refactor: flatten src and migrate to meson

1 files changed, 1252 insertions, 0 deletions

diff --git a/src/nasm.c b/src/nasm.c
new file mode 100644
index 0000000..15f5f01
--- /dev/null
+++ b/src/nasm.c
@@ -0,0 +1,1252 @@
+#include <stdio.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdbool.h>
+
+#include "nasm.h"
+
+static void emit_const_expr(struct Expr* expr, FILE* out)
+{
+	switch (expr->kind)
+	{
+		case EXPR_PRIMARY:
+			fprintf(out, "%.*s", (int)expr->primary.token.length, expr->primary.token.start);
+			break;
+		case EXPR_UNARY:
+			fprintf(out, "%.*s", (int)expr->unary.op.length, expr->unary.op.start);
+			emit_const_expr(expr->unary.operand, out);
+			break;
+		case EXPR_BINARY:
+			emit_const_expr(expr->binary.left, out);
+			fprintf(out, " %.*s ", (int)expr->binary.op.length, expr->binary.op.start);
+			emit_const_expr(expr->binary.right, out);
+			break;
+		default:
+			break;
+	}
+}
+
+static void emit_consts(struct Program* program, FILE* out)
+{
+	for (size_t i = 0; i < program->const_count; i += 1)
+	{
+		struct ConstDecl decl = program->consts[i];
+		fprintf(out, "%%define %.*s (", (int)decl.name.length, decl.name.start);
+		emit_const_expr(decl.value, out);
+		fprintf(out, ")\n");
+	}
+}
+
+static void emit_data(struct Program* program, FILE* out)
+{
+	fprintf(out, "section .data\n");
+
+	for (size_t i = 0; i < program->data_count; i += 1)
+	{
+		struct DataDecl decl = program->data_decls[i];
+
+		// the value lexeme keeps its surrounding double quotes; NASM backtick
+		// strings interpret the same escapes, so re-wrap the inner content
+		fprintf(out, "%.*s: db `%.*s`\n",
+			(int)decl.name.length, decl.name.start,
+			(int)(decl.value.length - 2), decl.value.start + 1);
+		fprintf(out, ".len equ $ - %.*s\n",
+			(int)decl.name.length, decl.name.start);
+	}
+}
+
+static const char* assign_mnemonic(enum TokenType op)
+{
+	switch (op)
+	{
+		case TOKEN_EQUAL:      return "mov";
+		case TOKEN_PLUS_EQUAL:  return "add";
+		case TOKEN_MINUS_EQUAL: return "sub";
+		case TOKEN_STAR_EQUAL:  return "imul";
+		default:               return NULL;
+	}
+}
+
+struct FloatTable
+{
+	struct Token* items;
+	size_t count;
+	size_t capacity;
+};
+
+struct Emitter
+{
+	struct Program* program;
+	struct ProcDecl* proc;
+	struct FloatTable* floats;
+	FILE* out;
+	uint32_t label_id;
+};
+
+static bool is_float_register(struct Token token)
+{
+	if (token.length < 4 || memcmp(token.start, "xmm", 3) != 0)
+		return false;
+
+	for (size_t i = 3; i < token.length; i += 1)
+		if (token.start[i] < '0' || token.start[i] > '9')
+			return false;
+
+	return true;
+}
+
+static size_t float_index(const struct FloatTable* floats, struct Token literal)
+{
+	for (size_t i = 0; i < floats->count; i += 1)
+		if (floats->items[i].length == literal.length
+			&& memcmp(floats->items[i].start, literal.start, literal.length) == 0)
+			return i;
+
+	return floats->count;
+}
+
+static const char* sized_register(struct Token reg, enum StoreSize size);
+
+static struct Token resolve_token(struct Emitter* emitter, struct Token token)
+{
+	if (emitter->proc == NULL)
+		return token;
+
+	for (size_t i = 0; i < emitter->proc->param_count; i += 1)
+	{
+		struct Param param = emitter->proc->params[i];
+		if (param.name.length == token.length && memcmp(param.name.start, token.start, token.length) == 0)
+			return param.reg;
+	}
+
+	return token;
+}
+
+static struct Token text_token(const char* text)
+{
+	struct Token token;
+	token.type = TOKEN_IDENTIFIER;
+	token.start = text;
+	token.length = strlen(text);
+	token.line = 0;
+	return token;
+}
+
+// with the logical_registers extension, r1..r14 name the general-purpose
+// registers; rsp/rbp and the instruction pointer keep their dedicated names.
