/* StarForth — Steady-State Virtual Machine Runtime Copyright (c) 2023–2025 Robert A. James All rights reserved. Licensed under the StarForth License, Version 1.0 */ /** * repl.c - Emergency FORTH REPL for LithosAnanke kernel * * Direct adaptation of src/repl.c for the freestanding kernel context. * Replaces libc stdio (fgets/printf/fflush) with HAL serial I/O: * - Input: console_getc() non-blocking poll with local echo and backspace * - Output: console_puts() / console_putc() * * Idle spin: polls console_getc() and services the adaptive heartbeat. * The timer ISR's top half (heartbeat_tick()) latches one * sample per interrupt; the idle spin drains it every * iteration via heartbeat_service() (item 0.8, FABRIC-0.md §26) * and calls sk_repl_idle() once per SK_IDLE_BEAT_INTERVAL ticks * for coarser subsystem dispatch. On QEMU TCG the ISR must fire * for ticks to advance — check "Heartbeat: N ticks" in the * serial log to confirm. * * Runs with interrupts enabled so the APIC heartbeat fires normally. * Designed as the last thing kernel_main does before the idle loop. */ #include "starkernel/repl.h" #include "console.h" #include "log.h" #include "vm.h" #include "version.h" #include "starkernel/timer.h" #include "starkernel/arch.h" #include "starkernel/xhci_driver.h" #include "starkernel/blkio_usb.h" #include "starkernel/homeblocks_sig.h" #include "starkernel/capsule_birth.h" #include "starkernel/capsule_zuse_boot.h" #include "starkernel/capsule_wirebind.h" #include "starkernel/capsule_run.h" #include "starkernel/vm/bootstrap/sk_vm_bootstrap.h" #include "block_subsystem.h" #include "word_source/include/keyboard_words.h" #include "word_source/include/block_words.h" #include "freestanding/stdio.h" #include #include /* FABRIC-0.md 4.4: "ok>" (including its trailing space) renders in bright * cyan, 0x55FFFF -- reuses FB_ANSI_PALETTE[14]. Sent as a real SGR escape * so it colors both the framebuffer (parsed by vt100.c's apply_sgr()) and * any ANSI-aware serial terminal, per 4.4c's "identical on both" goal. */ #define SK_PROMPT_TEXT "\x1b[38;2;85;255;255mok> \x1b[39m" const char lithos_version[64] = LITHOS_VERSION_STR; /* FABRIC-0.md §27.8/4.4s, unblocked 2026-09-04: extends the prompt to * "[VM name] (user) ok>" (e.g. "[Hera] (zuse) ok>") whenever an * identity is currently attached -- Zuse (mama_vm->zuse_session; there * is only ever one, so no username lookup needed) or a regular WIREBIND * user (capsule_wirebind_attached_username()). Checked independently of * which VM's own bracket console.c is currently showing: both identities * are console-level attach state, not per-VM dictionary state, so the * segment reflects "who is at the console" the same way regardless of * which VM you've USE'd into. Prints nothing (bare "ok> ", today's * existing format, unchanged) when neither is attached -- Hera's own * documented normal steady state (FABRIC-2.md §D.2). */ static void sk_print_prompt(void) { VM *mama_vm = (VM *)sk_get_mama_vm(); const char *username; if (mama_vm && mama_vm->zuse_session) { console_puts("(zuse) "); } else if ((username = capsule_wirebind_attached_username()) != (const char *)0) { console_puts("("); console_puts(username); console_puts(") "); } console_puts(SK_PROMPT_TEXT); } /*=========================================================================== * USE-word dispatch: which VM receives REPL input. * * NULL means "use the REPL's own vm parameter" (default — Mama). * Set via sk_repl_set_active_vm(); read by sk_repl_run() each iteration. *===========================================================================*/ static VM *g_repl_active_vm = (void *)0; void sk_repl_set_active_vm(VM *vm) { g_repl_active_vm = vm; } VM *sk_repl_get_active_vm(void) { return g_repl_active_vm; } /*=========================================================================== * Currently attached home-blocks device: mirrors g_repl_active_vm's own * shape (FABRIC-2.md §F.9's own precedent for this exact accessor). Set * once sk_repl_idle()'s own attach handling confirms HOMEBLOCKS_SIG_OK * below; cleared on detach. RUNCAP (§F.6/§F.18) and, later, BINDSTEP's * re-verify-live check (§F.9) both need this -- neither lives in this * file, and usb_blk_dev/xdev below are function-static, invisible outside * sk_repl_idle() without an accessor like this one. *===========================================================================*/ static blkio_dev_t *g_homeblocks_dev = (void *)0; static homeblocks_sig_t g_homeblocks_sig; static int g_homeblocks_sig_valid = 0; blkio_dev_t *sk_repl_get_homeblocks_dev(void) { return g_homeblocks_sig_valid ? g_homeblocks_dev : (void *)0; } const homeblocks_sig_t *sk_repl_get_homeblocks_sig(void) { return g_homeblocks_sig_valid ? &g_homeblocks_sig : (void *)0; } /* The currently attached USB block device, regardless of whether it * checks out as a recognized home-blocks drive -- MINT (§F.8/§F.19) * targets a blank/unminted drive, which by definition never sets * g_homeblocks_dev above (that only latches on HOMEBLOCKS_SIG_OK). * Set once