Add ASSERT macro + fix label substractions banks + add . for current address

3 files changed, 49 insertions, 2 deletions

diff --git a/instructions.go b/instructions.go
index 80bedec..ff87e44 100644
--- a/instructions.go
+++ b/instructions.go
@@ -13,6 +13,7 @@ type InstructionParams struct {
 	Wildcard         bool
 	MacroForbidden   bool
 	LabelsBeforeOnly bool
+	SkipFirstPass    bool
 }
 
 type InstructionSet map[string][]InstructionParams
@@ -525,6 +526,10 @@ func (set InstructionSet) Parse(
 	var rejectedErrors error
 instruction_param_loop:
 	for _, instrParam := range instruction {
+		if instrParam.SkipFirstPass && isFirstPass {
+			return []byte{}, nil
+		}
+
 		if !instrParam.Wildcard && len(instrParam.Types) != len(params) {
 			continue
 		}
diff --git a/macros.go b/macros.go
index 2324a14..44b72a2 100644
--- a/macros.go
+++ b/macros.go
@@ -43,6 +43,31 @@ func NewInstructionSetMacros() InstructionSet {
 		},
 	}
 
+	result[".ASSERT"] = []InstructionParams{
+		{
+			Types: []ParamType{Raw8, Raw8},
+			Assembler: func(currentAddress uint32, args []uint32) ([]byte, error) {
+				if args[0] != args[1] {
+					return nil, fmt.Errorf("ASSERTION FAILED, %v != %v", args[0], args[1])
+				}
+				return []byte{}, nil
+			},
+			MacroForbidden: false,
+			SkipFirstPass:  true,
+		},
+		{
+			Types: []ParamType{Raw16, Raw16},
+			Assembler: func(currentAddress uint32, args []uint32) ([]byte, error) {
+				if args[0] != args[1] {
+					return nil, fmt.Errorf("ASSERTION FAILED, %v != %v", args[0], args[1])
+				}
+				return []byte{}, nil
+			},
+			MacroForbidden: false,
+			SkipFirstPass:  true,
+		},
+	}
+
 	result[".DB"] = []InstructionParams{
 		{
 			Types: []ParamType{Raw8},
diff --git a/parameters.go b/parameters.go
index 5dffc1c..b812fef 100644
--- a/parameters.go
+++ b/parameters.go
@@ -234,17 +234,29 @@ func Raw16(
 	if strings.Contains(param, "-") {
 		spl := strings.Split(param, "-")
 
-		v, err := Raw16(labels, lastAbsoluteLabel, defs, currentAddress, spl[0])
+		v, err := ROMAddress(labels, lastAbsoluteLabel, defs, currentAddress, spl[0])
 		if err != nil {
 			return 0, err
 		}
+
+		bank := v / 0x4000
 		result := v
 
 		for _, arg := range spl[1:] {
-			v, err := Raw16(labels, lastAbsoluteLabel, defs, currentAddress, arg)
+			v, err := ROMAddress(labels, lastAbsoluteLabel, defs, currentAddress, arg)
 			if err != nil {
 				return 0, err
 			}
+			otherBank := v / 0x4000
+			if bank != otherBank {
+				return 0, fmt.Errorf(
+					"Cannot get distance between rom addresses in different banks (%s is in bank %v, %s is in bank %v)",
+					spl[0],
+					bank,
+					arg,
+					otherBank,
+				)
+			}
 			result -= v
 		}
 
@@ -293,6 +305,7 @@ func Raw16(
 		currentBank := currentAddress / 0x4000
 		romAddrBank := romAddr / 0x4000
 
+		// TODO: Forbidding calls from other banks to bank 0
 		if romAddrBank == 0 {
 			return romAddr, nil
 		}
@@ -422,6 +435,10 @@ func ROMAddress(
 	currentAddress uint32,
 	param string,
 ) (uint32, error) {
+	if param == "." {
+		return currentAddress, nil
+	}
+
 	if strings.HasPrefix(param, "=") {
 		labelWithoutOffset, offset, err := parseOffset(param[1:])
 		if err != nil {