+static const char* logical_register_base(struct Token token)
+{
+	static const char* registers[] = {
+		"rax", "rbx", "rcx", "rdx", "rsi", "rdi",
+		"r8", "r9", "r10", "r11", "r12", "r13", "r14", "r15",
+	};
+
+	if (token.length < 2 || token.start[0] != 'r')
+		return NULL;
+
+	uint32_t index = 0;
+	for (size_t i = 1; i < token.length; i += 1)
+	{
+		char digit = token.start[i];
+		if (digit < '0' || digit > '9')
+			return NULL;
+		index = index * 10 + (uint32_t)(digit - '0');
+	}
+
+	if (index < 1 || index > sizeof(registers) / sizeof(registers[0]))
+		return NULL;
+
+	return registers[index - 1];
+}
+
+static struct Token resolve_register(struct Emitter* emitter, struct Token token)
+{
+	struct Token resolved = resolve_token(emitter, token);
+
+	if (emitter->program->config.logical_registers)
+	{
+		const char* base = logical_register_base(resolved);
+		if (base != NULL)
+			return text_token(base);
+	}
+
+	return resolved;
+}
+
+static uint64_t token_to_u64(struct Token token)
+{
+	if (token.length > 2 && token.start[0] == '0' && (token.start[1] == 'x' || token.start[1] == 'X'))
+	{
+		uint64_t value = 0;
+		for (size_t i = 2; i < token.length; i += 1)
+		{
+			char digit = token.start[i];
+			uint64_t nibble = digit <= '9' ? (uint64_t)(digit - '0')
+				: (uint64_t)((digit | 0x20) - 'a' + 10);
+			value = value * 16 + nibble;
+		}
+		return value;
+	}
+
+	if (token.length > 2 && token.start[0] == '0' && (token.start[1] == 'b' || token.start[1] == 'B'))
+	{
+		uint64_t value = 0;
+		for (size_t i = 2; i < token.length; i += 1)
+			value = value * 2 + (uint64_t)(token.start[i] - '0');
+		return value;
+	}
+
+	uint64_t value = 0;
+	for (size_t i = 0; i < token.length; i += 1)
+		value = value * 10 + (uint64_t)(token.start[i] - '0');
+
+	return value;
+}
+
+static bool fold_const(struct Program* program, struct Expr* expr, uint64_t* out);
+
+static bool buffer_offset(struct Emitter* emitter, struct Token name, uint64_t* out_offset)
+{
+	struct ProcDecl* proc = emitter->proc;
+	uint64_t cumulative = 0;
+	for (size_t i = 0; i < proc->body_count; i += 1)
+	{
+		struct Statement* statement = &proc->body[i];
+		if (statement->kind != STATEMENT_STACK)
+			continue;
+
+		uint64_t size = 0;
+		fold_const(emitter->program, statement->stack.size, &size);
+		cumulative += size;
+		if (statement->stack.name.length == name.length
+			&& memcmp(statement->stack.name.start, name.start, name.length) == 0)
+		{
+			*out_offset = cumulative;
+			return true;
+		}
+	}
+
+	return false;
+}
+
+static bool is_buffer_name(struct Emitter* emitter, struct Token token)
+{
+	uint64_t offset;
+	return emitter->proc != NULL && buffer_offset(emitter, token, &offset);
+}
+
+static enum StoreSize size_from_int(struct Token token)
+{
+	switch (token_to_u64(token))
+	{
+		case 8:  return STORE_SIZE_BYTE;
+		case 16: return STORE_SIZE_WORD;
+		case 32: return STORE_SIZE_DWORD;
+		case 64: return STORE_SIZE_QWORD;
+		default: return STORE_SIZE_NONE;
+	}
+}
+
+static bool tokens_equal(struct Token a, struct Token b)
+{
+	return a.length == b.length && memcmp(a.start, b.start, a.length) == 0;
+}
+
+static bool token_matches(struct Token token, const char* text)
+{
+	size_t length = strlen(text);
+	return token.length == length && memcmp(token.start, text, length) == 0;
+}
+
+static struct EnumDecl* find_enum(struct Program* program, struct Token name)
+{
+	for (size_t i = 0; i < program->enum_count; i += 1)
+		if (tokens_equal(program->enums[i].name, name))
+			return &program->enums[i];
+
+	return NULL;
+}
+
+static struct StructDecl* find_struct(struct Program* program, struct Token name)
+{
+	for (size_t i = 0; i < program->struct_count; i += 1)
+		if (tokens_equal(program->structs[i].name, name))
+			return &program->structs[i];
+
+	return NULL;
+}
+
+static uint64_t store_size_bytes(enum StoreSize size)
+{
+	switch (size)
+	{
+		case STORE_SIZE_BYTE:  return 1;
+		case STORE_SIZE_WORD:  return 2;
+		case STORE_SIZE_DWORD: return 4;
+		default:               return 8;
+	}
+}
+
+static uint64_t char_literal_value(struct Token token)
+{
+	if (token.length >= 4 && token.start[1] == '\\')
+	{
+		switch (token.start[2])
+		{
+			case 'n':  return 10;
+			case 't':  return 9;
+			case 'r':  return 13;
+			case '0':  return 0;
+			case '\\': return 92;
+			case '\'': return 39;
+			default:   return (unsigned char)token.start[2];
+		}
+	}
+
+	return (unsigned char)token.start[1];
+}
+
+static bool fold_member(struct Program* program, struct Expr* object, struct Token member, uint64_t* out)
+{
+	if (object->kind != EXPR_PRIMARY)
+		return false;
+	struct Token name = object->primary.token;
+
+	const struct EnumDecl* enumeration = find_enum(program, name);
+	if (enumeration != NULL)
+	{
+		for (size_t i = 0; i < enumeration->member_count; i += 1)
+			if (tokens_equal(enumeration->members[i], member))
+			{
+				*out = i;
