From: Paul Eggert <eggert@cs.ucla.edu>
To: Stefan Monnier <monnier@IRO.UMontreal.CA>
Cc: Dmitry Antipov <antipov@mvista.com>, emacs-devel@gnu.org
Subject: Re: immediate strings #2
Date: Mon, 28 Nov 2011 14:18:04 -0800 [thread overview]
Message-ID: <4ED4089C.3050203@cs.ucla.edu> (raw)
In-Reply-To: <jwvborwcgee.fsf-monnier+emacs@gnu.org>
On 11/28/11 09:33, Stefan Monnier wrote:
> You need to move the immbit and gcmarkbit
> into the union :-(
Yes, something like this perhaps? It also adds a bit of checking for
underlying assumptions about word size.
#include <verify.h>
#define IMMEDIATE_STRING_LENGTH_BITS 7
struct Data_Lisp_String
{
unsigned int immediate_bit : 1;
signed int : IMMEDIATE_STRING_LENGTH_BITS; /* padding for immediate size */
unsigned int gcmarkbit : 1;
signed int : IMMEDIATE_STRING_LENGTH_BITS; /* and for immediate size_byte */
INTERVAL intervals;
ptrdiff_t size;
ptrdiff_t size_byte;
unsigned char *data;
};
#define IMMEDIATE_STRING_SIZE \
(sizeof (struct Data_Lisp_String) - offsetof (struct Data_Lisp_String, size))
verify (IMMEDIATE_STRING_SIZE <= 1 << (IMMEDIATE_STRING_LENGTH_BITS - 1));
struct Immediate_Lisp_String
{
unsigned int immediate_bit : 1;
signed int size : IMMEDIATE_STRING_LENGTH_BITS;
unsigned int gcmarkbit : 1;
signed int size_byte : IMMEDIATE_STRING_LENGTH_BITS;
INTERVAL intervals;
unsigned char data[IMMEDIATE_STRING_SIZE];
};
union Lisp_String
{
/* When IMMEDIATE.IMMEDIATE_BIT is 0. */
struct Data_Lisp_String data;
/* When IMMEDIATE.IMMEDIATE_BIT is 1. */
struct Immediate_Lisp_String immediate;
};
next prev parent reply other threads:[~2011-11-28 22:18 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-28 9:11 immediate strings #2 Dmitry Antipov
2011-11-28 17:33 ` Stefan Monnier
2011-11-28 19:48 ` Ken Raeburn
2011-11-28 20:10 ` Andreas Schwab
2011-11-28 21:54 ` Stefan Monnier
2011-11-28 22:25 ` Andreas Schwab
2011-11-29 0:57 ` Ken Raeburn
2011-11-29 8:44 ` Andreas Schwab
2011-11-29 15:48 ` Ken Raeburn
2011-11-29 16:08 ` Andreas Schwab
2011-11-30 16:43 ` Ken Raeburn
2011-11-28 22:18 ` Paul Eggert [this message]
2011-11-29 2:07 ` Stefan Monnier
2011-11-29 3:37 ` Dmitry Antipov
2011-11-29 8:50 ` Paul Eggert
2011-11-30 5:37 ` Dmitry Antipov
2011-11-30 9:35 ` Paul Eggert
2011-11-30 16:43 ` Ken Raeburn
2011-11-30 21:44 ` Paul Eggert
2011-11-29 3:17 ` Dmitry Antipov
2011-11-29 5:29 ` Dmitry Antipov
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