all: start removing most dependencies on unsafe

unsafe was primarily used to get the cell size in bits. It's now a const.

asm/parser.go

@@ -23,7 +23,6 @@ import (
 	"strings"
 	"text/scanner"
 	"unicode"
-	"unsafe"
 
 	"github.com/db47h/ngaro/vm"
 )
@@ -215,7 +214,7 @@ func (p *parser) scan() (tok rune, s string, v int) {
 	}
 
 	// check int
-	n, err := strconv.ParseInt(s, 0, 8*int(unsafe.Sizeof(vm.Cell(0))))
+	n, err := strconv.ParseInt(s, 0, vm.CellBits)
 	if err == nil {
 		return scanner.Int, s, int(n)
 	}

cmd/retro/main.go

@@ -23,7 +23,6 @@ import (
 	"io"
 	"os"
 	"strconv"
-	"unsafe"
 
 	"github.com/db47h/ngaro/vm"
 	"github.com/pkg/errors"
@@ -59,7 +58,7 @@ var (
 	debug       bool
 	dump        bool
 	outFileName string
-	srcCellSz   = cellSizeBits(unsafe.Sizeof(vm.Cell(0)) * 8)
+	srcCellSz   = cellSizeBits(vm.CellBits)
 	dstCellSz   = srcCellSz
 )
 

vm/io.go

@@ -281,7 +281,7 @@ func (i *Instance) Wait(v, port Cell) error {
 					i.Ports[5] = 0
 				}
 			case -13:
-				i.Ports[5] = Cell(unsafe.Sizeof(Cell(0)) * 8)
+				i.Ports[5] = CellBits
 			case -14:
 				v = 0x01000000
 				i.Ports[5] = Cell(*(*int8)(unsafe.Pointer(&v)))

vm/io_test.go

@@ -108,7 +108,7 @@ func Test_io_Caps(t *testing.T) {
 	}
 	assertEqualI(t, "io_Caps port 8", -1, int(i.Pop()))
 	assertEqualI(t, "io_Caps endian", 0, int(i.Pop()))
-	assertEqualI(t, "io_Caps Cell bits", 8*int(unsafe.Sizeof(vm.Cell(0))), int(i.Pop()))
+	assertEqualI(t, "io_Caps Cell bits", 8*int(unsafe.Sizeof(vm.Cell(0))), int(i.Pop())) // do not use vm.CellBits, just to check
 	assertEqualI(t, "io_Caps rstack", 3, int(i.Pop()))
 	assertEqualI(t, "io_Caps rstack", 1, int(i.Pop()))
 }
@@ -199,7 +199,7 @@ func TestLoad(t *testing.T) {
 		t.Fatalf("Expected -1, got %d", mem[0])
 	}
 	// force failure if vm.Cell is 32 bits
-	if unsafe.Sizeof(vm.Cell(0)) == 4 {
+	if vm.CellBits == 32 {
 		_, _, err = vm.Load(fn, 0, 64)
 		exp := "load error: 64 bits value 8589934591 at memory location 0 too large"
 		if err == nil || err.Error() != exp {
@@ -250,7 +250,7 @@ func TestSave_32(t *testing.T) {
 		return vm.Save(fileName, mem, 32)
 	}
 	// force failure if vm.Cell is 64 bits
-	if unsafe.Sizeof(vm.Cell(0)) == 8 {
+	if vm.CellBits == 64 {
 		x := int64(1)
 		img[2] = vm.Cell(x << 32)
 		_, err := runImage(img, d, vm.SaveMemImage(sf))

vm/mem.go

@@ -21,7 +21,6 @@ import (
 	"encoding/binary"
 	"io"
 	"os"
-	"unsafe"
 
 	"github.com/pkg/errors"
 )
@@ -79,7 +78,7 @@ func load64(mem []Cell, r io.Reader, fileCells int) error {
 func Load(fileName string, minSize, cellBits int) (mem []Cell, fileCells int, err error) {
 	switch cellBits {
 	case 0:
-		cellBits = int(unsafe.Sizeof(Cell(0))) * 8
+		cellBits = CellBits
 	case 32, 64:
 	default:
 		return nil, 0, errors.Errorf("loading of %d bits images is not supported", cellBits)
@@ -132,7 +131,7 @@ func Save(fileName string, mem []Cell, cellBits int) error {
 		}
 	}()
 	if cellBits == 0 {
-		cellBits = int(unsafe.Sizeof(Cell(0))) * 8
+		cellBits = CellBits
 	}
 	switch cellBits {
 	case 32:

vm/vm.go

@@ -29,6 +29,14 @@ const (
 	addressSize = 1024
 )
 
+// Bits per Cell
+const (
+	// Compute the size of a Cell
+	_m       = ^uCell(0)
+	_log     = _m>>8&1 + _m>>16&1 + (_m>>31)>>1&1 // >>31>>1 is to trick go vet
+	CellBits = (1 << _log) << 3
+)
+
 // Instance represents an Ngaro VM instance.
 type Instance struct {
 	PC        int    // Program Counter (aka. Instruction Pointer)

vm/vm_int.go

@@ -20,3 +20,4 @@ package vm
 
 // Cell is the basic type stored in a VM memory location.
 type Cell int
+type uCell uint

vm/vm_int32.go

@@ -20,3 +20,4 @@ package vm
 
 // Cell is the basic type stored in a VM memory location.
 type Cell int32
+type uCell uint32

vm/vm_int64.go

@@ -20,3 +20,4 @@ package vm
 
 // Cell is the basic type stored in a VM memory location.
 type Cell int64
+type uCell uint64