ffprobe: refactor value_string() to accept an unit_value struct

The new design allows to specialize the format for continuos time values
and discrete values. In particular, allows to print integer values like
"12" rather than "12.000".

Prettify, simplify parsing for integer values.

ffprobe.c

@@ -63,12 +63,27 @@ void exit_program(int ret)
     exit(ret);
 }
 
-static char *value_string(char *buf, int buf_size, double val, const char *unit)
+struct unit_value {
+    union { double d; int i; } val;
+    const char *unit;
+};
+
+static char *value_string(char *buf, int buf_size, struct unit_value uv)
 {
-    if (unit == unit_second_str && use_value_sexagesimal_format) {
+    double vald;
+    int show_float = 0;
+
+    if (uv.unit == unit_second_str) {
+        vald = uv.val.d;
+        show_float = 1;
+    } else {
+        vald = uv.val.i;
+    }
+
+    if (uv.unit == unit_second_str && use_value_sexagesimal_format) {
         double secs;
         int hours, mins;
-        secs  = val;
+        secs  = vald;
         mins  = (int)secs / 60;
         secs  = secs - mins * 60;
         hours = mins / 60;
@@ -76,25 +91,31 @@ static char *value_string(char *buf, int buf_size, double val, const char *unit)
         snprintf(buf, buf_size, "%d:%02d:%09.6f", hours, mins, secs);
     } else if (use_value_prefix) {
         const char *prefix_string;
-        int index;
+        int index, l;
 
-        if (unit == unit_byte_str && use_byte_value_binary_prefix) {
-            index = (int) (log(val)/log(2)) / 10;
+        if (uv.unit == unit_byte_str && use_byte_value_binary_prefix) {
+            index = (int) (log(vald)/log(2)) / 10;
             index = av_clip(index, 0, FF_ARRAY_ELEMS(binary_unit_prefixes) -1);
-            val /= pow(2, index*10);
+            vald /= pow(2, index*10);
             prefix_string = binary_unit_prefixes[index];
         } else {
-            index = (int) (log10(val)) / 3;
+            index = (int) (log10(vald)) / 3;
             index = av_clip(index, 0, FF_ARRAY_ELEMS(decimal_unit_prefixes) -1);
-            val /= pow(10, index*3);
+            vald /= pow(10, index*3);
             prefix_string = decimal_unit_prefixes[index];
         }
 
-        snprintf(buf, buf_size, "%.3f%s%s%s", val, prefix_string || show_value_unit ? " " : "",
-                 prefix_string, show_value_unit ? unit : "");
+        if (show_float || vald != (int)vald) l = snprintf(buf, buf_size, "%.3f", vald);
+        else                                 l = snprintf(buf, buf_size, "%d",   (int)vald);
+        snprintf(buf+l, buf_size-l, "%s%s%s", prefix_string || show_value_unit ? " " : "",
+                 prefix_string, show_value_unit ? uv.unit : "");
     } else {
-        snprintf(buf, buf_size, "%f%s%s", val, show_value_unit ? " " : "",
-                 show_value_unit ? unit : "");
+        int l;
+
+        if (show_float) l = snprintf(buf, buf_size, "%.3f", vald);
+        else            l = snprintf(buf, buf_size, "%d",   (int)vald);
+        snprintf(buf+l, buf_size-l, "%s%s", show_value_unit ? " " : "",
+                 show_value_unit ? uv.unit : "");
     }
 
     return buf;
@@ -105,7 +126,8 @@ static char *time_value_string(char *buf, int buf_size, int64_t val, const AVRat
     if (val == AV_NOPTS_VALUE) {
         snprintf(buf, buf_size, "N/A");
     } else {
-        value_string(buf, buf_size, val * av_q2d(*time_base), unit_second_str);
+        double d = val * av_q2d(*time_base);
+        value_string(buf, buf_size, (struct unit_value){.val.d=d, .unit=unit_second_str});
     }
 
     return buf;
@@ -611,7 +633,8 @@ static void writer_register_all(void)
 #define print_str(k, v)         writer_print_string(w, k, v)
 #define print_ts(k, v)          writer_print_string(w, k, ts_value_string  (val_str, sizeof(val_str), v))
 #define print_time(k, v, tb)    writer_print_string(w, k, time_value_string(val_str, sizeof(val_str), v, tb))
-#define print_val(k, v, unit)   writer_print_string(w, k, value_string     (val_str, sizeof(val_str), v, unit))
+#define print_val(k, v, u)      writer_print_string(w, k, value_string     (val_str, sizeof(val_str), \
+                                                    (struct unit_value){.val.i = v, .unit=u}))
 #define print_section_header(s) writer_print_section_header(w, s)
 #define print_section_footer(s) writer_print_section_footer(w, s)
 #define show_tags(metadata)     writer_show_tags(w, metadata)