refactor: c/ -> usr/, compiled program blobs out of the source tree

Userland sources live in usr/ (fits the Unix theme better than 'c').
SDCC output .bin blobs land in build/usr/ with the other build artifacts
instead of littering the source dir; programs.asm INCBINs them from there.
Byte-identical ROM.

1 files changed, 21 insertions, 0 deletions

diff --git a/usr/build.sh b/usr/build.sh
new file mode 100755
index 0000000..93815d2
--- /dev/null
+++ b/usr/build.sh
@@ -0,0 +1,21 @@
+#!/bin/sh
+# Build a gbos C program into a self-contained 16 KiB ROM-bank image.
+# SDCC native toolchain; crt0 linked FIRST so _start is the $4000 entry.
+# usage: usr/build.sh <prog.c> <out.bin>     (run from the repo root)
+set -e
+SRC="$1"; OUT="$2"; B=build/usr/obj
+LIBDIR=/usr/share/sdcc/lib/sm83
+mkdir -p "$B" "$(dirname "$OUT")"
+sdasgb -o "$B/crt0.rel" usr/crt0.s
+sdasgb -o "$B/libc.rel" usr/libc.s
+sdcc -msm83 -c -Iusr usr/libc.c -o "$B/libc_c.rel"
+sdcc -msm83 -c -Iusr "$SRC" -o "$B/prog.rel"
+# link: crt0 first (=> _start at 0x4000), then libc, program, and sm83 lib
+sdldgb -n -m -w -j -i "$B/prog.ihx" \
+       -b _CODE=0x4000 -b _DATA=0xa000 \
+       -k "$LIBDIR" -l sm83 \
+       "$B/crt0.rel" "$B/libc.rel" "$B/libc_c.rel" "$B/prog.rel"
+makebin -Z -p "$B/prog.ihx" "$B/prog.bin"
+dd if="$B/prog.bin" of="$OUT" bs=1024 skip=16 count=16 2>/dev/null
+echo "wrote $OUT ($(wc -c < "$OUT") bytes); entry:"
+grep -iE ' _start| _main' "$B/prog.map" | head -2