printf: add support for 'B' format (C23).

This prints integers in binary, with an optional '0B' prefix. It is specified but optional in C23.

The similar 'b' format (differing only in the case used for the '0b' prefix) is required in C23, but not yet implemented here, since 'b' has historically been used for something different in ORCA/C. The C23 'b' format would be simple to implement with small adjustments to the entry code, but I plan to provide compatibility support to pick between the two versions based on the standard in use.

stdio.asm

@@ -4232,9 +4232,10 @@ lb1      clc                            restore the original argp+4
 *  ~Format_x - format a hexadecimal number (lowercase output)
 *  ~Format_X - format a hexadecimal number (uppercase output)
 *  ~Format_p - format a pointer
+*  ~Format_B - format a binary number (uppercase prefix, if any)
 *
 *  Inputs:
-*        ~altForm - use a leading '0' (octal) or '0x' (hex)?
+*        ~altForm - use a leading '0' (octal), '0x' (hex), or '0b' (bin)?
 *        ~fieldWidth - output field width
 *        ~paddChar - padd character
 *        ~leftJustify - left justify the output?
@@ -4250,26 +4251,31 @@ lb1      clc                            restore the original argp+4
 argp     equ   7                        argument pointer
 
          lda   #3                       use 3 bits per output character
+         bra   cn0a
+
+~Format_B entry
+         ldx   #0
+bn0      lda   #1                       use 1 bit per output character
          bra   cn0
 
 ~Format_x entry
 ;
 ;  Set the "or" value; this is used to set the case of character results
 ;
-         lda   #$20*256
-         sta   ~orVal
+         ldx   #$20*256
          bra   hx0
 
 ~Format_p entry
          inc   ~isLong
 ~Format_X entry
-         stz   ~orVal
+         ldx   #0
 hx0      lda   #4                       use 4 bits per output character
 
 ;
 ;  Initialization
 ;
-cn0      sta   bitsPerChar
+cn0      stx   ~orVal
+cn0a     sta   bitsPerChar
          stz   ~hexPrefix               assume we won't lead with 0x
          stz   ~sign                    ignore the sign flag
          lda   #'  '                    initialize the string to blanks
@@ -4294,22 +4300,26 @@ cn2      lda   [argp]
          beq   cn2a
          and   #$00FF
 cn2a     sta   ~num
-         ldx   bitsPerChar              if doing hex format then
-         cpx   #3
-         beq   cn2b
+         ldy   bitsPerChar              if doing hex or bin format then
+         cpy   #3
+         beq   cn2d
          ldx   ~altForm                   if alt form has been selected then
-         beq   cn2b
+         beq   cn2d
          ora   ~num+2                       if value is not 0 then
          ora   ~num+4
          ora   ~num+6
-         beq   cn2b
-         lda   #'X0'                          set hex prefix to '0X' or '0x'
-         ora   ~orVal
+         beq   cn2d
+         dey                                  if doing bin format than
+         bne   cn2b
+         lda   #'B0'                            set bin prefix to '0B' or '0b'
+         bra   cn2c                           else
+cn2b     lda   #'X0'                            set hex prefix to '0X' or '0x'
+cn2c     ora   ~orVal
          sta   ~hexPrefix
 ;
 ;  Convert the number to an ASCII string
 ;
-cn2b     ldy   #l:~str-1                set up the character index
+cn2d     ldy   #l:~str-1                set up the character index
 cn3      lda   #' 0'                    roll off 4 bits
          ldx   bitsPerChar
 cn4      lsr   ~num+6
@@ -4337,7 +4347,7 @@ cn5      dey
          ora   ~num
          bne   cn3
 ;
-;  If a leading '0x' is required, be sure we include one
+;  If a leading '0' is required, be sure we include one
 ;
          lda   bitsPerChar              if doing octal format then
          cmp   #3
@@ -4943,6 +4953,7 @@ fList    dc    c'%',a'~Format_Percent'  %
          dc    c'g',a'~Format_g'        g
          dc    c'G',a'~Format_G'        G
          dc    c'n',a'~Format_n'        n
+         dc    c'B',a'~Format_B'        B
          dc    c's',a'~Format_s'        s
          dc    c'b',a'~Format_b'        b
          dc    c'P',a'~Format_P'        P