[syslinux] [Syslinux-GSoC] Exporting real-mode functions

[H. Peter Anvin]

liu Aleaxander wrote:
> 
> then in the cache.c
> void getoneblk(char *buf, __u32 block, int block_size)
> {
>         int sec_per_block = block_size / 512; /* 512==sector size */
>         uint16_t fun_seg, fun_off;
>         com32sys_t regs;
>        
>         //extern void (*getlinsec) ();
> 
>         regs.eax.l = block * sec_per_block;
>         regs.ebp.l = sec_per_block;
>         regs.es <http://regs.es> = SEG(buf);
>         regs.ebx.w[0] = OFFS(buf);
> 
>         fun_seg = SEG(getlinsec);
>         fun_off = OFFS(getlinsec);
>        
>         __farcall(fun_seg, fun_off, &regs, NULL);
> }
> 
> it says getlinsec not defined.
> 

Ah.

On the C side, you want to do this:

void getlinsec(void);		/* Prototype */


/* ... */
	__farcall(0, (size_t)getlinsec, &regs, NULL);


This is really hideously ugly in terms of syntax, so I just checked in a
wrapper called call16():

	call16(getlinsec, &regs, NULL);

You still need the prototype as shown.  It really should be put into
core.h or another header file.

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.