blk_subsys_attach_device() succeeds below, cleared on detach * alongside g_homeblocks_dev. */ static blkio_dev_t *g_attached_blk_dev = (void *)0; blkio_dev_t *sk_repl_get_attached_blk_dev(void) { return g_attached_blk_dev; } /*=========================================================================== * Idle heartbeat service * * Called from sk_console_readline()/sk_console_getkey() when heartbeat_ticks() has advanced by at least * SK_IDLE_BEAT_INTERVAL since the last service call. Extend this function * as higher-level subsystems (msg_fabric, capsule scheduler) come online. * * TODO: cadence policy and subsystem dispatch belong in Compudynamics once * that layer governs cooperative VM execution. *===========================================================================*/ #define SK_IDLE_BEAT_INTERVAL 100u /* ticks between idle service calls (1 s at 100 Hz) */ static uint64_t g_last_beat_tick; /* zero-initialized (BSS) */ /* Cursor blink, 2026-09-05: the framebuffer cursor (now a thin vertical * bar, vt100.c's vt100_draw_cursor()) blinks on/off every * SK_CURSOR_BLINK_INTERVAL ticks while sk_console_readline()'s idle loop * is spinning -- i.e. whenever nothing has been typed for that long, * whether sitting at a bare prompt or paused mid-edit. g_cursor_visible * tracks which half of the blink cycle is current; sk_cursor_show() below * is the single place that resets the cycle back to "on" and redraws -- * every deterministic draw site (fresh prompt, echoed character, * backspace) calls it instead of vt100_draw_cursor() directly, so typing * always shows a solid cursor rather than possibly landing mid-blink. */ #define SK_CURSOR_BLINK_INTERVAL 50u /* ticks between blink toggles (500 ms at 100 Hz) */ static uint64_t g_cursor_blink_tick; /* zero-initialized (BSS) */ static int g_cursor_visible = 1; static void sk_cursor_show(void) { g_cursor_visible = 1; g_cursor_blink_tick = heartbeat_ticks(); console_fb_draw_cursor(); } /* Reentrancy guards for the MSG-TICK pump inside sk_repl_idle(). * * sk_repl_idle() runs vm_interpret(mama, ...) (below) to VM-EXEC MSG-TICK * into every live child VM (FABRIC-2.md Phase C). But sk_repl_idle() is * itself called from the blocking KEY/EXPECT/QUERY reads (sk_console_getkey() * / sk_console_readline(), which run *from inside* the executing VM's own * vm_interpret once a FORTH word reads input mid-line). vm_interpret() is * not reentrant -- it resets the VM's single input_buffer/input_pos/ * input_length (vm_core.c) on entry. Calling vm_interpret(mama, ...) at that * point would re-enter mama's interpreter mid-parse and silently truncate * the rest of the line; if the pump's own MSG-TICK work then triggers another * blocking read, it would also recurse unboundedly. Two flags keep the pump * off every path that could re-enter an interpreter: * - g_mama_interpreting: set while Hera is executing a dispatched line, so * the pump defers to the next safe (prompt) boundary. * - g_idle_pump_active: belt-and-suspenders; stops recursive re-entry * from inside the pump's own vm_interpret call. */ static int g_mama_interpreting; /* zero-initialized (BSS) */ static int g_idle_pump_active; /* zero-initialized (BSS) */ static void sk_repl_idle(VM *active_vm) { /* Close any dangling output line before this bottom half emits its own * chatter (xhci attach/detach progress, block-subsystem notices). If we * are mid-prompt-line -- the REPL started the attach while sitting at * "ok> " -- a bare console_println() would otherwise glue its text onto * the prompt and inherit no {VMName} prefix (g_line_start is 0). A * fresh line first keeps every idle line prefix-tagged and readable, * matching what an interactive typing session expects. No-op when the * console is already at a line boundary. * * FABRIC-2.md §I.9 fix, 2026-09-05: this newline is now deferred (see * console_ensure_line_start()'s own doc comment) -- it only actually * reaches the console if something below really prints. tx_before_idle * lets this function tell "nothing happened" apart from "something did" * the same way the reanchor check further up this file already does, * so a beat with nothing to report can cancel the deferred newline * before returning, leaving the bare prompt line completely untouched * instead of visibly snapping it to a fresh blank line every ~1s. */ console_ensure_line_start(); uint64_t tx_before_idle = console_tx_count(); /* Artemis Milestone 2d: xHCI Event Ring servicing. This is exactly the * "interrupt-driven, coarse cadence, cheap early-exit" trigger Section * U item 6 asked for -- xhci_poll_events() is a no-op read (loop * condition false immediately) whenever nothing is pending, and this * hook already runs at a deliberately coarser cadence than the raw * per-tick ISR (SK_IDLE_BEAT_INTERVAL, ~1s at 100Hz), matching "quick * check... done... ignore what we can... done." A no-op call if no * controller was found/brought up (xhci_bringup() never latched a * device). */ xhci_poll_events(); /* Milestone 2h: a Mass Storage/BOT device finished SET_CONFIGURATION * during