build: prefix include deps into build/

scan_includes now supports --build-prefix so generated INCLUDE/INCBIN dependencies are emitted as /… when missing in the source tree.

Makefile

@@ -161,8 +161,12 @@ $(info $(shell $(MAKE) -C tools))
 
 # Redirect dependencies that are generated as part of the build into $(BUILDDIR)/.
 #
-# Heuristic: if a dependency path exists in the source tree, keep it as-is;
-# otherwise, assume it is generated into $(BUILDDIR)/.
+# For INCLUDE/INCBIN dependencies, this logic now lives in tools/scan_includes
+# via its --build-prefix option.
+#
+# For other rules (e.g. compression), keep the Makefile-side heuristic:
+# if a dependency path exists in the source tree, keep it as-is; otherwise,
+# assume it is generated into $(BUILDDIR)/.
 define map_build_deps
 $(strip \
 	$(foreach dep,$1,\
@@ -173,10 +177,12 @@ $(strip \
 )
 endef
 
-preinclude_deps := includes.asm $(call map_build_deps,$(shell tools/scan_includes includes.asm))
+SCAN_INCLUDES := tools/scan_includes --build-prefix $(BUILDDIR)
+
+preinclude_deps := includes.asm $(shell $(SCAN_INCLUDES) includes.asm)
 define DEP
 
-$1: $2 $$(call map_build_deps,$$(shell tools/scan_includes $2)) $(preinclude_deps) | $(OBJDIR)/rgbdscheck.o
+$1: $2 $$(shell $(SCAN_INCLUDES) $2) $(preinclude_deps) | $(OBJDIR)/rgbdscheck.o
 	@mkdir -p $$(dir $$@)
 	$$(RGBASM) $$(RGBASMFLAGS) -o $$@ $$<
 endef

tools/scan_includes.c

@@ -1,18 +1,55 @@
 #define PROGRAM_NAME "scan_includes"
-#define USAGE_OPTS "[-h|--help] [-s|--strict] filename.asm"
+#define USAGE_OPTS "[-h|--help] [-s|--strict] [-b|--build-prefix dir] filename.asm"
 
 #include "common.h"
 
 #include <ctype.h>
+#include <unistd.h>
 
-void parse_args(int argc, char *argv[], bool *strict) {
+static bool has_prefix(const char *s, const char *prefix) {
+	if (!prefix || !*prefix) {
+		return false;
+	}
+	size_t prefix_len = strlen(prefix);
+	if (strlen(s) < prefix_len) {
+		return false;
+	}
+	if (strncmp(s, prefix, prefix_len)) {
+		return false;
+	}
+	if (prefix[prefix_len - 1] == '/') {
+		return true;
+	}
+	return s[prefix_len] == '/' || s[prefix_len] == '\0';
+}
+
+static char *join_prefix(const char *prefix, const char *path) {
+	if (!prefix || !*prefix) {
+		size_t len = strlen(path) + 1;
+		char *out = xmalloc(len);
+		memcpy(out, path, len);
+		return out;
+	}
+	size_t prefix_len = strlen(prefix);
+	bool needs_slash = prefix[prefix_len - 1] != '/';
+	size_t len = prefix_len + (needs_slash ? 1 : 0) + strlen(path) + 1;
+	char *out = xmalloc(len);
+	snprintf(out, len, "%s%s%s", prefix, needs_slash ? "/" : "", path);
+	return out;
+}
+
+void parse_args(int argc, char *argv[], bool *strict, const char **build_prefix) {
 	struct option long_options[] = {
+		{"build-prefix", required_argument, 0, 'b'},
 		{"strict", no_argument, 0, 's'},
 		{"help", no_argument, 0, 'h'},
 		{0}
 	};
-	for (int opt; (opt = getopt_long(argc, argv, "sh", long_options)) != -1;) {
+	for (int opt; (opt = getopt_long(argc, argv, "b:sh", long_options)) != -1;) {
 		switch (opt) {
+		case 'b':
+			*build_prefix = optarg;
+			break;
 		case 's':
 			*strict = true;
 			break;
@@ -25,7 +62,7 @@ void parse_args(int argc, char *argv[], bool *strict) {
 	}
 }
 
-void scan_file(const char *filename, bool strict) {
+void scan_file(const char *filename, bool strict, const char *build_prefix) {
 	errno = 0;
 	FILE *f = fopen(filename, "rb");
 	if (!f) {
@@ -88,10 +125,17 @@ void scan_file(const char *filename, bool strict) {
 					size_t length = strcspn(ptr, "\"");
 					ptr += length + 1;
 					include_path[length] = '\0';
-					printf("%s ", include_path);
-					if (is_include) {
-						scan_file(include_path, strict);
+					const char *printed_path = include_path;
+					char *prefixed_path = NULL;
+					if (build_prefix && !has_prefix(include_path, build_prefix) && access(include_path, F_OK) != 0) {
+						prefixed_path = join_prefix(build_prefix, include_path);
+						printed_path = prefixed_path;
 					}
+					printf("%s ", printed_path);
+					if (is_include) {
+						scan_file(include_path, strict, build_prefix);
+					}
+					free(prefixed_path);
 				} else {
 					fprintf(stderr, "%s: no file path after INC%s\n", filename, is_include ? "LUDE" : "BIN");
 					// Continue to process a comment
@@ -109,7 +153,8 @@ void scan_file(const char *filename, bool strict) {
 
 int main(int argc, char *argv[]) {
 	bool strict = false;
-	parse_args(argc, argv, &strict);
+	const char *build_prefix = NULL;
+	parse_args(argc, argv, &strict, &build_prefix);
 
 	argc -= optind;
 	argv += optind;
@@ -117,6 +162,6 @@ int main(int argc, char *argv[]) {
 		usage_exit(1);
 	}
 
-	scan_file(argv[0], strict);
+	scan_file(argv[0], strict, build_prefix);
 	return 0;
 }