Re: [Qemu-devel] OPT_SIZE parsing

[Ian Molton <ian.molton@collabora.co.uk>]

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Paul Brook wrote:
> On Tuesday 17 November 2009, Ian Molton wrote:

> When do we ever have a value that can be specified as both bits and bytes? I 
> don't think it makes sense to specify this. The fact that we accept a "b" 
> suffix at all is suspicious.

Well, entropy is often measured in 'bits' and I'd like to be able to
specify the entropy rate limit in bits/s or kbits/s when I submit the
virtio-rng driver.

> For the magnitude IMO only sane thing to do is ignore the case, and decide 
> whether we're using binary or decimal multipliers. Remember that if you're 
> being pedantic then "m" should be 0.001.

Quite. I'm happy with binary multipliers, personally.

I've cooked up this patch (attached) to add a SIZE property to qdevs.
I've kept the same semantics as the OPT_SIZE parser for now.

TIA for the review.

-Ian


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>From 64dc4afcc0a6ba0559e918ff75229133b8887eee Mon Sep 17 00:00:00 2001
From: Ian Molton <ian.molton@collabora.co.uk>
Date: Tue, 17 Nov 2009 14:10:10 +0000
Subject: [PATCH] Add SIZE type to qdev properties

    	This patch adds a 'SIZE' type property to those available to qdevs.
    It is the analogue of the OPT_SIZE property for options.

    Signed-off-by: Ian Molton <ian.molton@collabora.co.uk>
---
 hw/qdev-properties.c |   59 ++++++++++++++++++++++++++++++++++++++++++++++++++
 hw/qdev.h            |    4 +++
 2 files changed, 63 insertions(+), 0 deletions(-)

diff --git a/hw/qdev-properties.c b/hw/qdev-properties.c
index bda6699..4899c27 100644
--- a/hw/qdev-properties.c
+++ b/hw/qdev-properties.c
@@ -194,6 +194,65 @@ PropertyInfo qdev_prop_hex64 = {
     .print = print_hex64,
 };
 
+/* --- 64bit unsigned int 'size' type --- */
+
+static int parse_size(DeviceState *dev, Property *prop, const char *str)
+{
+    uint64_t *ptr = qdev_get_prop_ptr(dev, prop);
+    char *postfix;
+    double sizef;
+
+    if (str != NULL) {
+        sizef = strtod(str, &postfix);
+        switch (*postfix) {
+        case 'T':
+            sizef *= 1024;
+        case 'G':
+            sizef *= 1024;
+        case 'M':
+            sizef *= 1024;
+        case 'K':
+        case 'k':
+            sizef *= 1024;
+        case 'b':
+        case '\0':
+            *ptr = (uint64_t) sizef;
+            break;
+        default:
+            fprintf(stderr, "Option '%s' needs size as parameter\n", prop->name);
+            fprintf(stderr, "You may use k, M, G or T suffixes for "
+                    "kilobytes, megabytes, gigabytes and terabytes.\n");
+            return -1;
+        }
+    } else {
+        fprintf(stderr, "Option '%s' needs a parameter\n", prop->name);
+        return -1;
+    }
+
+    return 0;
+}
+
+static int print_size(DeviceState *dev, Property *prop, char *dest, size_t len)
+{
+    uint64_t *ptr = qdev_get_prop_ptr(dev, prop);
+    char suffixes[] = {'T', 'G', 'M', 'K', 'B'};
+    int i;
+    uint64_t div;
+
+    for(div = (long int)1 << 40 ;
+        !(*ptr / div) ; div >>= 10, i++);
+
+    return snprintf(dest, len, "%0.03f%c", (double)*ptr/div, suffixes[i]);
+}
+
+PropertyInfo qdev_prop_size = {
+    .name  = "size",
+    .type  = PROP_TYPE_SIZE,
+    .size  = sizeof(uint64_t),
+    .parse = parse_size,
+    .print = print_size,
+};
+
 /* --- string --- */
 
 static int parse_string(DeviceState *dev, Property *prop, const char *str)
diff --git a/hw/qdev.h b/hw/qdev.h
index 41642ee..5521093 100644
--- a/hw/qdev.h
+++ b/hw/qdev.h
@@ -74,6 +74,7 @@ enum PropertyType {
     PROP_TYPE_UINT32,
     PROP_TYPE_INT32,
     PROP_TYPE_UINT64,
+    PROP_TYPE_SIZE,
     PROP_TYPE_TADDR,
     PROP_TYPE_MACADDR,
     PROP_TYPE_DRIVE,
@@ -189,6 +190,7 @@ extern PropertyInfo qdev_prop_int32;
 extern PropertyInfo qdev_prop_uint64;
 extern PropertyInfo qdev_prop_hex32;
 extern PropertyInfo qdev_prop_hex64;
+extern PropertyInfo qdev_prop_size;
 extern PropertyInfo qdev_prop_string;
 extern PropertyInfo qdev_prop_chr;
 extern PropertyInfo qdev_prop_ptr;
@@ -226,6 +228,8 @@ extern PropertyInfo qdev_prop_pci_devfn;
     DEFINE_PROP_DEFAULT(_n, _s, _f, _d, qdev_prop_hex32, uint32_t)
 #define DEFINE_PROP_HEX64(_n, _s, _f, _d)                       \
     DEFINE_PROP_DEFAULT(_n, _s, _f, _d, qdev_prop_hex64, uint64_t)
+#define DEFINE_PROP_SIZE(_n, _s, _f, _d)                       \
+    DEFINE_PROP_DEFAULT(_n, _s, _f, _d, qdev_prop_size, uint64_t)
 #define DEFINE_PROP_PCI_DEVFN(_n, _s, _f, _d)                   \
     DEFINE_PROP_DEFAULT(_n, _s, _f, _d, qdev_prop_pci_devfn, uint32_t)
 
-- 
1.6.5