+				return true;
+			}
+		return false;
+	}
+
+	const struct StructDecl* layout = find_struct(program, name);
+	if (layout != NULL)
+	{
+		uint64_t offset = 0;
+		for (size_t i = 0; i < layout->field_count; i += 1)
+		{
+			if (tokens_equal(layout->fields[i].name, member))
+			{
+				*out = offset;
+				return true;
+			}
+			offset += store_size_bytes(layout->fields[i].size);
+		}
+		if (token_matches(member, "size"))
+		{
+			*out = offset;
+			return true;
+		}
+	}
+
+	return false;
+}
+
+// evaluates a compile-time constant expression: integer/char literals, other
+// constants, enum values and struct offsets, and + - * / over them
+static bool fold_const(struct Program* program, struct Expr* expr, uint64_t* out)
+{
+	switch (expr->kind)
+	{
+		case EXPR_PRIMARY:
+		{
+			struct Token token = expr->primary.token;
+			if (token.type == TOKEN_INTEGER)
+			{
+				*out = token_to_u64(token);
+				return true;
+			}
+			if (token.type == TOKEN_CHAR)
+			{
+				*out = char_literal_value(token);
+				return true;
+			}
+			if (token.type == TOKEN_IDENTIFIER)
+				for (size_t i = 0; i < program->const_count; i += 1)
+					if (tokens_equal(program->consts[i].name, token))
+						return fold_const(program, program->consts[i].value, out);
+			return false;
+		}
+		case EXPR_UNARY:
+		{
+			uint64_t value;
+			if (!fold_const(program, expr->unary.operand, &value))
+				return false;
+			*out = 0 - value;
+			return true;
+		}
+		case EXPR_BINARY:
+		{
+			uint64_t left;
+			uint64_t right;
+			if (!fold_const(program, expr->binary.left, &left)
+				|| !fold_const(program, expr->binary.right, &right))
+				return false;
+
+			switch (expr->binary.op.type)
+			{
+				case TOKEN_PLUS:  *out = left + right; return true;
+				case TOKEN_MINUS: *out = left - right; return true;
+				case TOKEN_STAR:  *out = left * right; return true;
+				case TOKEN_SLASH: *out = right != 0 ? left / right : 0; return true;
+				default:          return false;
+			}
+		}
+		case EXPR_MEMBER:
+			return fold_member(program, expr->member.object, expr->member.member, out);
+		case EXPR_DEREF:
+			return false;
+	}
+
+	return false;
+}
+
+// an enum member folds to its 0-based index; a struct member folds to its byte
+// offset (or the total size for `.size`)
+static bool emit_named_member(struct Emitter* emitter, struct Token object, struct Token member)
+{
+	const struct EnumDecl* enumeration = find_enum(emitter->program, object);
+	if (enumeration != NULL)
+	{
+		for (size_t i = 0; i < enumeration->member_count; i += 1)
+			if (tokens_equal(enumeration->members[i], member))
+			{
+				fprintf(emitter->out, "%zu", i);
+				return true;
+			}
+	}
+
+	const struct StructDecl* layout = find_struct(emitter->program, object);
+	if (layout != NULL)
+	{
+		uint64_t offset = 0;
+		for (size_t i = 0; i < layout->field_count; i += 1)
+		{
+			if (tokens_equal(layout->fields[i].name, member))
+			{
+				fprintf(emitter->out, "%llu", (unsigned long long)offset);
+				return true;
+			}
+			offset += store_size_bytes(layout->fields[i].size);
+		}
+		if (token_matches(member, "size"))
+		{
+			fprintf(emitter->out, "%llu", (unsigned long long)offset);
+			return true;
+		}
+	}
+
+	return false;
+}
+
+static bool emit_operand(struct Emitter* emitter, struct Expr* expr)
+{
+	switch (expr->kind)
+	{
+		case EXPR_PRIMARY:
+		{
+			struct Token token = resolve_register(emitter, expr->primary.token);
+			fprintf(emitter->out, "%.*s", (int)token.length, token.start);
+			return true;
+		}
+		case EXPR_MEMBER:
+		{
+			// a register size suffix: r1.64 -> rax, r1.8 -> al
+			if (expr->member.member.type == TOKEN_INTEGER &&
+				expr->member.object->kind == EXPR_PRIMARY)
+			{
+				enum StoreSize size = size_from_int(expr->member.member);
+				struct Token base = resolve_register(emitter, expr->member.object->primary.token);
+				const char* sized = sized_register(base, size);
+				if (sized != NULL)
+					fprintf(emitter->out, "%s", sized);
+				else
+					fprintf(emitter->out, "%.*s", (int)base.length, base.start);
+				return true;
+			}
+
+			// enum value or struct offset
+			if (expr->member.object->kind == EXPR_PRIMARY
+				&& emit_named_member(emitter, expr->member.object->primary.token, expr->member.member))
+				return true;
+
+			if (!emit_operand(emitter, expr->member.object))
+				return false;
+			fprintf(emitter->out, ".%.*s", (int)expr->member.member.length, expr->member.member.start);
+			return true;
+		}
+		case EXPR_UNARY:
+		{
+			uint64_t value;
+			if (!fold_const(emitter->program, expr, &value))
+				return false;
+			fprintf(emitter->out, "%lld", (long long)value);
+			return true;
+		}
+		case EXPR_BINARY:
+		case EXPR_DEREF:
+			return false;
+	}
+
+	return false;
+}
+
+// idiv divides rdx:rax by its operand and leaves the quotient in rax, so a
+// division computes `dst = dst / divisor` through rax (clobbering rax and rdx).
