From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:39545) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1W8uhU-0003mz-Du for qemu-devel@nongnu.org; Thu, 30 Jan 2014 11:42:56 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1W8uhM-0001gk-0I for qemu-devel@nongnu.org; Thu, 30 Jan 2014 11:42:48 -0500 Received: from mail-qc0-x22d.google.com ([2607:f8b0:400d:c01::22d]:51377) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1W8uhL-0001gg-RJ for qemu-devel@nongnu.org; Thu, 30 Jan 2014 11:42:39 -0500 Received: by mail-qc0-f173.google.com with SMTP id i8so5313092qcq.32 for ; Thu, 30 Jan 2014 08:42:39 -0800 (PST) Sender: Paolo Bonzini From: Paolo Bonzini Date: Thu, 30 Jan 2014 17:42:25 +0100 Message-Id: <1391100145-25369-1-git-send-email-pbonzini@redhat.com> In-Reply-To: <1391087394-17914-1-git-send-email-pbonzini@redhat.com> References: <1391087394-17914-1-git-send-email-pbonzini@redhat.com> Subject: [Qemu-devel] [PATCH 13/12] qapi: refine human printing of sizes List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: afaerber@redhat.com, armbru@redhat.com This fixes several bugs or shortcomings of the previous pretty-printer. In particular: * use PRIu64 instead of casting to long long * the exact value is included too * the correct unit of measure (MiB, GiB, etc.) is used. PiB and EiB are added too. * due to an off-by-one error, 512*2^30 was printed as 0.500MiB rather than 512MiB. floor(log2(val)) is equal to 63 - clz(val), while the code used 64. * The desired specification is %g rather than %f, which always uses three decimals in the current code. However %g would switch to scientific notation when the integer part is >= 1000 (e.g. 1000*2^30). To keep the code simple, switch to the higher power when the integer part is >= 1000; overflow is avoided by using frexp instead of clz. Suggested-by: Eric Blake Signed-off-by: Paolo Bonzini --- qapi/string-output-visitor.c | 23 ++++++++++++----------- 1 file changed, 12 insertions(+), 11 deletions(-) diff --git a/qapi/string-output-visitor.c b/qapi/string-output-visitor.c index 67a8798..95dd8fa 100644 --- a/qapi/string-output-visitor.c +++ b/qapi/string-output-visitor.c @@ -15,6 +15,7 @@ #include "qapi/visitor-impl.h" #include "qapi/qmp/qerror.h" #include "qemu/host-utils.h" +#include struct StringOutputVisitor { @@ -47,30 +48,30 @@ static void print_type_size(Visitor *v, uint64_t *obj, const char *name, Error **errp) { StringOutputVisitor *sov = DO_UPCAST(StringOutputVisitor, visitor, v); - static const char suffixes[] = { 'B', 'K', 'M', 'G', 'T' }; + static const char suffixes[] = { 'B', 'K', 'M', 'G', 'T', 'P', 'E' }; uint64_t div, val; char *out; int i; if (!sov->human) { - out = g_strdup_printf("%llu", (long long) *obj); + out = g_strdup_printf("%"PRIu64, *obj); string_output_set(sov, out); return; } val = *obj; - /* Compute floor(log2(val)). */ - i = 64 - clz64(val); - - /* Find the power of 1024 that we'll display as the units. */ - i /= 10; - if (i >= ARRAY_SIZE(suffixes)) { - i = ARRAY_SIZE(suffixes) - 1; - } + /* The exponent (returned in i) minus one gives us + * floor(log2(val * 1024 / 1000). The correction makes us + * switch to the higher power when the integer part is >= 1000. + */ + frexp(val / (1000.0 / 1024.0), &i); + i = (i - 1) / 10; + assert(i < ARRAY_SIZE(suffixes)); div = 1ULL << (i * 10); - out = g_strdup_printf("%0.03f%c", (double)val/div, suffixes[i]); + out = g_strdup_printf("%"PRIu64" (%0.3g %c%s)", val, + (double)val/div, suffixes[i], i ? "iB" : ""); string_output_set(sov, out); } -- 1.8.4.2