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/hex_print.c

@@ -0,0 +1,68 @@
+/*
+ * hex_print.c — compact hex print primitives ported from solid-c
+ * (third_party/solid-c/SRC/CLIB/STDLIB.ASM, modules hex8/hex16/hex32).
+ *
+ *   void hex8 (uint8_t  v) — always-2-digit  "00"      ..  "FF"
+ *   void hex16(uint16_t v) — always-4-digit  "0000"    .. "FFFF"
+ *   void hex32(uint32_t v) — always-8-digit  "00000000" .. "FFFFFFFF"
+ *
+ * Each nibble is emitted via the classic Z80 `cp 10 / sbc 0x69 / daa`
+ * trick — 5 bytes per nibble.  hex8 self-calls for the high nibble
+ * then falls through for the low nibble.  hex16/hex32 split into two
+ * hex8/hex16 calls.
+ *
+ * ESTEX PUTCHAR ($5B) preserves IX (empirically verified) so we skip
+ * the usual push/pop ix around the RST.
+ */
+
+#include <stdio.h>
+#include <stdint.h>
+
+void hex8(uint8_t v) __naked
+{
+    (void)v;
+    __asm
+        ;; A = v on entry.
+        push  af
+        rra
+        rra
+        rra
+        rra
+        call  _hex8_digit
+        pop   af
+    _hex8_digit:
+        and   a, #0x0F
+        cp    a, #10
+        sbc   a, #0x69
+        daa
+        ld    c, #0x5B
+        rst   #0x10
+        ret
+    __endasm;
+}
+
+void hex16(uint16_t v) __naked
+{
+    (void)v;
+    __asm
+        ;; HL = v on entry.
+        ld    a, h
+        push  hl
+        call  _hex8
+        pop   hl
+        ld    a, l
+        jp    _hex8                ; tail-call
+    __endasm;
+}
+
+void hex32(uint32_t v) __naked
+{
+    (void)v;
+    __asm
+        ;; HL = high16, DE = low16 on entry (SDCC HLDE).
+        push  de
+        call  _hex16
+        pop   hl
+        jp    _hex16               ; tail-call
+    __endasm;
+}