+static void emit_division(struct Emitter* emitter, const char* dst, struct Expr* divisor)
+{
+	bool dst_is_rax = strcmp(dst, "rax") == 0;
+
+	if (!dst_is_rax)
+		fprintf(emitter->out, "\tmov rax, %s\n", dst);
+	fprintf(emitter->out, "\tcqo\n");
+	fprintf(emitter->out, "\tidiv ");
+	emit_operand(emitter, divisor);
+	fprintf(emitter->out, "\n");
+	if (!dst_is_rax)
+		fprintf(emitter->out, "\tmov %s, rax\n", dst);
+}
+
+// idiv leaves the remainder in rdx, so a modulo takes its result from there
+static void emit_modulo(struct Emitter* emitter, const char* dst, struct Expr* divisor)
+{
+	if (strcmp(dst, "rax") != 0)
+		fprintf(emitter->out, "\tmov rax, %s\n", dst);
+	fprintf(emitter->out, "\tcqo\n");
+	fprintf(emitter->out, "\tidiv ");
+	emit_operand(emitter, divisor);
+	fprintf(emitter->out, "\n");
+	if (strcmp(dst, "rdx") != 0)
+		fprintf(emitter->out, "\tmov %s, rdx\n", dst);
+}
+
+static void emit_divide(struct Emitter* emitter, struct AssignStatement* assign)
+{
+	if (assign->target_deref)
+	{
+		fprintf(emitter->out, "\t; TODO: unsupported division\n");
+		return;
+	}
+
+	struct Token target = resolve_register(emitter, assign->target);
+	char dst[32];
+	snprintf(dst, sizeof(dst), "%.*s", (int)target.length, target.start);
+
+	if (assign->op.type == TOKEN_PERCENT_EQUAL)
+		emit_modulo(emitter, dst, assign->value);
+	else
+		emit_division(emitter, dst, assign->value);
+}
+
+// an expression can be evaluated into a register when it is a single term
+// (primary or member), or a left-associative chain of binary operators whose
+// right operands are plain operands (never a buffer or a nested binary)
+static bool expr_supported(struct Emitter* emitter, struct Expr* expr)
+{
+	switch (expr->kind)
+	{
+		case EXPR_PRIMARY:
+		case EXPR_MEMBER:
+		case EXPR_DEREF:
+			return true;
+		case EXPR_UNARY:
+		{
+			uint64_t value;
+			return fold_const(emitter->program, expr, &value);
+		}
+		case EXPR_BINARY:
+			if (expr->binary.right->kind != EXPR_PRIMARY &&
+				expr->binary.right->kind != EXPR_MEMBER &&
+				expr->binary.right->kind != EXPR_UNARY)
+				return false;
+			if (expr->binary.right->kind == EXPR_UNARY)
+			{
+				uint64_t value;
+				if (!fold_const(emitter->program, expr->binary.right, &value))
+					return false;
+			}
+			if (expr->binary.right->kind == EXPR_PRIMARY &&
+				is_buffer_name(emitter, expr->binary.right->primary.token))
+				return false;
+			return expr_supported(emitter, expr->binary.left);
+	}
+
+	return false;
+}
+
+// dst = [address], extending narrower loads into the full register. Unsigned
+// loads zero-extend (movzx / a 32-bit mov); signed loads sign-extend (movsx,
+// or movsxd for a dword).
+static void emit_load(struct Emitter* emitter, const char* dst, struct DerefExpr* deref)
+{
+	FILE* out = emitter->out;
+	if (deref->is_signed)
+	{
+		switch (deref->size)
+		{
+			case STORE_SIZE_BYTE:
+				fprintf(out, "\tmovsx %s, byte [", dst);
+				break;
+			case STORE_SIZE_WORD:
+				fprintf(out, "\tmovsx %s, word [", dst);
+				break;
+			case STORE_SIZE_DWORD:
+				fprintf(out, "\tmovsxd %s, dword [", dst);
+				break;
+			default:
+				fprintf(out, "\tmov %s, [", dst);
+				break;
+		}
+
+		emit_operand(emitter, deref->address);
+		fprintf(out, "]\n");
+		return;
+	}
+
+	switch (deref->size)
+	{
+		case STORE_SIZE_BYTE:
+			fprintf(out, "\tmovzx %s, byte [", dst);
+			break;
+		case STORE_SIZE_WORD:
+			fprintf(out, "\tmovzx %s, word [", dst);
+			break;
+		case STORE_SIZE_DWORD:
+		{
+			const char* dword = sized_register(text_token(dst), STORE_SIZE_DWORD);
+			fprintf(out, "\tmov %s, [", dword != NULL ? dword : dst);
+			break;
+		}
+		default:
+			fprintf(out, "\tmov %s, [", dst);
+			break;
+	}
+
+	emit_operand(emitter, deref->address);
+	fprintf(out, "]\n");
+}
+
+static void emit_expr_into(struct Emitter* emitter, const char* dst, struct Expr* expr)
+{
+	if (expr->kind == EXPR_DEREF)
+	{
+		emit_load(emitter, dst, &expr->deref);
+		return;
+	}
+
+	if (expr->kind == EXPR_BINARY)
+	{
+		emit_expr_into(emitter, dst, expr->binary.left);
+
+		if (expr->binary.op.type == TOKEN_SLASH)
+		{
+			emit_division(emitter, dst, expr->binary.right);
+			return;
+		}
+		if (expr->binary.op.type == TOKEN_PERCENT)
+		{
+			emit_modulo(emitter, dst, expr->binary.right);
+			return;
+		}
+
+		const char* mnemonic =
+			expr->binary.op.type == TOKEN_PLUS ? "add" :
+			expr->binary.op.type == TOKEN_MINUS ? "sub" : "imul";
+		fprintf(emitter->out, "\t%s %s, ", mnemonic, dst);
+		emit_operand(emitter, expr->binary.right);
+		fprintf(emitter->out, "\n");
+		return;
+	}
+
+	if (expr->kind == EXPR_PRIMARY && is_buffer_name(emitter, expr->primary.token))
+	{
+		uint64_t offset;
+		buffer_offset(emitter, expr->primary.token, &offset);
+		fprintf(emitter->out, "\tlea %s, [rbp - %llu]\n", dst, (unsigned long long)offset);
+		return;
+	}
+
+	fprintf(emitter->out, "\tmov %s, ", dst);
+	emit_operand(emitter, expr);
+	fprintf(emitter->out, "\n");
+}
+
+static const char* store_size_keyword(enum StoreSize size)
+{
+	switch (size)
+	{
+		case STORE_SIZE_BYTE:  return "byte ";
+		case STORE_SIZE_WORD:  return "word ";
+		case STORE_SIZE_DWORD: return "dword ";
+		case STORE_SIZE_QWORD: return "qword ";
+		default:               return "";
+	}
+}
+
+// maps a full 64-bit register to its byte/word/dword sub-register for a sized
+// store, so `^byte rsi = rdx` writes `dl` rather than the whole register.
