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Re: [Qemu-devel] [PATCH v7 14/23] hw/acpi/aml-build: Add ToUUID macro


From: Michael S. Tsirkin
Subject: Re: [Qemu-devel] [PATCH v7 14/23] hw/acpi/aml-build: Add ToUUID macro
Date: Tue, 19 May 2015 10:37:30 +0200

On Tue, May 19, 2015 at 08:41:39AM +0800, Shannon Zhao wrote:
> 
> 
> On 2015/5/19 0:17, Michael S. Tsirkin wrote:
> > On Thu, May 14, 2015 at 05:19:33PM +0800, Shannon Zhao wrote:
> >> > From: Shannon Zhao <address@hidden>
> >> > 
> >> > Add ToUUID macro, this is useful for generating PCIe ACPI table.
> >> > 
> >> > Signed-off-by: Shannon Zhao <address@hidden>
> >> > Signed-off-by: Shannon Zhao <address@hidden>
> >> > ---
> >> >  hw/acpi/aml-build.c         | 46 
> >> > +++++++++++++++++++++++++++++++++++++++++++++
> >> >  include/hw/acpi/aml-build.h |  1 +
> >> >  2 files changed, 47 insertions(+)
> >> > 
> >> > diff --git a/hw/acpi/aml-build.c b/hw/acpi/aml-build.c
> >> > index 6197896..0e4d35f 100644
> >> > --- a/hw/acpi/aml-build.c
> >> > +++ b/hw/acpi/aml-build.c
> >> > @@ -956,6 +956,52 @@ Aml *aml_qword_memory(AmlDecode dec, AmlMinFixed 
> >> > min_fixed,
> >> >                               addr_trans, len, flags);
> >> >  }
> >> >  
> >> > +static uint8_t Hex2Byte(const char *src)
> >> > +{
> >> > +    int hi = Hex2Digit(*src++);
> >> > +    int lo = Hex2Digit(*src);
> > 
> > Just src[0] src[1] would be clearer.
> > 
> >> > +
> >> > +    g_assert(((hi >= 0) && (hi <= 15)) && ((lo >= 0) && (lo <= 15)));
> > Pls use simple assert everywhere, it does not matter
> > and rest of acpi uses plain assert.
> > 
> >> > +    return (hi << 4) | lo;
> >> > +}
> > Really should be lower-case. We need to fix Hex2Digit too,
> > but since Hex2Digit is broken, I'll let this one in
> > and we can fix both with a patch on top.
> > 
> >> > +
> >> > +/*
> >> > + * ACPI 3.0: 17.5.124 ToUUID (Convert String to UUID Macro)
> >> > + * e.g. UUID: aabbccdd-eeff-gghh-iijj-kkllmmnnoopp
> >> > + * call aml_touuid("aabbccdd-eeff-gghh-iijj-kkllmmnnoopp");
> >> > + */
> >> > +Aml *aml_touuid(const char *uuid)
> >> > +{
> >> > +    Aml *var = aml_bundle(0x11 /* BufferOp */, AML_BUFFER);
> >> > +
> >> > +    /* format: aabbccdd-eeff-gghh-iijj-kkllmmnnoopp */
> > This documents the argument, so really belongs near the
> > function's head.
> > 
> >> > +    g_assert((strlen(uuid) == 36) && (uuid[8] == '-') && (uuid[13] == 
> >> > '-')
> >> > +              && (uuid[18] == '-') && (uuid[23] == '-'));
> > Does something else validate the parameter?
> > It's not friendly to handle errors by assert.
> > Why doesn't that something else give us a pre-parse structure then?
> > 
> 
> a pre-parse structure?

Yes - have caller validate and parse the string, on failure report
it to user cleanly, on success give us a byte array
avoiding need to call Hex2Byte.


> > 
> >> > +
> >> > +    build_append_byte(var->buf, Hex2Byte(uuid + 6)); /* dd - at offset 
> >> > 00 */
> >> > +    build_append_byte(var->buf, Hex2Byte(uuid + 4)); /* cc - at offset 
> >> > 01 */
> >> > +    build_append_byte(var->buf, Hex2Byte(uuid + 2)); /* bb - at offset 
> >> > 02 */
> >> > +    build_append_byte(var->buf, Hex2Byte(uuid + 0)); /* aa - at offset 
> >> > 03 */
> >> > +
> >> > +    build_append_byte(var->buf, Hex2Byte(uuid + 11)); /* ff - at offset 
> >> > 04 */
> >> > +    build_append_byte(var->buf, Hex2Byte(uuid + 9)); /* ee - at offset 
> >> > 05 */
> >> > +
> >> > +    build_append_byte(var->buf, Hex2Byte(uuid + 16)); /* hh - at offset 
> >> > 06 */
> >> > +    build_append_byte(var->buf, Hex2Byte(uuid + 14)); /* gg - at offset 
> >> > 07 */
> >> > +
> >> > +    build_append_byte(var->buf, Hex2Byte(uuid + 19)); /* ii - at offset 
> >> > 08 */
> >> > +    build_append_byte(var->buf, Hex2Byte(uuid + 21)); /* jj - at offset 
> >> > 09 */
> >> > +
> >> > +    build_append_byte(var->buf, Hex2Byte(uuid + 24)); /* kk - at offset 
> >> > 10 */
> >> > +    build_append_byte(var->buf, Hex2Byte(uuid + 26)); /* ll - at offset 
> >> > 11 */
> >> > +    build_append_byte(var->buf, Hex2Byte(uuid + 28)); /* mm - at offset 
> >> > 12 */
> >> > +    build_append_byte(var->buf, Hex2Byte(uuid + 30)); /* nn - at offset 
> >> > 13 */
> >> > +    build_append_byte(var->buf, Hex2Byte(uuid + 32)); /* oo - at offset 
> >> > 14 */
> >> > +    build_append_byte(var->buf, Hex2Byte(uuid + 34)); /* pp - at offset 
> >> > 15 */
> > Can we use strtoull?
> > 
> 
> Igor and I have a discussion on this. I used strtol before and we got an
> agreement on current approach.
> 
> -- 
> Shannon



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