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, 17 insertions, 2 deletions

diff --git a/src/proc.asm b/src/proc.asm
index a2b1368..ab1c807 100644
--- a/src/proc.asm
+++ b/src/proc.asm
@@ -221,7 +221,10 @@ ProcCreate::
     ld [hl+], a                 ; PROC_WRAMB
     xor a
     ld [hl+], a                 ; PROC_PARENT
-    ld [hl], a                  ; PROC_EXIT
+    ld [hl+], a                 ; PROC_EXIT
+    ld a, STD_CONSOLE
+    ld [hl+], a                 ; PROC_STDIN  = console
+    ld [hl], a                  ; PROC_STDOUT = console
 
     ; build the initial stack frame in the task's RAM bank
     ld a, [wTmpEntry]
@@ -438,7 +441,19 @@ sys_fork::
     ld [hl+], a
     ; PROC_EXIT = 0
     xor a
-    ld [hl], a
+    ld [hl+], a
+    ; PROC_STDIN / PROC_STDOUT = inherit from parent
+    ld a, [wCurProc]
+    add PROC_STDIN
+    ld e, a
+    ld a, [wCurProc+1]
+    adc 0
+    ld d, a
+    ld a, [de]
+    ld [hl+], a                 ; child STDIN = parent STDIN
+    inc de
+    ld a, [de]
+    ld [hl], a                  ; child STDOUT = parent STDOUT
 
     ; ---- return to the parent with child pid ----
     ld a, [wForkUserSP]