Fix binary formatting for integers 2 and 3

[mierenhoop]

Cosmopolitan's FormatBinary64 function gives incomplete representations of integers 2 and 3.
Shown in redbean's interpreter:

>: for i = 0, 8 do print(i, bin(i)) end
0       0
1       0b1
2       0b0
3       0b1
4       0b00000100
5       0b00000101
6       0b00000110
7       0b00000111
8       0b00001000

With the proposed patch, the ouput will look like this:

>: for i = 0, 8 do print(i, bin(i)) end
0       0
1       0b01
2       0b10
3       0b11
4       0b00000100
5       0b00000101
6       0b00000110
7       0b00000111
8       0b00001000

A different approach could be:

--- a/libc/fmt/formatbinary64.c
+++ b/libc/fmt/formatbinary64.c
@@ -21,7 +21,7 @@

 static inline int PickGoodWidth(unsigned x) {
   if (x < 16) {
-    if (x < 2) return 0;
+    if (x < 1) return 0;
     if (x < 8) return 7;
     return 15;
   } else {

Resulting:

0       0
1       0b1
2       0b00000010
3       0b00000011
4       0b00000100

[jart]

Looks good. Thanks for sending this. Could you write the email mentioned in https://github.com/jart/cosmopolitan/blob/master/CONTRIBUTING.md Thank you!

[jart]

Could you please fix test/libc/fmt/formatbinary64_test.c too? Thanks!

[mierenhoop]

Okay, now the tests are passing.

[jart]

Thanks!