the xhci_poll_events() call just above -- run the * synchronous capacity query + block-subsystem attach here, strictly * after that call has already returned (see bot_msc_attach_pending's * own doc comment in xhci_driver.h for why: xhci_bot_wait_for_idle()'s * busy-wait -- which blkio_usb_open_msc() uses internally -- must * never run from inside xhci_poll_events()'s own call frame). */ xhci_dev_t *xdev = xhci_get_dev(); static blkio_dev_t usb_blk_dev; /* single-device scope, matching the xHCI * driver's own; referenced by both the * attach and detach handling below. */ if (xdev && xdev->bot_msc_attach_pending) { xdev->bot_msc_attach_pending = 0; uint32_t slot_id = xdev->bot_msc_attach_slot_id; int rc = blkio_usb_open_msc(&usb_blk_dev, xdev, slot_id); if (rc == 0) { /* FABRIC-2.md Milestone 4: warn on blank/foreign/unrecognized * media -- the "warn" half. No "refuse" half yet: blkio_usb.c * has no SCSI WRITE(10) support at all (Milestone 2's biggest * open item), so there is no write path today to refuse -- * only read-only attach, which is also the general-purpose USB * block I/O path this repo already relies on for unrelated * testing, not exclusively a home-blocks identity workflow. * Refusing attach on blank media here would break that * legitimate use without protecting anything real yet. Refuse * belongs on the write path, once WRITE(10) gives it something * to gate. * * HOMEBLOCKS_SIG_START_FBLOCK (devblock 1): the real, final * location -- GPT was dropped permanently, this is not an * interim value (FABRIC-2.md §F.8/§F.13). */ homeblocks_sig_t sig; homeblocks_sig_result_t sig_rc = homeblocks_sig_check(&usb_blk_dev, HOMEBLOCKS_SIG_START_FBLOCK, &sig); switch (sig_rc) { case HOMEBLOCKS_SIG_OK: log_message(LOG_DEBUG, "xhci: USB drive recognized as a home-blocks drive"); g_homeblocks_dev = &usb_blk_dev; g_homeblocks_sig = sig; g_homeblocks_sig_valid = 1; break; case HOMEBLOCKS_SIG_BLANK: log_message(LOG_DEBUG, "xhci: USB drive not recognized (blank or foreign media) -- read-only general use only"); break; case HOMEBLOCKS_SIG_BAD_VERSION: log_message(LOG_WARN, "xhci: USB drive has a home-blocks header of an unrecognized version -- read-only general use only"); break; case HOMEBLOCKS_SIG_BAD_CRC: log_message(LOG_WARN, "xhci: USB drive has a home-blocks header that fails its checksum (corrupt or tampered) -- read-only general use only"); break; case HOMEBLOCKS_SIG_READ_ERROR: log_message(LOG_ERROR, "xhci: USB drive signature check failed to read the device -- read-only general use only"); break; } /* FABRIC-2.md §F.20/§F.21: Zuse is thumbdrive-resident now, * not system-resident -- this is the only point in the boot * lifecycle a just-attached drive's sig result is known, so * genesis-mint/attach-authenticate has to happen from here, * not as a one-shot kernel_main.c step (a thumbdrive can't * be detected before the REPL's own idle polling exists to * detect it). No-ops immediately if Zuse already has a real * identity this boot. */ capsule_zuse_boot_try_attach(&usb_blk_dev, sig_rc, &sig, (VM *)sk_get_mama_vm()); /* FABRIC-2.md §F.5/§F.23 (WIREBIND): the real thumbdrive- * attach call site for a regular (non-Zuse) identity -- * verify-then-birth-then-pair, replacing the RUNCAP-TEST/ * PAIR-TEST diagnostic words that exercised each piece by * hand. Only meaningful for a drive that actually checked * out (HOMEBLOCKS_SIG_OK); capsule_wirebind_try_attach() * itself no-ops for a genesis-mode Zuse drive (no cert * region) or before Zuse has authenticated this boot. */ if (sig_rc == HOMEBLOCKS_SIG_OK) { capsule_wirebind_try_attach(&usb_blk_dev, &sig, (VM *)sk_get_mama_vm()); } } if (rc == 0 && blk_subsys_attach_device(&usb_blk_dev) == BLK_OK) { xdev->bot_msc_attached = 1; g_attached_blk_dev = &usb_blk_dev; } else { log_message(LOG_ERROR, "xhci: USB MSC block-subsystem attach failed"); } } /* Milestone 2h hot-detach: the device disconnected (PORTSC, inside the * xhci_poll_events() call above) after having actually attached. * blk_subsys_detach_device() is local block_subsystem.c bookkeeping -- * no device round-trip, so it wouldn't strictly need to run outside * xhci_poll_events()'s own call frame -- but handling it here anyway * matches the attach path's shape and keeps xhci.c decoupled from * block_subsystem.c (see bot_msc_detach_pending's own doc comment). */ if (xdev && xdev->bot_msc_detach_pending) { xdev->bot_msc_detach_pending = 0; blk_subsys_detach_device(&usb_blk_dev); if (g_homeblocks_dev == &usb_blk_dev) { g_homeblocks_dev = (void *)0; g_homeblocks_sig_valid = 0; } if (g_attached_blk_dev == &usb_blk_dev) { g_attached_blk_dev = (void *)0; } /* FABRIC-2.md §F.10 decision 2 (UNCLEAN, closed alongside EJECT): * the device is already gone -- no-op if WIREBIND never had * anything tracked (general-purpose USB use, not a home-blocks * identity drive). */ capsule_wirebind_unclean_detach(); /* FABRIC-2.md §I.8, re-scoped 2026-09-04: Zuse logs out on device * removal exactly like a WIREBIND user -- no-op if the device * that just left wasn't hers. */ capsule_zuse_boot_logout((VM *)sk_get_mama_vm()); } /* FABRIC-0.md/FABRIC-1.md Section V item 6: "a cheap 'anything dirty? * no? done' block-sync check", the same "interrupt-driven, coarse * cadence, cheap early-exit" trigger shape as the xHCI servicing * above -- this was the one piece of that design already fully * specified and waiting for this hook to actually be non-empty. * blk_vm_flush_all() (block_words.c, the same code SAVE-BUFFERS * itself runs) is cheap to call when nothing is dirty -- every * check inside is a small fixed-size scan, no disk I/O happens * unless something genuinely needs writing -- so no separate * "is anything dirty" pre-check is needed here. * * active_vm is passed in by the caller (sk_console_readline(), itself passed * through from sk_repl_run()/sk_repl_step()'s own already-resolved * VM) rather than read via sk_repl_get_active_vm() here -- that * accessor returns NULL whenever Tripod's USE word hasn't redirected * it, which is the common case, not "no VM is active." An earlier * version of this code called sk_repl_get_active_vm() directly and * silently no-op'd for exactly that reason, confirmed live: a BUFFER * write with no UPDATE, followed by an idle wait and an abrupt kill, * did not survive a reboot until this fix. */ blk_vm_flush_all(active_vm); /* FABRIC-2.md §I.2, built 2026-09-04: heat/wear-leveling migration * trigger -- one linear scan of Artemis's own device per idle tick * (same ~1 Hz SK_IDLE_BEAT_INTERVAL cadence this whole function * already runs at, chosen so a hot devblock is caught proactively * rather than only on a failed write). See block_subsystem.c's own * doc comment on blk_migration_idle_check() for what's built (heat- * based relocation) vs. deliberately left open (overflow-triggered * migration, needs a call site threaded from WIREBIND). */ blk_migration_idle_check(); /* FABRIC-2.md §I.2's own overflow trigger, closed 2026-09-05: the * call site named above, now built. Same cadence, same idle-tick * neighbor -- see capsule_wirebind_overflow_idle_check()'s own doc * comment for what it does and why it's a one-time extension, not a * growth loop. */ capsule_wirebind_overflow_idle_check(); /* FABRIC-2.md Phase C (2026-08-28): distributed messaging pump. Every * live VM except Hera herself now owns its own MSG-ARENA/CH-ARENA and * MSG-TICK word (see capsules/common/messaging.4th) instead of only * Hermes having one -- "fully distributed, Hera pumps each VM's * drain" was the confirmed design. Hera is excluded: she never loads * common:messaging.4th (kernel_main.c's own comment at the Hermes- * birth call site explains why -- the STADIUM-* primitives it needs * are deliberately never registered in her own dictionary, to keep * her dict_hash off item 4.1's baseline), so MSG-TICK is genuinely * absent there, not just untried. She is the only VM with a * persistent idle tick, so she walks the registry once per idle beat * and VM-EXECs MSG-TICK into every OTHER live VM's own dictionary. */ VM *mama = (VM *)sk_get_mama_vm(); /* Reentrancy guard: never run the pump while mama is mid-interpret * (a dispatched line, or recursively from within the pump's own * vm_interpret). vm_interpret() clobbers the VM's single input * buffer, so re-entering it here while KEY/EXPECT/QUERY blocks inside * a live parse truncates the rest of that line. Deferring the MSG-TICK * drain to the next prompt boundary is safe -- draining is best-effort * and simply resumes next beat. */ if (g_mama_interpreting || g_idle_pump_active) { if (console_tx_count() == tx_before_idle) { console_cancel_deferred_line_start(); } return; } g_idle_pump_active = 1; { uint32_t count = capsule_vm_registry_count(); uint32_t i; for (i = 0; i < count; i++) { VMRegistryEntry ent; if (capsule_vm_registry_get_by_index(i, &ent) != 0) continue; if (ent.state != VM_STATE_LIVE) continue; if (ent.vm_ptr == (void *)mama) continue; static const char PFX[] = "S\" MSG-TICK\" S\" "; static const char SFX[] = "\" VM-EXEC"; char cmd[128]; size_t p = 0; size_t name_len = strlen(ent.name); if (name_len > VM_NAME_MAX - 1u) name_len = VM_NAME_MAX - 1u; memcpy(cmd + p, PFX, sizeof(PFX) - 1u); p += sizeof(PFX) - 1u; memcpy(cmd + p, ent.name, name_len); p += name_len; memcpy(cmd + p, SFX, sizeof(SFX) - 1u); p += sizeof(SFX) - 1u; cmd[p] = '\0'; vm_interpret(mama, cmd); } } g_idle_pump_active = 0; if (console_tx_count() == tx_before_idle) { console_cancel_deferred_line_start(); } } /*=========================================================================== * FABRIC-0.md item 4.4v: keyboard-to-REPL bridge. * * Translates sk_key_event_poll()'s converged Linux-keycode-namespace * stream (keyboard_words.c -- one implementation shared with KEY-EVENT, * live-verified on all three architectures per item 4.3.5f) into the same * byte stream sk_console_readline() already reads from console_getc(): -1 for * "nothing ready", else a raw ASCII byte with '\n'/0x7F meaning the same * thing they mean for the serial path below. * * Table covers exactly the keys a line editor needs -- letters, digits, * the