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Initial commit

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Signed-off-by: Robert Allan James <robert.allan.james@gmail.com>
This commit is contained in:
Robert Allan James
2026-09-01 12:07:32 -04:00
parent d2a0305703
commit 58c59e87e5
11 changed files with 218 additions and 16 deletions
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src/starkernel/repl.c
+51 -3
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@@ -141,6 +141,16 @@ 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. */
console_ensure_line_start();
/* 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
@@ -498,11 +508,22 @@ int sk_console_key_available(void)
* 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 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';
console_fb_draw_cursor(); /* show the cursor at the bare prompt, before any input */
@@ -531,6 +552,33 @@ int sk_console_readline(char *buf, int size, VM *active_vm)
g_last_beat_tick = now;
sk_repl_idle(active_vm);
}
/*
* Re-anchor the prompt (FABRIC.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-3.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)
{
console_puts(SK_PROMPT_TEXT);
console_fb_draw_cursor();
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
@@ -720,7 +768,7 @@ int sk_repl_step(VM *vm)
console_puts(SK_PROMPT_TEXT);
}
sk_console_readline(input, sizeof(input), vm);
sk_console_readline(input, sizeof(input), vm, 1);
if (input[0] == '\0') {
console_puts(" ok\n");
@@ -763,7 +811,7 @@ void sk_repl_run(VM *vm)
* step()'s matching comment above. */
console_puts(SK_PROMPT_TEXT);
sk_console_readline(input, sizeof(input), active);
sk_console_readline(input, sizeof(input), active, 1);
if (input[0] == '\0') {
console_puts(" ok\n");