Changeset c4cfe4c in mainline for kernel/genarch/src/drivers/ns16550/ns16550.c

Timestamp:

2025-04-17T16:01:16Z (5 days ago)

Author:

Jiří Zárevúcky <zarevucky.jiri@…>

Branches:

master

Children:

888c06e

Parents:

1db4e2ae (diff), 250a435 (diff)
Note: this is a merge changeset, the changes displayed below correspond to the merge itself.
Use the (diff) links above to see all the changes relative to each parent.

git-author:

Jiří Zárevúcky <zarevucky.jiri@…> (2025-04-17 15:51:11)

git-committer:

Jiří Zárevúcky <zarevucky.jiri@…> (2025-04-17 16:01:16)

Message:

Convert kernel console writing to byte arrays

More buffer per buffer (the original char32_t buffer takes up four
times as much space for the same amount of backlog, which is wasteful).
It is also faster, possibly thanks to bigger chunks being processed in bulk.
Gonna try to figure out if the locking can be improved further.

Also changed to use a syscall for reading KIO buffer from uspace,
to allow better synchronization.

File:

• kernel/genarch/src/drivers/ns16550/ns16550.c (modified) (1 diff)

kernel/genarch/src/drivers/ns16550/ns16550.c

@@ -112 +112 @@
 }
 
-static void ns16550_putuchar(outdev_t *dev, char32_t ch)
+static void ns16550_write(outdev_t *dev, const char *s, size_t n)
 {
         ns16550_instance_t *instance = (ns16550_instance_t *) dev->data;
 
-        if ((!instance->parea.mapped) || (console_override)) {
-                if (ch == '\n')
+        if (instance->parea.mapped && !console_override)
+                return;
+
+        const char *top = s + n;
+        assert(top >= s);
+
+        for (; s < top; s++) {
+                if (*s == '\n')
                         ns16550_sendb(instance, '\r');
 
-                if (ascii_check(ch))
-                        ns16550_sendb(instance, (uint8_t) ch);
-                else
-                        ns16550_sendb(instance, U_SPECIAL);
+                ns16550_sendb(instance, (uint8_t) *s);
         }
 }
 
 static outdev_operations_t ns16550_ops = {
-        .write = ns16550_putuchar,
+        .write = ns16550_write,
         .redraw = NULL
 };