Implement fmt_human_2() and fmt_human_10()

These functions take the raw number and a unit and automatically
print it out "scaled down" to a proper SI-prefix, for powers of 2
and 10 respectively.

Apply them to the 2-power cases and keep the 10-power for a later
commit.

6 files changed, 61 insertions, 32 deletions

diff --git a/components/disk.c b/components/disk.c
index db18d12..998ad47 100644
--- a/components/disk.c
+++ b/components/disk.c
@@ -16,7 +16,7 @@ disk_free(const char *mnt)
 		return NULL;
 	}
 
-	return fmt_scaled(fs.f_frsize * fs.f_bavail);
+	return fmt_human_2(fs.f_frsize * fs.f_bavail, "B");
 }
 
 const char *
@@ -43,7 +43,7 @@ disk_total(const char *mnt)
 		return NULL;
 	}
 
-	return fmt_scaled(fs.f_frsize * fs.f_blocks);
+	return fmt_human_2(fs.f_frsize * fs.f_blocks, "B");
 }
 
 const char *
@@ -56,5 +56,5 @@ disk_used(const char *mnt)
 		return NULL;
 	}
 
-	return fmt_scaled(fs.f_frsize * (fs.f_blocks - fs.f_bfree));
+	return fmt_human_2(fs.f_frsize * (fs.f_blocks - fs.f_bfree), "B");
 }
diff --git a/components/netspeeds.c b/components/netspeeds.c
index 32e78d6..f0f7455 100644
--- a/components/netspeeds.c
+++ b/components/netspeeds.c
@@ -25,9 +25,12 @@
 		if (pscanf(path, "%llu", &rxbytes) != 1) {
 			return NULL;
 		}
+		if (oldrxbytes == 0) {
+			return NULL;
+		}
 
-		return oldrxbytes ? fmt_scaled((rxbytes - oldrxbytes) *
-		                               1000 / interval) : NULL;
+		return fmt_human_2((rxbytes - oldrxbytes) *
+		                   1000 / interval, "B/s");
 	}
 
 	const char *
@@ -48,9 +51,12 @@
 		if (pscanf(path, "%llu", &txbytes) != 1) {
 			return NULL;
 		}
+		if (oldtxbytes == 0) {
+			return NULL;
+		}
 
-		return oldtxbytes ? fmt_scaled((txbytes - oldtxbytes) *
-		                               1000 / interval) : NULL;
+		return fmt_human_2((txbytes - oldtxbytes) *
+		                   1000 / interval, "B/s");
 	}
 #elif defined(__OpenBSD__)
 	#include <string.h>
@@ -87,9 +93,12 @@
 			warn("reading 'if_data' failed");
 			return NULL;
 		}
+		if (oldrxbytes == 0) {
+			return NULL;
+		}
 
-		return oldrxbytes ? fmt_scaled((rxbytes - oldrxbytes) *
-		                               1000 / interval) : NULL;
+		return fmt_human_2((rxbytes - oldrxbytes) *
+		                   1000 / interval, "B/s");
 	}
 
 	const char *
@@ -120,8 +129,11 @@
 			warn("reading 'if_data' failed");
 			return NULL;
 		}
+		if (oldtxbytes == 0) {
+			return NULL;
+		}
 
-		return oldtxbytes ? fmt_scaled((txbytes - oldtxbytes) *
-		                               1000 / interval) : NULL;
+		return fmt_human_2((txbytes - oldtxbytes) *
+		                   1000 / interval, "B/s");
 	}
 #endif
diff --git a/components/ram.c b/components/ram.c
index 0eb2ea9..1c12aab 100644
--- a/components/ram.c
+++ b/components/ram.c
@@ -14,7 +14,7 @@
 		               "MemFree: %ld kB\n"
 		               "MemAvailable: %ld kB\n",
 		               &free, &free, &free) == 3) ?
-		       fmt_scaled(free * 1024) : NULL;
+		       fmt_human_2(free * 1024, "B") : NULL;
 	}
 
 	const char *
@@ -39,7 +39,7 @@
 		long total;
 
 		return (pscanf("/proc/meminfo", "MemTotal: %ld kB\n", &total) == 1) ?
-		       fmt_scaled(total * 1024) : NULL;
+		       fmt_human_2(total * 1024, "B") : NULL;
 	}
 
 	const char *
@@ -53,7 +53,7 @@
 		               "MemAvailable: %ld kB\nBuffers: %ld kB\n"
 		               "Cached: %ld kB\n",
 		               &total, &free, &buffers, &buffers, &cached) == 5) ?
-		       fmt_scaled((total - free - buffers - cached) * 1024) : NULL;
+		       fmt_human_2((total - free - buffers - cached) * 1024, "B") : NULL;
 	}
 #elif defined(__OpenBSD__)
 	#include <stdlib.h>
@@ -83,7 +83,7 @@
 