standard US-QWERTY punctuation row, space, enter, backspace, tab * (for the Ctrl+TAB toggle interception, 4.4y/4.4u step 8) -- not full * keyboard coverage. Keycodes are Linux input-event-codes.h values, * confirmed against this build host's own header, not guessed (§25.0 * rule 4). Index 0 means "no mapping"; arrows/F-keys/etc. fall through * unmapped and are silently dropped, consistent with this REPL's * append/backspace-only editing model (4.4u: no mid-line cursor * movement). *===========================================================================*/ #define SK_KBD_TABLE_SIZE 98u /* highest keycode used below is KEY_RIGHTCTRL=97 */ static const char sk_kbd_unshifted[SK_KBD_TABLE_SIZE] = { [2]='1',[3]='2',[4]='3',[5]='4',[6]='5',[7]='6',[8]='7',[9]='8',[10]='9',[11]='0', [12]='-',[13]='=', [16]='q',[17]='w',[18]='e',[19]='r',[20]='t',[21]='y',[22]='u',[23]='i',[24]='o',[25]='p', [26]='[',[27]=']', [30]='a',[31]='s',[32]='d',[33]='f',[34]='g',[35]='h',[36]='j',[37]='k',[38]='l', [39]=';',[40]='\'',[41]='`',[43]='\\', [44]='z',[45]='x',[46]='c',[47]='v',[48]='b',[49]='n',[50]='m', [51]=',',[52]='.',[53]='/', [57]=' ', }; static const char sk_kbd_shifted[SK_KBD_TABLE_SIZE] = { [2]='!',[3]='@',[4]='#',[5]='$',[6]='%',[7]='^',[8]='&',[9]='*',[10]='(',[11]=')', [12]='_',[13]='+', [16]='Q',[17]='W',[18]='E',[19]='R',[20]='T',[21]='Y',[22]='U',[23]='I',[24]='O',[25]='P', [26]='{',[27]='}', [30]='A',[31]='S',[32]='D',[33]='F',[34]='G',[35]='H',[36]='J',[37]='K',[38]='L', [39]=':',[40]='"',[41]='~',[43]='|', [44]='Z',[45]='X',[46]='C',[47]='V',[48]='B',[49]='N',[50]='M', [51]='<',[52]='>',[53]='?', [57]=' ', }; #define SK_KEY_BACKSPACE 14u #define SK_KEY_TAB 15u #define SK_KEY_ENTER 28u #define SK_KEY_LEFTSHIFT 42u #define SK_KEY_RIGHTSHIFT 54u #define SK_KEY_LEFTALT 56u #define SK_KEY_RIGHTALT 100u static int g_kbd_shift_down; /* zero-initialized (BSS) */ static int g_kbd_alt_down; /* Drains and translates one physically-typed key. Modifier state persists * across calls (a real keyboard's shift/alt state is global, not * per-line). Alt+TAB is intercepted here and drives the graphics/text * toggle directly (console_fb_toggle_graphics(), the same state-machine * transition the ALT+TAB FORTH word calls) -- never reaches the line * buffer as a character either way. */ static int sk_kbd_getc(void) { uint16_t keycode; int pressed; while (sk_key_event_poll(&keycode, &pressed)) { if (keycode == SK_KEY_LEFTSHIFT || keycode == SK_KEY_RIGHTSHIFT) { g_kbd_shift_down = pressed; continue; } if (keycode == SK_KEY_LEFTALT || keycode == SK_KEY_RIGHTALT) { g_kbd_alt_down = pressed; continue; } if (!pressed) continue; /* only act on press/repeat */ if (keycode == SK_KEY_TAB) { if (g_kbd_alt_down) console_fb_toggle_graphics(); continue; /* bare TAB: not mapped, same as arrows/F-keys */ } if (keycode == SK_KEY_ENTER) return '\n'; if (keycode == SK_KEY_BACKSPACE) return 0x7F; if (keycode < SK_KBD_TABLE_SIZE) { char c = g_kbd_shift_down ? sk_kbd_shifted[keycode] : sk_kbd_unshifted[keycode]; if (c) return (unsigned char)c; } /* unmapped keycode -- drop and keep draining */ } return -1; } /* One raw byte from either input source (serial console or the keyboard- * event bridge), non-blocking, -1 if neither has one ready right now. Not * itself a FORTH word -- the shared byte-fetch underneath sk_console_getkey()/ * sk_console_key_available() (the standard dictionary's KEY/?TERMINAL, wired * through shim.c's getchar()) and sk_console_readline() (QUERY/EXPECT, wired * through shim.c's fgets()) alike. */ static int sk_console_getc_raw(void) { int c = console_getc(); if (c < 0) c = sk_kbd_getc(); /* FABRIC-0.md 4.4v: second source, same buffer */ return c; } /* One-byte pushback so sk_console_key_available() can peek without losing * the byte -- ?TERMINAL must be non-destructive (a caller checks readiness, * then still expects KEY to return that same key). */ static int g_console_pending_key = -1; /* KEY's real body (shim.c's getchar() calls this): blocks until a key is * available, servicing the heartbeat/idle loop while waiting -- same * cadence sk_console_readline() already uses below, so a KEY call mid-word * never stalls the heartbeat or Hera's own idle dispatch. No echo -- that's * the caller's job, same as any standard KEY implementation. */ int sk_console_getkey(VM *active_vm) { for (;;) { int c; if (g_console_pending_key >= 0) { c = g_console_pending_key; g_console_pending_key = -1; } else { c = sk_console_getc_raw(); } if (c >= 0) return c; heartbeat_service(); uint64_t now = heartbeat_ticks(); if (now - g_last_beat_tick >= SK_IDLE_BEAT_INTERVAL) { g_last_beat_tick = now; sk_repl_idle(active_vm); } arch_relax(); } } /* ?TERMINAL's real body (sf_terminal_ready(), shim.c): non-blocking peek -- * a single poll, no idle-servicing loop (a false result must return * immediately, not block). Buffers a found byte in g_console_pending_key so * a following sk_console_getkey() returns the exact same key, not a * different/later one. */ int sk_console_key_available(void) { if (g_console_pending_key >= 0) return 1; int c = sk_console_getc_raw(); if (c >= 0) { g_console_pending_key = c; return 1; } return 0; } /*=========================================================================== * sk_console_readline - line read from serial console with echo * * Non-blocking poll of console_getc(). While no character is ready the idle * spin services the adaptive heartbeat at SK_IDLE_BEAT_INTERVAL tick cadence. * Supports backspace (0x7F and \b) and ignores other control characters. * Returns the number of characters placed in buf (not counting '\0'). * * Public (declared in repl.h): shim.c's fgets()/QUERY's own real body call * this directly -- same line-editing behavior for a mid-word EXPECT/QUERY as * for the REPL's own top-level prompt, since it's the same underlying * console. Any g_console_pending_key left over from a ?TERMINAL peek is * consumed first so a line read never drops a byte ?TERMINAL already saw. * @param reanchor_prompt nonzero from the REPL's own prompt sites (which * print SK_PROMPT_TEXT immediately before): re-print the prompt whenever an * idle bottom half wrote to the console while this call blocked at the bare * prompt (see the re-anchor block in the idle branch). shim.c's fgets() * passes 0 -- its prompt context is caller-owned. *===========================================================================*/ int sk_console_readline(char* buf, int size, VM* active_vm, int reanchor_prompt) { int n = 0; /* TX counter value right after the caller printed its prompt. Any * console output that lands while this readline blocks (heartbeat * status, sk_repl_idle()'s USB attach/detach chatter) pushes the * counter past this mark and away from a bare prompt; when that * happens, re-anchor the prompt (below). */ uint64_t prompt_tx_mark = console_tx_count(); buf[0] = '\0'; sk_cursor_show(); /* show the cursor at the bare prompt, before any input */ for (;;) { int c; if (g_console_pending_key >= 0) { c = g_console_pending_key; g_console_pending_key = -1; } else { c = sk_console_getc_raw(); } if (c < 0) { /* Service the heartbeat bottom half every idle iteration, not * gated by SK_IDLE_BEAT_INTERVAL (item 0.8, FABRIC-0.md §26): * heartbeat_service() drains at most one latched sample per * call, so a coarse gate here would silently lose or merge * samples between ISR-latched ticks. sk_repl_idle() below is * a separate, deliberately coarser cadence for higher-level * subsystem dispatch, unrelated to sample fidelity. */ heartbeat_service(); uint64_t now = heartbeat_ticks(); /* n == 0 gate: sk_repl_idle() opens with console_ensure_line_start(), * closing off a dangling prompt line before any chatter it might * print (xhci attach/detach, block-sync, MSG-TICK pump). Before the * FABRIC-2.md §I.9 fix (2026-09-05), that newline was unconditional * and immediate, so it fired on every elapsed SK_IDLE_BEAT_INTERVAL * regardless of whether sk_repl_idle() actually had anything to * print -- including mid-edit (n > 0, characters typed but Enter * not yet pressed), visually snapping the in-progress line to a * fresh blank one, indistinguishable from Enter having been * pressed. console_ensure_line_start()'s newline is now deferred * and self-cancelling when nothing follows it (console.c), which * fixes that regardless of n -- but this gate is kept for its own, * independent reason: deferring the *whole* idle beat while a line * is being edited (same n > 0 guard the prompt reanchor below * already uses) means a genuine xhci/block-sync/MSG-TICK event * cannot interrupt output mid-line while the user is actively * typing, only delaying that servicing by at most one more * interval, which its own "coarse cadence, cheap early-exit" * design already tolerates. */ if (n == 0 && now - g_last_beat_tick >= SK_IDLE_BEAT_INTERVAL) { g_last_beat_tick = now; sk_repl_idle(active_vm); } /* Blink the cursor while idle (no key ready this iteration), * regardless of n -- a real terminal blinks whether sitting at * a bare prompt or paused mid-edit. sk_cursor_show() (called * from every deterministic draw site below and at entry) resets * this cycle to "on" on every real keystroke, so typing never * looks like it landed mid-blink. */ if (now - g_cursor_blink_tick >= SK_CURSOR_BLINK_INTERVAL) { g_cursor_blink_tick = now; g_cursor_visible = !g_cursor_visible; if (g_cursor_visible) console_fb_draw_cursor(); else console_fb_erase_cursor(); } /* * Re-anchor the prompt (FABRIC-0.md 4.4a unified prompt: print * only "ok> " here -- console_putc() auto-prefixes the current * [VMName] on a fresh line). When an idle bottom half above * pushed output past prompt_tx_mark, the console cursor is now * below/after new lines and the "ok> " the caller printed has * been scrolled or buried -- once the flood passes, the screen * and serial log would end on a stale line with no prompt * (FABRIC-2.md: the bare prompt must be the last thing shown * while the REPL sits idle). Reprinting it restores that * invariant. Skipped while a line is being edited (n > 0) so * partial echo stays attached to its own