1 files changed, 156 insertions, 0 deletions

diff --git a/masm/gen/section.c b/masm/gen/section.c
new file mode 100644
index 0000000..44f83f8
--- /dev/null
+++ b/masm/gen/section.c
@@ -0,0 +1,156 @@
+#include "../gen.h"
+
+#include <strings.h>
+#include <string.h>
+#include <stdlib.h>
+#include <merror.h>
+
+struct section_default {
+	char *name;
+	int name_len;
+
+	bool read;
+	bool write;
+	bool execute;
+	int alignment;
+};
+
+#define SECTION_DEFAULTS_LEN 7
+#define MAPPING(name, ...) {name, sizeof(name), __VA_ARGS__}
+static const struct section_default section_defaults[SECTION_DEFAULTS_LEN] = {
+	MAPPING(".text", true, false, true, 4),
+	MAPPING(".code", true, false, true, 4),
+	MAPPING(".data", true, true, false, 1),
+	MAPPING(".stack", true, true, false, 1),
+	MAPPING(".rodata", true, false, false, 1),
+	MAPPING(".bss", true, true, false, 1),
+	MAPPING(".robss", true, false, false, 1),
+};
+
+static void section_get_default_perm(struct section *sec, const char *name)
+{
+	for (int i = 0; i < SECTION_DEFAULTS_LEN; i++) {
+		const struct section_default *defaults = &section_defaults[i];
+		if (strncasecmp(name, defaults->name, defaults->name_len))
+			continue;
+		sec->read = defaults->read;
+		sec->write = defaults->write;
+		sec->execute = defaults->execute;
+		sec->align = defaults->alignment;
+		break;
+	}
+}
+
+int gen_get_section(struct generator *gen, struct section **res,
+		    struct string *name)
+{
+	/// find the section if it exists
+	for (size_t i = 0; i < gen->sections_len; i++) {
+		struct section *sec = &gen->sections[i];
+		if (sec->name.len != name->len)
+			continue;
+		if (strcmp(sec->name.str, name->str) != 0)
+			continue;
+		*res = sec;
+		return 0;
+	}
+
+	/// allocate a new one if it doesnt
+	size_t size = gen->sections_size ? gen->sections_size * 2 : 8;
+	void *new = realloc(gen->sections, size * sizeof(struct section));
+	if (new == NULL) {
+		PERROR("cannot realloc");
+		return 1;
+	}
+
+	gen->sections_size = size;
+	gen->sections = new;
+
+	struct section *sec = &gen->sections[gen->sections_len++];
+	if (section_init(sec, name))
+		return 1;
+
+	*res = sec;
+	return 0;
+}
+
+int section_init(struct section *sec, struct string *name)
+{
+	sec->len = 0;
+	sec->size = 0;
+	sec->align = 1;
+	sec->data = NULL;
+	sec->read = true;
+	sec->write = true;
+	sec->execute = false;
+
+	// set defaults
+	section_get_default_perm(sec, name->str);
+
+	// alloc reftab
+	if (reftab_init(&sec->reftab))
+		return 1;
+
+	// copy name
+	if (string_clone(&sec->name, name))
+		return 1;
+
+	return 0;
+}
+
+int section_extend(struct section *section, size_t space)
+{
+	size_t newlen = section->len + space;
+	if (newlen < section->size)
+		return M_SUCCESS;
+
+	size_t size = section->size ? section->size * 2 + newlen : newlen * 2;
+	void *new = realloc(section->data, size);
+	if (new == NULL) {
+		PERROR("cannot realloc");
+		return M_ERROR;
+	}
+	section->size = size;
+	section->data = new;
+
+	return M_SUCCESS;
+}
+
+int section_push(struct section *section, void *data, size_t len)
+{
+	size_t newlen = section->len + len;
+	size_t zeros = newlen % section->align;
+	if (zeros)
+		zeros = section->align - zeros;
+
+	if (section_extend(section, len + zeros))
+		return M_ERROR;
+
+	memset(section->data + section->len, 0, zeros);
+	memcpy(section->data + section->len + zeros, data, len);
+	section->len += len + zeros;
+
+	return M_SUCCESS;
+}
+
+int section_zero(struct section *section, size_t len)
+{
+	size_t zeros = section->len % section->align;
+	if (zeros)
+		zeros = section->align - zeros;
+
+	if (section_extend(section, len + zeros))
+		return M_ERROR;
+
+	memset(section->data + section->len, 0, len + zeros);
+	section->len += len + zeros;
+
+	return M_SUCCESS;
+}
+
+void section_free(struct section *section)
+{
+	reftab_free(&section->reftab);
+	string_free(&section->name);
+	free(section->data);
+}