From ef88f0e530b898ebcb14f9e3dff1d58e83089ada Mon Sep 17 00:00:00 2001
From: user <user@clank>
Date: Thu, 16 Jul 2026 00:49:58 +0200
Subject: C toolchain: run SDCC-compiled C programs as gbos processes

- c/{gbos.h,crt0.s,libc.s,build.sh}: SDCC sm83 -> ROM-bank blob toolchain.
  libc syscall wrappers save/restore BC/DE/HL around rst $30 (trap clobbers
  them; SDCC expects them preserved).
- build via SDCC native asxxxx path (sdasgb/sdldgb), crt0 linked first so
  _start is the $4000 entry; blob INCBIN'd into a ROM bank.
- chello.c: prints a message + getpid() -> runs as 'chello' shell command.
- Makefile: auto-build c/*.bin, track as a dep of programs.o; gitignore blobs.
- README: document the C toolchain + the SDCC --asm=rgbds codegen bug that
  forced the native-toolchain approach.
- verified: '$ chello' -> 'hello from C on gbos!' / 'my pid is 2'.
---
 src/programs.asm | 13 +++++++++++++
 1 file changed, 13 insertions(+)

(limited to 'src/programs.asm')

diff --git a/src/programs.asm b/src/programs.asm
index d4ae89f..eabe56f 100644
--- a/src/programs.asm
+++ b/src/programs.asm
@@ -44,6 +44,15 @@ ProgHello:
     db "hello world!", $0D, $0A
 .msgend
 
+; -----------------------------------------------------------------------------
+; PROG_CHELLO (bank 5) - a program written in C, compiled with SDCC to a
+; self-contained ROM-bank image (crt0 + libc + code) and included verbatim.
+; Rebuild with: sh c/build.sh c/chello.c c/chello.bin
+; -----------------------------------------------------------------------------
+SECTION "prog_chello", ROMX[$4000], BANK[5]
+ProgChello:
+    INCBIN "c/chello.bin"
+
 ; -----------------------------------------------------------------------------
 ; PROG_SH (bank 3) - a tiny shell.
 ;   prompt -> read a line (with echo) -> match a command -> fork+exec+wait.
@@ -138,6 +147,8 @@ ProgSh:
     db PROG_WORKER
     db "hello", 0
     db PROG_HELLO
+    db "chello", 0
+    db PROG_CHELLO
     db 0                        ; terminator
 
 ; -----------------------------------------------------------------------------
@@ -178,3 +189,5 @@ ProgramTable::
     dw ProgSh
     db LOW(BANK(ProgHello)), HIGH(BANK(ProgHello))
     dw ProgHello
+    db LOW(BANK(ProgChello)), HIGH(BANK(ProgChello))
+    dw ProgChello
-- 
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