prompt; shim.c's * fgets() (QUERY/EXPECT/ACCEPT) calls in with reanchor_prompt * == 0 for the same reason -- its prompt line is caller-owned * text, not the REPL's. Each silent beat leaves the mark * unchanged, so the final state after the chatter dies down is * a fresh prompt on the last visible line, cursor on it. */ if (reanchor_prompt && n == 0 && console_tx_count() != prompt_tx_mark) { sk_print_prompt(); sk_cursor_show(); prompt_tx_mark = console_tx_count(); } /* * Do NOT use hlt here: QEMU single-threaded TCG can't process * its APIC timer callbacks while the guest CPU is halted (the * event loop and the TCG thread share the same OS thread). * Interrupts are delivered at TB boundaries in a tight loop. * On real hardware a wfi/hlt would be appropriate; add it here * under an #ifdef REAL_HARDWARE guard when that path is needed. */ arch_relax(); /* PAUSE — reduce power, maintain tight poll */ continue; } if (c == '\r' || c == '\n') { console_fb_erase_cursor(); /* leaving this cell without drawing a char over it */ console_putc('\n'); break; } /* backspace: DEL (0x7F) or BS (0x08) */ if ((c == 0x7F || c == '\b') && n > 0) { n--; buf[n] = '\0'; /* VT100 erase: move back, overwrite with space, move back again */ console_putc('\b'); console_putc(' '); console_putc('\b'); sk_cursor_show(); continue; } if (c < 0x20) continue; /* ignore other control characters */ if (n >= size - 1) continue; /* buffer full — drop character */ buf[n++] = (char)c; buf[n] = '\0'; console_putc((char)c); /* echo */ sk_cursor_show(); } buf[n] = '\0'; return n; } /*=========================================================================== * sk_repl - FORTH REPL * * FABRIC-2.md §F.20/§F.21 (2026-08-28): the unauthenticated emergency-CLI * ACL bypass this REPL used to grant itself on Hera's own bare prompt is * retired -- every word runs under ordinary ACL enforcement here now, * console identity included. emergency_console still exists as a field * (vm.h) and is still set, briefly, by the genuine C-level VM fault * handler (EMERGENCY_CONSOLE_ENABLED build flag) for crash recovery -- * that's a distinct, narrower mechanism this REPL no longer touches. * * Mirrors vm_repl() from src/repl.c: * - Reads a line via sk_console_readline (non-blocking, heartbeat-serviced) * - Calls vm_interpret * - Prints " ok" or " ERROR" * - When EMERGENCY_CONSOLE_ENABLED=1: resets vm->error and loops (recovery) * - When EMERGENCY_CONSOLE_ENABLED=0: halts VM on error (no fallthrough surface) *===========================================================================*/ #if !EMERGENCY_CONSOLE_ENABLED static void sk_fault_handler(VM *vm) { console_println("VM fault — emergency console disabled; halting"); vm->halted = 1; } #endif /*=========================================================================== * sk_repl_dispatch_line - console-VM + user-VM pair relay (FABRIC-2.md * Phase F, 2026-08-28). * * If `vm`'s own registered name has a live "~user" counterpart, * this is a console session: relay the raw line as a real, async * CONSOLE-CMD-EVENT message (common:messaging.4th) instead of * interpreting it directly -- "every line is a message," not a * C-level redirect. This is one particular consumer of the general * VM-to-VM messaging system built in Phase C: any VM can already * MSG-SEND to any other VM for its own reasons regardless of a human * ever being at a physical console at all; this hook only wires the * physical-terminal-input path into that same general mechanism, it * doesn't gate or replace it. * * Falls back to direct vm_interpret() (today's unchanged behavior) when * there's no live paired user VM, or when the line contains a `"` * character this simple S"-embedding can't safely carry yet (a known * v1 limitation -- warned about, not silently mishandled). *===========================================================================*/ /* USE (FABRIC-2.md §F.24) is a REPL-control word, not a command for * whatever VM happens to be paired to a console -- it must always run * on the active VM directly, never get relayed as a message. Real * FORTH syntax always puts USE last (S" name" USE), so a trailing- * token match is a reliable, non-tokenizing-required check: trim * trailing whitespace, then confirm the line ends with "USE" as its * own word (preceded by whitespace or the whole line). */ static int sk_repl_line_calls_use(const char *input) { size_t len = strlen(input); while (len > 0 && (input[len - 1] == ' ' || input[len - 1] == '\t')) len--; if (len < 3) return 0; if (input[len - 3] != 'U' || input[len - 2] != 'S' || input[len - 1] != 'E') return 0; return (len == 3) || (input[len - 4] == ' ' || input[len - 4] == '\t'); } static void sk_repl_dispatch_line(VM *vm, const char *input) { /* H1 reentrancy guard: while this dispatched line executes on Hera * herself, sk_repl_idle() must defer its MSG-TICK pump -- calling * vm_interpret(mama, ...) from inside a mid-line KEY/EXPECT would * re-enter mama's interpreter and clobber its in-flight input buffer * (see the guard's comment at sk_repl_idle()). A