+// returns NULL when the token is not a full register, or no resizing applies.
+static const char* sized_register(struct Token reg, enum StoreSize size)
+{
+	if (size == STORE_SIZE_NONE || size == STORE_SIZE_QWORD)
+		return NULL;
+
+	static const struct RegisterSizes
+	{
+		const char* quad;
+		const char* dword;
+		const char* word;
+		const char* byte;
+	} registers[] =
+	{
+		{ "rax", "eax",  "ax",   "al"   },
+		{ "rbx", "ebx",  "bx",   "bl"   },
+		{ "rcx", "ecx",  "cx",   "cl"   },
+		{ "rdx", "edx",  "dx",   "dl"   },
+		{ "rsi", "esi",  "si",   "sil"  },
+		{ "rdi", "edi",  "di",   "dil"  },
+		{ "rbp", "ebp",  "bp",   "bpl"  },
+		{ "rsp", "esp",  "sp",   "spl"  },
+		{ "r8",  "r8d",  "r8w",  "r8b"  },
+		{ "r9",  "r9d",  "r9w",  "r9b"  },
+		{ "r10", "r10d", "r10w", "r10b" },
+		{ "r11", "r11d", "r11w", "r11b" },
+		{ "r12", "r12d", "r12w", "r12b" },
+		{ "r13", "r13d", "r13w", "r13b" },
+		{ "r14", "r14d", "r14w", "r14b" },
+		{ "r15", "r15d", "r15w", "r15b" },
+	};
+
+	for (size_t i = 0; i < sizeof(registers) / sizeof(registers[0]); i += 1)
+	{
+		const struct RegisterSizes* entry = &registers[i];
+		size_t length = strlen(entry->quad);
+		if (reg.length != length || memcmp(reg.start, entry->quad, length) != 0)
+			continue;
+
+		switch (size)
+		{
+			case STORE_SIZE_DWORD: return entry->dword;
+			case STORE_SIZE_WORD:  return entry->word;
+			case STORE_SIZE_BYTE:  return entry->byte;
+			default:               return NULL;
+		}
+	}
+
+	return NULL;
+}
+
+static const char* float_mnemonic(enum TokenType op)
+{
+	switch (op)
+	{
+		case TOKEN_EQUAL:       return "movsd";
+		case TOKEN_PLUS_EQUAL:  return "addsd";
+		case TOKEN_MINUS_EQUAL: return "subsd";
+		case TOKEN_STAR_EQUAL:  return "mulsd";
+		case TOKEN_SLASH_EQUAL: return "divsd";
+		default:                return NULL;
+	}
+}
+
+static bool value_is_float(struct Emitter* emitter, const struct Expr* expr)
+{
+	if (expr->kind != EXPR_PRIMARY)
+		return false;
+	if (expr->primary.token.type == TOKEN_FLOAT)
+		return true;
+
+	return is_float_register(resolve_register(emitter, expr->primary.token));
+}
+
+// floating point: xmm moves and arithmetic, conversions to/from general-purpose
+// registers, and float literals loaded from their .data slot
+static bool emit_float_assign(struct Emitter* emitter, struct AssignStatement* assign,
+	struct Token target, bool target_float)
+{
+	struct Expr* value = assign->value;
+
+	// float store: ^ptr = xmm  ->  movsd [ptr], xmm
+	if (assign->target_deref)
+	{
+		if (assign->op.type != TOKEN_EQUAL || value->kind != EXPR_PRIMARY)
+			return false;
+		struct Token source = resolve_register(emitter, value->primary.token);
+		if (!is_float_register(source))
+			return false;
+		fprintf(emitter->out, "\tmovsd [%.*s], %.*s\n",
+			(int)target.length, target.start, (int)source.length, source.start);
+		return true;
+	}
+
+	// float load: xmm = ^ptr  ->  movsd xmm, [ptr]
+	if (value->kind == EXPR_DEREF)
+	{
+		if (!target_float || assign->op.type != TOKEN_EQUAL)
+			return false;
+		fprintf(emitter->out, "\tmovsd %.*s, [", (int)target.length, target.start);
+		emit_operand(emitter, value->deref.address);
+		fprintf(emitter->out, "]\n");
+		return true;
+	}
+
+	if (value->kind == EXPR_PRIMARY && value->primary.token.type == TOKEN_FLOAT)
+	{
+		if (!target_float || assign->op.type != TOKEN_EQUAL)
+			return false;
+		size_t index = float_index(emitter->floats, value->primary.token);
+		fprintf(emitter->out, "\tmovsd %.*s, [__float%zu]\n",
+			(int)target.length, target.start, index);
+		return true;
+	}
+
+	if (value->kind != EXPR_PRIMARY)
+		return false;
+
+	struct Token source = resolve_register(emitter, value->primary.token);
+	bool source_float = is_float_register(source);
+
+	if (target_float && source_float)
+	{
+		const char* mnemonic = float_mnemonic(assign->op.type);
+		if (mnemonic == NULL)
+			return false;
+		fprintf(emitter->out, "\t%s %.*s, %.*s\n", mnemonic,
+			(int)target.length, target.start, (int)source.length, source.start);
+		return true;
+	}
+
+	if (assign->op.type != TOKEN_EQUAL)
+		return false;
+
+	if (target_float)
+		fprintf(emitter->out, "\tcvtsi2sd %.*s, %.*s\n",
+			(int)target.length, target.start, (int)source.length, source.start);
