shell: I/O redirection (>/<) and pipes (|); rewrite shell in C

- kernel I/O routing: PCB gains PROC_STDIN/PROC_STDOUT (default console $FF),
  inherited across fork. KGetc/KPutc route read/write/putc to the console or a
  file fd. New syscalls: putc(16), setin(17), setout(18), lookup(19).
  read/write now go through the routing; putc/puts/nl use SYS_PUTC.
- sys_lookup + NameTable move command-name resolution into the kernel.
- shell rewritten in C (c/sh.c): tokenizes a line, parses > / < / |, and drives
  fork+setin/setout+exec+wait. Pipes run as 'a > __pipe ; b < __pipe' (temp
  file). asm shell + cmdtab removed; StrEqual/SkipName kept for sys_lookup.
- libc: fork/exec/wait/setin/setout/lookup wrappers.
- verified: echo>file, cat file, wc<file, cat readme|wc -l, echo ...|wc.

1 files changed, 51 insertions, 16 deletions

diff --git a/c/libc.s b/c/libc.s
index a26042e..857a16d 100644
--- a/c/libc.s
+++ b/c/libc.s
@@ -25,11 +25,11 @@ _getargs:
 	ld	c, l
 	ret
 
-	;; void putc(char c /*A*/)
+	;; void putc(char c /*A*/) -> stdout via SYS_PUTC
 _putc:
-	ld	(0xff01), a
-	ld	a, #0x81
-	ld	(0xff02), a
+	ld	e, a
+	ld	c, #16			; SYS_PUTC
+	rst	#0x30
 	ret
 
 	;; void puts(const char *s /*DE*/) - write until NUL (no newline)
@@ -37,22 +37,22 @@ _puts:
 1$:	ld	a, (de)
 	or	a
 	ret	z
-	ld	(0xff01), a
-	ld	a, #0x81
-	ld	(0xff02), a
+	push	de
+	ld	e, a
+	ld	c, #16			; SYS_PUTC
+	rst	#0x30
+	pop	de
 	inc	de
 	jr	1$
 
-	;; void nl(void) - CRLF
+	;; void nl(void) - CRLF via stdout
 _nl:
-	ld	a, #0x0d
-	ld	(0xff01), a
-	ld	a, #0x81
-	ld	(0xff02), a
-	ld	a, #0x0a
-	ld	(0xff01), a
-	ld	a, #0x81
-	ld	(0xff02), a
+	ld	e, #0x0d
+	ld	c, #16			; SYS_PUTC
+	rst	#0x30
+	ld	e, #0x0a
+	ld	c, #16
+	rst	#0x30
 	ret
 
 	;; unsigned char strlen(const char *s /*DE*/) -> A
@@ -132,3 +132,38 @@ _fremove:
 	ld	c, #15			; SYS_REMOVE
 	rst	#0x30
 	ret
+
+	.globl _fork, _exec, _wait, _setin, _setout, _lookup
+	;; unsigned char fork(void) -> A (child pid in parent, 0 in child)
+_fork:
+	ld	c, #1			; SYS_FORK
+	rst	#0x30
+	ret
+	;; void exec(unsigned char id /*A*/) - never returns
+_exec:
+	ld	b, a
+	ld	c, #6			; SYS_EXEC
+	rst	#0x30
+	ret
+	;; unsigned char wait(void) -> A (reaped pid)
+_wait:
+	ld	c, #7			; SYS_WAIT
+	rst	#0x30
+	ret
+	;; void setin(unsigned char fd /*A*/)
+_setin:
+	ld	b, a
+	ld	c, #17			; SYS_SETIN
+	rst	#0x30
+	ret
+	;; void setout(unsigned char fd /*A*/)
+_setout:
+	ld	b, a
+	ld	c, #18			; SYS_SETOUT
+	rst	#0x30
+	ret
+	;; unsigned char lookup(const char *name /*DE*/) -> A (prog id or $FF)
+_lookup:
+	ld	c, #19			; SYS_LOOKUP
+	rst	#0x30
+	ret