child VM's console * turn leaves mama idle, so the pump stays safe there and the guard is * only latched for Hera. */ int on_mama = (vm == (VM *)sk_get_mama_vm()); int saved = g_mama_interpreting; if (on_mama) g_mama_interpreting = 1; if (sk_repl_line_calls_use(input)) { vm_interpret(vm, input); goto out; } const char *vn = console_get_vm_name(); if (vn) { char paired_name[VM_NAME_MAX + 8]; size_t vnlen = strlen(vn); if (vnlen + 6 <= sizeof(paired_name)) { memcpy(paired_name, vn, vnlen); memcpy(paired_name + vnlen, "~user", 6); /* includes NUL */ VMRegistryEntry paired; if (capsule_vm_find_by_name(paired_name, &paired) == 0 && paired.state == VM_STATE_LIVE) { if (strchr(input, '"')) { console_println("console: line contains '\"' -- can't relay " "as a message safely yet, interpreting directly"); } else { char cmd[INPUT_BUFFER_SIZE + 64]; /* to-index 3: the fixed convention this console's own * VM-NAME-REG entry for its paired user VM uses (set * once at pairing time -- see the pairing word). */ int n = snprintf(cmd, sizeof(cmd), "CONSOLE-CMD-EVENT 0 3 S\" %s\" 0 MSG-SEND", input); if (n > 0 && (size_t)n < sizeof(cmd)) { vm_interpret(vm, cmd); goto out; } } } } } vm_interpret(vm, input); out: g_mama_interpreting = saved; } /*=========================================================================== * sk_repl_step - Execute one REPL turn on a VM and return. * * Prints the VM's prompt, reads one input line, interprets it, prints * ok/ERROR, then returns. Used by the Compudynamics VM-STEP primitive * so Hera can give a single REPL quantum to any child VM without * surrendering control for the full sk_repl_run() loop. * * Returns 1 if the VM is still running, 0 if it halted during this turn. *===========================================================================*/ int sk_repl_step(VM *vm) { char input[INPUT_BUFFER_SIZE]; /* FABRIC-0.md 4.4w: matches the strip's input width */ if (!vm || vm->halted) return 0; { /* Unified prompt (FABRIC-0.md 4.4a): console_putc()'s existing per-line * "[VMName] " prefix (console.c, g_active_vm_name) already supplies the * bracket -- print only "ok> " here, don't build a second one. * emergency_console is no longer set from here (FABRIC-2.md §F.20/ * §F.21: the emergency-CLI ACL bypass is retired) -- it's driven * only by the genuine C-level fault handler now (vm.c's own * emergency-fault-recovery use, EMERGENCY_CONSOLE_ENABLED). Every * word run from this REPL, Hera's bare prompt included, goes * through ordinary ACL enforcement. FABRIC-0.md 4.4s (2026-09-04): * sk_print_prompt() extends this with a "(user)" segment when an * identity is attached -- see its own doc comment. */ sk_print_prompt(); } sk_console_readline(input, sizeof(input), vm, 1); if (input[0] == '\0') { console_puts(" ok\n"); return vm->halted ? 0 : 1; } sk_repl_dispatch_line(vm, input); /* ABORT stops mid-line but leaves the flag set for the caller to * consume -- this REPL step is that boundary. Clear it here so the * next line isn't silently refused by vm_interpret's own check. */ vm->abort_requested = 0; if (vm->error) { console_puts(" ERROR\n"); vm->error = 0; } else { console_puts(" ok\n"); } return vm->halted ? 0 : 1; } void sk_repl_run(VM *vm) { char input[INPUT_BUFFER_SIZE]; /* FABRIC-0.md 4.4w: matches the strip's input width */ VM *active; vm->halted = 0; while (!vm->halted) { /* USE may redirect input to a different VM each iteration */ active = g_repl_active_vm ? g_repl_active_vm : vm; /* Unified prompt (FABRIC-0.md 4.4a): console_putc()'s existing per-line * "[VMName] " prefix (console.c, g_active_vm_name) already supplies the * bracket -- print only "ok> " here, don't build a second one. * emergency_console is no longer set from here (FABRIC-2.md §F.20/ * §F.21: the emergency-CLI ACL bypass is retired) -- see sk_repl_ * step()'s matching comment above. FABRIC-0.md 4.4s (2026-09-04): * sk_print_prompt() extends this with a "(user)" segment. */ sk_print_prompt(); sk_console_readline(input, sizeof(input), active, 1); if (input[0] == '\0') { console_puts(" ok\n"); continue; } sk_repl_dispatch_line(active, input); /* ABORT stops mid-line but leaves the flag set for the caller to * consume -- this REPL step is that boundary. Clear it here so the * next line isn't silently refused by vm_interpret's own check. */ active->abort_requested = 0; if (active->error) { console_puts(" ERROR\n"); active->error = 0; } else { console_puts(" ok\n"); } } } void sk_repl(VM *vm) { /* FABRIC-0.md item 4.4j: boot and POST (both already returned by the time * sk_repl() is called) stay on font_8x16.c/VT100 by design; the * interactive REPL -- this function -- is the boundary where TTF-TEXT * takes over. One-shot: console_fb_enable_ttf() no-ops on any later * call. */ console_fb_enable_ttf(); console_println(lithos_version); console_puts("StarForth Version "); console_println(STARFORTH_VERSION); console_println(""); console_println("StarForth Emergency CLI"); console_println("FORTH-79 interpreter — type BYE or power off to exit"); console_println(""); sk_repl_run(vm); }