Add Linux support, fix whitespace

Read /proc/meminfo, pull out some numbers and use them.

README.md

@@ -1,2 +1,11 @@
 # xmem(1) X11 Utility
 ![fvwm and xmem](https://git.sdf.org/bch/xmem/raw/branch/master/www/xmem_fvwmbar.png)
+
+# Compile
+
+```shell
+  # Linux with DEBUG:
+  CFLAGS=-DDEBUG make -f Makefile.linux
+  # BSD:
+  make
+```

get_mem.c

@@ -244,3 +244,106 @@ void GetMemLoadPoint(Widget w, caddr_t closure, caddr_t call_data)
 }
 
 #endif
+
+
+
+
+
+/* ------------------------------------------------------------------ */
+#if __gnu_linux__
+#include <X11/Xos.h>
+#include <X11/Intrinsic.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <err.h>
+#include "MemStripChart.h"
+
+static unsigned int total_mem = 0;
+
+int GetRamInKB(int type)
+{
+    FILE *meminfo = fopen("/proc/meminfo", "r");
+    if(meminfo == NULL)
+        err(1, "fopen on /proc/meminfo failed: ");
+
+    char line[256];
+    int memory = -1;
+    int found = 0;
+    while(found == 0 && fgets(line, sizeof(line), meminfo))
+    {
+        if (type == 1) {
+            if((sscanf(line, "MemTotal: %d kB", &memory)) == 1)
+                found = 1;
+        }
+        if (type == 2) {
+            if(sscanf(line, "MemFree: %d kB", &memory) == 1)
+                found = 1;
+        }
+        if (type == 3) {
+            if(sscanf(line, "Buffers: %d kB", &memory) == 1)
+                found = 1;
+        }
+        if (type == 4) {
+            if(sscanf(line, "Cached: %d kB", &memory) == 1)
+                found = 1;
+        }
+        if (type == 5) {
+            if(sscanf(line, "SwapTotal: %d kB", &memory) == 1)
+                found = 1;
+        }
+        if (type == 6) {
+            if(sscanf(line, "SwapFree: %d kB", &memory) == 1)
+                found = 1;
+        }
+    }
+    if (!found)
+        warnx("failed to sscanf type %d", type);
+    fclose(meminfo);
+    return memory;
+}
+
+static void init_total_mem(void)
+{
+    if (total_mem <= 0)
+        total_mem = GetRamInKB(1);
+#ifdef DEBUG
+    printf("MemTotal: %d\n", total_mem);
+#endif
+}
+
+
+void GetMemLoadPoint(Widget w, caddr_t closure, caddr_t call_data)
+{
+        MemStripChartCallbackData ret;
+
+        init_total_mem();
+        /* free(1):
+         *   total
+         *   used = total - free - buffers - cache
+
+         * /proc/meminfo
+         *   total = MemTotal
+         *   code = total - free - buffers - cache (“used”)
+         *   buffer = Buffers
+         *   cached = Cached
+         *   free = MemFree
+         */
+        int mem_free = GetRamInKB(2);
+        int buffers = GetRamInKB(3);
+        int cached = GetRamInKB(4);
+        int swap_total = GetRamInKB(5);
+        int swap_free = GetRamInKB(6);
+        ret.code = (total_mem - mem_free - buffers - cached)/(float)total_mem;
+        ret.buffer = (buffers)/(float)total_mem;
+        ret.cached = (cached)/(float)total_mem;
+        ret.free = (mem_free)/(float)total_mem;
+        ret.swap = (swap_total - swap_free)/(float)swap_total;
+
+#ifdef DEBUG
+        printf("%u  %lf %lf  %lf %lf\n", total_mem,
+               ret.code, ret.cached, ret.free, ret.swap);
+#endif
+        memcpy(call_data, &ret, sizeof(MemStripChartCallbackData));
+}
+
+#endif