+	else
+		fprintf(emitter->out, "\tcvttsd2si %.*s, %.*s\n",
+			(int)target.length, target.start, (int)source.length, source.start);
+	return true;
+}
+
+static void emit_assign(struct Emitter* emitter, struct AssignStatement* assign)
+{
+	struct Token float_target = resolve_register(emitter, assign->target);
+	if (is_float_register(float_target) || value_is_float(emitter, assign->value))
+	{
+		if (!emit_float_assign(emitter, assign, float_target, is_float_register(float_target)))
+			fprintf(emitter->out, "\t; TODO: unsupported float assignment\n");
+		return;
+	}
+
+	if (assign->op.type == TOKEN_SLASH_EQUAL || assign->op.type == TOKEN_PERCENT_EQUAL)
+	{
+		emit_divide(emitter, assign);
+		return;
+	}
+
+	struct Token target = resolve_register(emitter, assign->target);
+
+	if (assign->op.type == TOKEN_EQUAL && !assign->target_deref)
+	{
+		if (!expr_supported(emitter, assign->value))
+		{
+			fprintf(emitter->out, "\t; TODO: unsupported assignment\n");
+			return;
+		}
+
+		char dst[32];
+		snprintf(dst, sizeof(dst), "%.*s", (int)target.length, target.start);
+		emit_expr_into(emitter, dst, assign->value);
+		return;
+	}
+
+	// deref store or compound assignment: needs a plain operand, not a buffer or binary
+	const char* mnemonic = assign_mnemonic(assign->op.type);
+	bool value_is_buffer = assign->value->kind == EXPR_PRIMARY 
+		                && is_buffer_name(emitter, assign->value->primary.token);
+	if (mnemonic == NULL || assign->value->kind == EXPR_BINARY
+		|| assign->value->kind == EXPR_DEREF || value_is_buffer)
+	{
+		fprintf(emitter->out, "\t; TODO: unsupported assignment\n");
+		return;
+	}
+
+	// adding or subtracting a constant zero (e.g. a struct field at offset 0) is a no-op
+	uint64_t folded;
+	if (!assign->target_deref
+		&& (assign->op.type == TOKEN_PLUS_EQUAL || assign->op.type == TOKEN_MINUS_EQUAL)
+		&& fold_const(emitter->program, assign->value, &folded) && folded == 0)
+		return;
+
+	if (assign->target_deref)
+	{
+		fprintf(emitter->out, "\t%s %s[%.*s], ", mnemonic,
+			store_size_keyword(assign->store_size), (int)target.length, target.start);
+
+		const char* sized = NULL;
+		if (assign->value->kind == EXPR_PRIMARY)
+		{
+			struct Token value = resolve_register(emitter, assign->value->primary.token);
+			sized = sized_register(value, assign->store_size);
+			if (sized != NULL)
+				fprintf(emitter->out, "%s", sized);
+		}
+
+		if (sized == NULL)
+			emit_operand(emitter, assign->value);
+	}
+	else
+	{
+		fprintf(emitter->out, "\t%s %.*s, ", mnemonic, (int)target.length, target.start);
+		emit_operand(emitter, assign->value);
+	}
+
+	fprintf(emitter->out, "\n");
+}
+
+static const char* jump_if_false(enum TokenType comparison)
+{
+	switch (comparison)
+	{
+		case TOKEN_EQUAL_EQUAL:   return "jne";
+		case TOKEN_BANG_EQUAL:    return "je";
+		case TOKEN_LESS:          return "jge";
+		case TOKEN_LESS_EQUAL:    return "jg";
+		case TOKEN_GREATER:       return "jle";
+		case TOKEN_GREATER_EQUAL: return "jl";
+		default:                  return NULL;
+	}
+}
+
+static struct ProcDecl* find_proc(struct Program* program, struct Token name)
+{
+	for (size_t i = 0; i < program->proc_count; i += 1)
+	{
+		struct ProcDecl* proc = &program->procs[i];
+		if (proc->name.length == name.length && memcmp(proc->name.start, name.start, name.length) == 0)
+			return proc;
+	}
+
+	return NULL;
+}
+
+static void emit_call(struct Emitter* emitter, struct CallStatement* call)
+{
+	const struct ProcDecl* callee = find_proc(emitter->program, call->name);
+	if (callee == NULL || callee->param_count != call->arg_count)
+	{
+		fprintf(emitter->out, "\t; TODO: unsupported call\n");
+		return;
+	}
+
+	for (size_t i = 0; i < call->arg_count; i += 1)
+	{
+		if (call->args[i]->kind == EXPR_BINARY || call->args[i]->kind == EXPR_DEREF)
+		{
+			fprintf(emitter->out, "\t; TODO: unsupported call argument\n");
+			continue;
+		}
+
+		struct Token reg = resolve_register(emitter, callee->params[i].reg);
+		fprintf(emitter->out, "\tmov %.*s, ", (int)reg.length, reg.start);
+		emit_operand(emitter, call->args[i]);
+		fprintf(emitter->out, "\n");
+	}
+
+	fprintf(emitter->out, "\tcall %.*s\n", (int)call->name.length, call->name.start);
