+
        .size _start,.-_start
 
        .globl exit
        .type exit,@function
 exit:
-       movb 4(%esp),%al
+       # Exit code already in %eax
        movb $0x4c,%ah          # Terminate program
        int $0x21
+1:     hlt
+       jmp 1b
        .size exit,.-exit
-       
+
        .section ".bss","aw"
-argv:  .space 4*128
+       .balign 4
+_cmdline:
+       .space 128
+       .size _cmdline,.-_cmdline