Merge pull request #17 from skx/10-delete

Allow deleting files

cpm/cpm.go

@@ -123,6 +123,10 @@ func New(filename string, logger *slog.Logger) *CPM {
 		Desc:    "F_SNEXT",
 		Handler: SysCallFindNext,
 	}
+	sys[19] = CPMHandler{
+		Desc:    "F_DELETE",
+		Handler: SysCallDeleteFile,
+	}
 	sys[22] = CPMHandler{
 		Desc:    "F_MAKE",
 		Handler: SysCallMakeFile,

cpm/cpm_syscalls.go

@@ -199,6 +199,35 @@ func SysCallFindNext(cpm *CPM) error {
 	return nil
 }
 
+// SyscallDeleteFile deletes the filename specified by the FCB in DE.
+func SysCallDeleteFile(cpm *CPM) error {
+
+	// The pointer to the FCB
+	ptr := cpm.CPU.States.DE.U16()
+	// Get the bytes which make up the FCB entry.
+	xxx := cpm.Memory.GetRange(ptr, 36)
+
+	// Create a structure with the contents
+	fcbPtr := fcb.FromBytes(xxx)
+
+	// Get the name
+	name := fcbPtr.GetName()
+	ext := fcbPtr.GetType()
+
+	fileName := name
+	if ext != "" && ext != "   " {
+		fileName += "."
+		fileName += ext
+	}
+
+	// Delete the named file
+	err := os.Remove(fileName)
+	if os.IsNotExist(err) {
+		return nil
+	}
+	return err
+}
+
 // SysCallMakeFile creates the file named in the FCB given in DE
 func SysCallMakeFile(cpm *CPM) error {
 	// The pointer to the FCB

fcb/fcb.go

@@ -31,7 +31,7 @@ func (f *FCB) GetName() string {
 			t += string(c)
 		}
 	}
-	return t
+	return strings.TrimSpace(t)
 }
 
 // GetType returns the type/extension component of an FCB entry.
@@ -43,7 +43,7 @@ func (f *FCB) GetType() string {
 			t += string(c)
 		}
 	}
-	return t
+	return strings.TrimSpace(t)
 }
 
 // AsBytes returns the entry of the FCB in a format suitable

fcb/fcb_test.go

@@ -10,10 +10,10 @@ func TestFCBFromString(t *testing.T) {
 	if f.Drive != 1 {
 		t.Fatalf("drive wrong")
 	}
-	if f.GetName() != "FOO     " {
+	if f.GetName() != "FOO" {
 		t.Fatalf("name wrong, got '%v'", f.GetName())
 	}
-	if f.GetType() != "   " {
+	if f.GetType() != "" {
 		t.Fatalf("unexpected suffix '%v'", f.GetType())
 	}
 
@@ -25,7 +25,7 @@ func TestFCBFromString(t *testing.T) {
 	if f.GetName() != "THIS-IS-" {
 		t.Fatalf("name wrong, got '%v'", f.GetName())
 	}
-	if f.GetType() != "   " {
+	if f.GetType() != "" {
 		t.Fatalf("unexpected suffix '%v'", f.GetType())
 	}
 
@@ -54,7 +54,7 @@ func TestFCBFromString(t *testing.T) {
 	if f.Drive != 2 {
 		t.Fatalf("drive wrong")
 	}
-	if f.GetName() != "TEST    " {
+	if f.GetName() != "TEST" {
 		t.Fatalf("name wrong, got '%v'", f.GetName())
 	}
 	if f.GetType() != "C??" {

samples/Makefile

@@ -2,7 +2,7 @@
 #
 # The files we wish to generate.
 #
-all: cli-args.com create.com drive.com find.com ret.com user-num.com
+all: cli-args.com create.com delete.com drive.com find.com ret.com user-num.com
 
 
 #

samples/delete.z80

@@ -0,0 +1,52 @@
+;; delete.asm - Delete the named file
+;;
+
+FCB1:    EQU 0x5C
+
+BDOS_ENTRY_POINT:    EQU 5
+
+BDOS_OUTPUT_STRING:            EQU 9
+BDOS_DELETE_FILE:              EQU 19
+
+        ;;
+        ;; CP/M programs start at 0x100.
+        ;;
+        ORG 100H
+
+        ;; The FCB will be populated with the pattern/first argument,
+        ;; if the first character of that region is a space-character
+        ;; then we've got nothing to search for.
+        ld a, (FCB1 + 1)
+        cp 0x20             ; 0x20 = 32 == SPACE
+        jp nz, got_argument ; Not a space, so we can proceed
+
+        ;;
+        ;; No argument, so show the error and exit
+        ;;
+        ld de, usage_message
+        ld c,  BDOS_OUTPUT_STRING
+        call   BDOS_ENTRY_POINT
+        jr     exit_fn
+
+got_argument:
+        LD DE, FCB1
+        LD C, BDOS_DELETE_FILE
+        CALL BDOS_ENTRY_POINT
+
+exit_fn:
+        ;; exit
+        LD      C,0x00
+        CALL    BDOS_ENTRY_POINT
+
+
+;;;
+;;; The message displayed if no command-line argument was present.
+;;;
+usage_message:
+        db "Usage: DELETE FILENAME.EXT"
+
+        ;; note fall-through here :)
+newline:
+        db 0xa, 0xd, "$"
+
+END