+}
+
+static void emit_statement(struct Emitter* emitter, struct Statement* statement);
+
+static void emit_block(struct Emitter* emitter, struct Statement* body, size_t count)
+{
+	for (size_t i = 0; i < count; i += 1)
+		emit_statement(emitter, &body[i]);
+}
+
+// ucomisd sets the flags like an unsigned compare, so float branches use the
+// unsigned jump family (ja/jae/jb/jbe) rather than the signed one
+static const char* float_jump_if_false(enum TokenType comparison)
+{
+	switch (comparison)
+	{
+		case TOKEN_EQUAL_EQUAL:   return "jne";
+		case TOKEN_BANG_EQUAL:    return "je";
+		case TOKEN_LESS:          return "jae";
+		case TOKEN_LESS_EQUAL:    return "ja";
+		case TOKEN_GREATER:       return "jbe";
+		case TOKEN_GREATER_EQUAL: return "jb";
+		default:                  return NULL;
+	}
+}
+
+static void emit_float_operand(struct Emitter* emitter, const struct Expr* expr)
+{
+	if (expr->kind == EXPR_PRIMARY && expr->primary.token.type == TOKEN_FLOAT)
+	{
+		fprintf(emitter->out, "[__float%zu]", float_index(emitter->floats, expr->primary.token));
+		return;
+	}
+
+	struct Token token = resolve_register(emitter, expr->primary.token);
+	fprintf(emitter->out, "%.*s", (int)token.length, token.start);
+}
+
+static void emit_if(struct Emitter* emitter, struct IfStatement* branch)
+{
+	bool is_float = value_is_float(emitter, branch->left) || value_is_float(emitter, branch->right);
+	bool has_else = branch->else_count > 0;
+
+	uint32_t id = emitter->label_id;
+	emitter->label_id += 1;
+
+	const char* target = has_else ? ".if_else_" : ".if_end_";
+
+	if (is_float)
+	{
+		const char* jump = float_jump_if_false(branch->comparison.type);
+		bool left_reg = branch->left->kind == EXPR_PRIMARY
+			&& is_float_register(resolve_register(emitter, branch->left->primary.token));
+		if (jump == NULL || !left_reg || !value_is_float(emitter, branch->right))
+		{
+			fprintf(emitter->out, "\t; TODO: unsupported if\n");
+			return;
+		}
+
+		fprintf(emitter->out, "\tucomisd ");
+		emit_float_operand(emitter, branch->left);
+		fprintf(emitter->out, ", ");
+		emit_float_operand(emitter, branch->right);
+		fprintf(emitter->out, "\n\t%s %s%u\n", jump, target, id);
+	}
+	else
+	{
+		const char* jump = jump_if_false(branch->comparison.type);
+		if (jump == NULL
+			|| branch->left->kind == EXPR_BINARY || branch->left->kind == EXPR_DEREF
+			|| branch->right->kind == EXPR_BINARY || branch->right->kind == EXPR_DEREF)
+		{
+			fprintf(emitter->out, "\t; TODO: unsupported if\n");
+			return;
+		}
+
+		fprintf(emitter->out, "\tcmp ");
+		emit_operand(emitter, branch->left);
+		fprintf(emitter->out, ", ");
+		emit_operand(emitter, branch->right);
+		fprintf(emitter->out, "\n\t%s %s%u\n", jump, target, id);
+	}
+
+	emit_block(emitter, branch->body, branch->body_count);
+
+	if (has_else)
+	{
+		fprintf(emitter->out, "\tjmp .if_end_%u\n", id);
+		fprintf(emitter->out, ".if_else_%u:\n", id);
+		emit_block(emitter, branch->else_body, branch->else_count);
+	}
+
+	fprintf(emitter->out, ".if_end_%u:\n", id);
+}
+
+static void emit_statement(struct Emitter* emitter, struct Statement* statement)
+{
+	FILE* out = emitter->out;
+	switch (statement->kind)
+	{
+		case STATEMENT_ASSIGN:
+			emit_assign(emitter, &statement->assign);
+			break;
+		case STATEMENT_LABEL:
+			fprintf(out, "%.*s:\n", (int)statement->label.name.length, statement->label.name.start);
+			break;
+		case STATEMENT_GOTO:
+			fprintf(out, "\tjmp %.*s\n", (int)statement->jump.label.length, statement->jump.label.start);
+			break;
+		case STATEMENT_SYSCALL:
+			fprintf(out, "\tsyscall\n");
+			break;
+		case STATEMENT_IF:
+			emit_if(emitter, &statement->branch);
+			break;
+		case STATEMENT_CALL:
+			emit_call(emitter, &statement->call);
+			break;
+		case STATEMENT_STACK:
+			break;
+		default:
+			fprintf(out, "\t; TODO: unsupported statement\n");
+			break;
+	}
+}
+
+static uint64_t proc_stack_size(struct Program* program, struct ProcDecl* proc)
+{
+	uint64_t total = 0;
+	for (size_t i = 0; i < proc->body_count; i += 1)
+	{
+		struct Statement* statement = &proc->body[i];
+		if (statement->kind == STATEMENT_STACK)
+		{
+			uint64_t size = 0;
+			fold_const(program, statement->stack.size, &size);
