libc review: mem/, stdio/, fixes in sprinter-cc and FILE shim

libc/mem/:
  • Split bank_io.c into bank_io_w3.c (existing W3 helpers, base 0xC000,
    port 0xE2) and bank_io_w1.c (new mirror through W1, base 0x4000,
    port 0xA2).  Two .rel files so DCE picks only the needed group:
    a W3-only user pulls ~70 bytes instead of all 134.  W1 variants are
    `--memory tiny`-only (any other mode runs code from W1 or uses W1
    for the banked-code segment, swapping it crashes).
  • mem_alloc.c: add CF=err checks for mem_free_block and mem_get_page
    (were silently ignored), per-function docstrings on alloc/free/
    get_page/info, drop the confused "wait wrong order" comment in
    mem_info.  Header sprinter_mem.h gets matching per-function doc.

libc/stdio/:
  • Add hex_print.c (hex8/hex16/hex32, ~26 bytes) and dec_print.c
    (dec8/dec16/dec32, ~170 bytes) ported from solid-c STDLIB.ASM.
    Replaces the printf("%u"/"%X") wrappers in solid_helpers.c that
    dragged in the 3-5 KB printf machinery.
    - hex* use the classic cp 10 / sbc 0x69 / daa nibble→ASCII trick;
      hex8 self-calls for the high nibble, hex16/hex32 tail-call hex8.
    - dec32 is the master routine; dec8/dec16 jump into shared entry
      points (__dec_entry3 / __dec_entry5).  32-bit subtract-power-of-10
      keeps the high 16 bits in HL alt (shadow set).
    - DISCOVERY: ESTEX PUTCHAR ($5B) on our Sprinter build preserves
      the main register set + IX but CLOBBERS the shadow set
      (BC'/DE'/HL').  solid-c's original code assumed otherwise and
      garbled output for values ≥ 6 digits.  Fix: save/restore HL alt
      around the RST 10 in _dec_emit_or_skip.  Documented in
      memory/estex_putchar_abi.md.
  • file.c: drop stdaux/stdprn (no Sprinter printer API), change
    stdin/stdout/stderr fd markers to 0/-1/-2 (positive fds clash with
    ESTEX OPEN return values), add TODO header pointing at v2 buffered
    FILE rewrite (see docs/TODO.md for the Solid-C reference struct).

bin/sprinter-cc:
  • --memory big and --memory huge now always use crt0_banked.s (was:
    only with --bank flags), matching docs/memory_modes_implemented.md.
    When the user has no --bank flags, generate a tiny stub with
    `const uint8_t n_banks = 0;` and assemble bank.s for _bank_pages.
    Without this fix, openenv with --memory big could not see the
    estex_file_handle symbol exported by crt0_banked.

examples/openenv:
  • Add usage of estex_file_handle to confirm the crt0_banked startup-
    info is reachable.  Local extern decl — keeps the symbol out of
    sprinter.h since it only exists in big/huge builds.

examples/dec_test:
  • New regression test covering hex8/16/32 and dec8/16/32 across the
    interesting boundary values.

.gitignore: add .kilo/ (editor session cache).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

libc/stdio/file.c

@@ -1,14 +1,40 @@
 /*
- * file.c — minimal unbuffered FILE * implementation on top of the
- * POSIX-style fd I/O (open/read/write/lseek/close).
+ * file.c — *** PROVISIONAL ***  minimal unbuffered FILE * implementation
+ *                                on top of POSIX-style fd I/O
+ *                                (open/read/write/lseek/close).
  *
- * No buffering: each fputc/fgetc maps to one read/write syscall.  For
- * heavy-throughput code, prefer fread/fwrite with a sizable buffer or
- * the raw fd I/O directly.
+ * ============================================================
+ *  TODO (v2): replace with a proper BUFFERED implementation.
+ *  See docs/TODO.md  /  Solid-C reference layout:
  *
- * stdin/stdout/stderr are STATIC sentinel FILEs with fd=-1 and the
- * _F_CONIN/_F_CONOUT flags set; fputc/fgetc detect them and call
- * putchar()/getchar() (which already do CR/LF mapping and ESTEX calls).
+ *    typedef struct {
+ *        uint   flags;     // +0..1  file status flags
+ *        int    level;     // +2..3  empty/fill level of buffer
+ *        char  *curp;      // +4..5  current active pointer
+ *        int    fd;        // +6..7  underlying low-level fd
+ *        char  *buffer;    // +8..9  data transfer buffer
+ *        char   hold;      // +10    ungetc byte if no buffer
+ *        short  token;     // +11..12  reserved
+ *        char   dummy;     // +13    reserved
+ *    } FILE;
+ *
+ *  The current implementation maps each fputc/fgetc to one read/write
+ *  syscall — fine for correctness checks, awful for throughput.  Issues
+ *  3/4/5 from the stdio-review (fwrite short-write flag, fgets n=1,
+ *  mode_to_flags break) are deferred until that rewrite.
+ * ============================================================
+ *
+ * stdin/stdout/stderr are STATIC sentinel FILEs flagged with
+ * _F_CONIN/_F_CONOUT; fputc/fgetc detect them and call putchar() /
+ * getchar() which already handle CR/LF translation and ESTEX calls.
+ *
+ * Their fd fields are 0 / -1 / -2.  Negative values were chosen because
+ * ESTEX OPEN can return small positive fds (1, 2, …) for ordinary
+ * files — if we marked stdout/stderr with fd=1/2 a real file could
+ * collide with their identifier.  fd=0 for stdin is kept (POSIX-style)
+ * because ESTEX does not return 0.  Even so, none of these fd fields
+ * is ever passed to a syscall — the _F_CONIN/_F_CONOUT flags drive
+ * the dispatch.
  */
 
 #include <stdio.h>
@@ -19,17 +45,13 @@
 #include <errno.h>
 
 /* ---- console pseudo-streams ----------------------------------------*/
-static FILE _stdin  = { -1, _F_READ  | _F_CONIN  };
-static FILE _stdout = { -2, _F_WRITE | _F_CONOUT };
-static FILE _stderr = { -3, _F_WRITE | _F_CONOUT };
-static FILE _stdaux = { -4, _F_WRITE | _F_CONOUT };
-static FILE _stdprn = { -5, _F_WRITE | _F_CONOUT };
+static FILE _stdin  = {  0, _F_READ  | _F_CONIN  };
+static FILE _stdout = { -1, _F_WRITE | _F_CONOUT };
+static FILE _stderr = { -2, _F_WRITE | _F_CONOUT };
 
 FILE *const stdin  = &_stdin;
 FILE *const stdout = &_stdout;
 FILE *const stderr = &_stderr;
-FILE *const stdaux = &_stdaux;
-FILE *const stdprn = &_stdprn;
 
 /* ---- fopen / fclose -------------------------------------------------*/