From e41b509d68afb1f329c8558b6edfe2fcbac88e66 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Sat, 8 Feb 2014 11:01:57 +0100 Subject: qapi: Refine human printing of sizes MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Reviewed-by: Igor Mammedov Reviewed-by: Eric Blake Signed-off-by: Paolo Bonzini Signed-off-by: Andreas Färber --- qapi/string-output-visitor.c | 23 ++++++++++++----------- 1 file changed, 12 insertions(+), 11 deletions(-) (limited to 'qapi') diff --git a/qapi/string-output-visitor.c b/qapi/string-output-visitor.c index 67a8798292..fb1d2e806d 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); } -- cgit v1.2.3