 		if (load_uvmexp(&uvmexp)) {
 			free_pages = uvmexp.npages - uvmexp.active;
-			return fmt_scaled(pagetok(free_pages, uvmexp.pageshift) * 1024);
+			return fmt_human_2(pagetok(free_pages, uvmexp.pageshift) * 1024, "B");
 		}
 
 		return NULL;
@@ -109,7 +109,7 @@
 		struct uvmexp uvmexp;
 
 		if (load_uvmexp(&uvmexp)) {
-			return fmt_scaled(pagetok(uvmexp.npages, uvmexp.pageshift) * 1024);
+			return fmt_human_2(pagetok(uvmexp.npages, uvmexp.pageshift) * 1024, "B");
 		}
 
 		return NULL;
@@ -121,7 +121,7 @@
 		struct uvmexp uvmexp;
 
 		if (load_uvmexp(&uvmexp)) {
-			return fmt_scaled(pagetok(uvmexp.active, uvmexp.pageshift) * 1024);
+			return fmt_human_2(pagetok(uvmexp.active, uvmexp.pageshift) * 1024, "B");
 		}
 
 		return NULL;
diff --git a/components/swap.c b/components/swap.c
index 64feceb..c005691 100644
--- a/components/swap.c
+++ b/components/swap.c
@@ -48,7 +48,7 @@
 		}
 		sscanf(match, "SwapFree: %ld kB\n", &free);
 
-		return fmt_scaled(free * 1024);
+		return fmt_human_2(free * 1024, "B");
 	}
 
 	const char *
@@ -94,7 +94,7 @@
 		}
 		sscanf(match, "SwapTotal: %ld kB\n", &total);
 
-		return fmt_scaled(total * 1024);
+		return fmt_human_2(total * 1024, "B");
 	}
 
 	const char *
@@ -122,7 +122,7 @@
 		}
 		sscanf(match, "SwapFree: %ld kB\n", &free);
 
-		return fmt_scaled((total - free - cached) * 1024);
+		return fmt_human_2((total - free - cached) * 1024, "B");
 	}
 #elif defined(__OpenBSD__)
 	#include <stdlib.h>
@@ -174,7 +174,7 @@
 
 		getstats(&total, &used);
 
-		return fmt_scaled((total - used) * 1024);
+		return fmt_human_2((total - used) * 1024, "B");
 	}
 
 	const char *
@@ -194,7 +194,7 @@
 
 		getstats(&total, &used);
 
-		return fmt_scaled(total * 1024);
+		return fmt_human_2(total * 1024, "B");
 	}
 
 	const char *
@@ -204,6 +204,6 @@
 
 		getstats(&total, &used);
 
-		return fmt_scaled(used * 1024);
+		return fmt_human_2(used * 1024, "B");
 	}
 #endif
diff --git a/util.c b/util.c
index 923d4df..5936a6d 100644
--- a/util.c
+++ b/util.c
@@ -87,19 +87,35 @@ bprintf(const char *fmt, ...)
 }
 
 const char *
-fmt_scaled(size_t bytes)
+fmt_human_2(size_t num, char *unit)
 {
-	unsigned int i;
-	float scaled;
-	const char *units[] = { "B", "KiB", "MiB", "GiB", "TiB", "PiB", "EiB",
-	                        "ZiB", "YiB" };
+	size_t i;
+	double scaled;
+	const char *prefix[] = { "", "Ki", "Mi", "Gi", "Ti", "Pi", "Ei",
+	                         "Zi", "Yi" };
 
-	scaled = bytes;
-	for (i = 0; i < LEN(units) && scaled >= 1024; i++) {
+	scaled = num;
+	for (i = 0; i < LEN(prefix) && scaled >= 1024; i++) {
 		scaled /= 1024.0;
 	}
 
-	return bprintf("%.1f%s", scaled, units[i]);
+	return bprintf("%.1f%s%s", scaled, prefix[i], unit);
+}
+
+const char *
+fmt_human_10(size_t num, char *unit)
+{
+	size_t i;
+	double scaled;
+	const char *prefix[] = { "", "K", "M", "G", "T", "P", "E",
+	                         "Z", "Y" };
+
+	scaled = num;
+	for (i = 0; i < LEN(prefix) && scaled >= 1000; i++) {
+		scaled /= 1000.0;
+	}
+
+	return bprintf("%.1f%s%s", scaled, prefix[i], unit);
 }
 
 int
diff --git a/util.h b/util.h
index 5111b37..64e30d0 100644
--- a/util.h
+++ b/util.h
@@ -10,5 +10,6 @@ void die(const char *, ...);
 
 int esnprintf(char *str, size_t size, const char *fmt, ...);
 const char *bprintf(const char *fmt, ...);
-const char *fmt_scaled(size_t);
+const char *fmt_human_2(size_t num, char *unit);
+const char *fmt_human_10(size_t num, char *unit);
 int pscanf(const char *path, const char *fmt, ...);