+			total += size;
+		}
+	}
+
+	if (total % 16 != 0)
+		total += 16 - (total % 16);
+
+	return total;
+}
+
+static void collect_float(struct FloatTable* floats, struct Token token)
+{
+	if (token.type != TOKEN_FLOAT || float_index(floats, token) != floats->count)
+		return;
+
+	if (floats->count == floats->capacity)
+	{
+		size_t capacity = floats->capacity < 8 ? 8 : floats->capacity * 2;
+		floats->items = realloc(floats->items, capacity * sizeof(struct Token));
+		floats->capacity = capacity;
+	}
+
+	floats->items[floats->count] = token;
+	floats->count += 1;
+}
+
+static void collect_floats_expr(struct FloatTable* floats, struct Expr* expr)
+{
+	switch (expr->kind)
+	{
+		case EXPR_PRIMARY:
+			collect_float(floats, expr->primary.token);
+			break;
+		case EXPR_UNARY:
+			collect_floats_expr(floats, expr->unary.operand);
+			break;
+		case EXPR_BINARY:
+			collect_floats_expr(floats, expr->binary.left);
+			collect_floats_expr(floats, expr->binary.right);
+			break;
+		case EXPR_MEMBER:
+			collect_floats_expr(floats, expr->member.object);
+			break;
+		case EXPR_DEREF:
+			collect_floats_expr(floats, expr->deref.address);
+			break;
+	}
+}
+
+static void collect_floats_statement(struct FloatTable* floats, struct Statement* statement)
+{
+	switch (statement->kind)
+	{
+		case STATEMENT_ASSIGN:
+			collect_floats_expr(floats, statement->assign.value);
+			break;
+		case STATEMENT_IF:
+			collect_floats_expr(floats, statement->branch.left);
+			collect_floats_expr(floats, statement->branch.right);
+			for (size_t i = 0; i < statement->branch.body_count; i += 1)
+				collect_floats_statement(floats, &statement->branch.body[i]);
+			for (size_t i = 0; i < statement->branch.else_count; i += 1)
+				collect_floats_statement(floats, &statement->branch.else_body[i]);
+			break;
+		case STATEMENT_CALL:
+			for (size_t i = 0; i < statement->call.arg_count; i += 1)
+				collect_floats_expr(floats, statement->call.args[i]);
+			break;
+		default:
+			break;
+	}
+}
+
+static struct FloatTable collect_floats(struct Program* program)
+{
+	struct FloatTable floats = { NULL, 0, 0 };
+	for (size_t i = 0; i < program->proc_count; i += 1)
+		for (size_t j = 0; j < program->procs[i].body_count; j += 1)
+			collect_floats_statement(&floats, &program->procs[i].body[j]);
+
+	return floats;
+}
+
+static void emit_float_data(const struct FloatTable* floats, FILE* out)
+{
+	for (size_t i = 0; i < floats->count; i += 1)
+		fprintf(out, "__float%zu: dq %.*s\n", i,
+			(int)floats->items[i].length, floats->items[i].start);
+}
+
+static void emit_proc(struct Program* program, struct FloatTable* floats, struct ProcDecl* proc, FILE* out)
+{
+	struct Emitter emitter;
+	emitter.program = program;
+	emitter.proc = proc;
+	emitter.floats = floats;
+	emitter.out = out;
+	emitter.label_id = 0;
+
+	struct Config config = program->config;
+	bool is_entry = config.has_entry
+		&& proc->name.length == config.entry.length
+		&& memcmp(proc->name.start, config.entry.start, proc->name.length) == 0;
+
+	fprintf(out, "%.*s:\n", (int)proc->name.length, proc->name.start);
+
+	uint64_t stack_size = proc_stack_size(program, proc);
+	if (stack_size > 0)
+	{
+		fprintf(out, "\tpush rbp\n");
+		fprintf(out, "\tmov rbp, rsp\n");
+		fprintf(out, "\tsub rsp, %llu\n", (unsigned long long)stack_size);
+	}
+
+	for (size_t i = 0; i < proc->body_count; i += 1)
+		emit_statement(&emitter, &proc->body[i]);
+
+	if (!is_entry)
+	{
+		if (stack_size > 0)
+			fprintf(out, "\tleave\n");
+		fprintf(out, "\tret\n");
+	}
+}
+
+void generate_nasm(struct Program* program, FILE* out)
+{
+	struct FloatTable floats = collect_floats(program);
+
+	fprintf(out, "bits %u\n\n", program->config.bits);
+
+	if (program->const_count > 0)
+	{
+		emit_consts(program, out);
+		fprintf(out, "\n");
+	}
+
+	emit_data(program, out);
+	emit_float_data(&floats, out);
+	fprintf(out, "\n");
+
+	fprintf(out, "section .text\n");
+	if (program->config.has_entry)
+		fprintf(out, "global %.*s\n", (int)program->config.entry.length, program->config.entry.start);
+
+	for (size_t i = 0; i < program->proc_count; i += 1)
+	{
+		fprintf(out, "\n");
+		emit_proc(program, &floats, &program->procs[i], out);
+	}
+
+	free(floats.items);
+}