From: Michael Snyder <msnyder@redhat.com>
To: Kazu Hirata <kazu@cs.umass.edu>
Cc: gdb-patches@sources.redhat.com, dvenkat@noida.hcltech.com,
avolkov@transas.com
Subject: Re: [PATCH/RFA] h8300 sim: add daa and das insns
Date: Sun, 13 Apr 2003 16:57:00 -0000 [thread overview]
Message-ID: <3E9996FB.58B22C50@redhat.com> (raw)
In-Reply-To: <20030412.172441.63131380.kazu@cs.umass.edu>
Kazu Hirata wrote:
>
> Hi Michael,
>
> > Here's my implementation of daa/das:
>
> + if (!c && (0 <= (res >> 4) && (res >> 4) <= 9) &&
> + !h && (0 <= (res & 0xf) && (res & 0xf) <= 9))
>
> The GNU coding standard says
>
> if (A
> && B)
Ugh. I hate it, but OK. My way scans so much better...
> so we would have to fix formatting.
>
> + else if ( c && (1 <= (res >> 4) && (res >> 4) <= 2) &&
> + !h && (0 <= (res & 0xf) && (res & 0xf) <= 9))
> + res = res + 0x60; /* Value added == 60. */
> + else if ( c && (1 <= (res >> 4) && (res >> 4) <= 2) &&
> + !h && (10 <= (res & 0xf) && (res & 0xf) <= 15))
> + res = res + 0x66; /* Value added == 66. */
> + else if (c && (1 <= (res >> 4) && (res >> 4) <= 3) &&
> + h && (0 <= (res & 0xf) && (res & 0xf) <= 3))
> + res = res + 0x66; /* Value added == 66. */
>
> IMHO, for the last three cases of DAA, the carry flag won't be set to
> 1 because adding 0x66 does not generate a carry. We can put a hack
> like "res |= 0x100;" after "res += 0x66;" or replace "res += 0x66;"
> with "res += 0x166;" so that "alu8:" can take care of this, but I
> don't know how much you like these. :-)
Right you are. I think your suggestion is both necessary and sufficient.
Sure it's odd, but this is binary coded decimal we're talking about...
I'll check it in with your suggestions. Thanks.
prev parent reply other threads:[~2003-04-13 16:57 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-04-08 6:24 Michael Snyder
2003-04-12 21:25 ` Kazu Hirata
2003-04-13 16:57 ` Michael Snyder [this message]
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