Allow creating (empty) files.

cpm/cpm.go

@@ -123,6 +123,10 @@ func New(filename string, logger *slog.Logger) *CPM {
 		Desc:    "F_SNEXT",
 		Handler: SysCallFindNext,
 	}
+	sys[22] = CPMHandler{
+		Desc:    "F_MAKE",
+		Handler: SysCallMakeFile,
+	}
 	sys[25] = CPMHandler{
 		Desc:    "DRV_GET",
 		Handler: SysCallDriveGet,

cpm/cpm_syscalls.go

@@ -36,7 +36,10 @@ func SysCallReadChar(cpm *CPM) error {
 	}
 
 	// restore the state of the terminal to avoid mixing RAW/Cooked
-	term.Restore(int(os.Stdin.Fd()), oldState)
+	err = term.Restore(int(os.Stdin.Fd()), oldState)
+	if err != nil {
+		return fmt.Errorf("error restoring terminal state %s", err)
+	}
 
 	// Return the character
 	cpm.CPU.States.AF.Hi = b[0]
@@ -196,6 +199,39 @@ func SysCallFindNext(cpm *CPM) error {
 	return nil
 }
 
+// SysCallMakeFile creates the file named in the FCB given in DE
+func SysCallMakeFile(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
+	}
+
+	// Create the file
+	file, err := os.OpenFile(fileName, os.O_RDONLY|os.O_CREATE, 0644)
+	if err != nil {
+		return err
+	}
+	err = file.Close()
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
 // SysCallDriveGet returns the number of the active drive.
 func SysCallDriveGet(cpm *CPM) error {
 	cpm.CPU.States.AF.Hi = cpm.currentDrive

samples/Makefile

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

samples/create.z80

@@ -0,0 +1,52 @@
+;; create.asm - Create the named file
+;;
+
+FCB1:    EQU 0x5C
+
+BDOS_ENTRY_POINT:    EQU 5
+
+BDOS_OUTPUT_STRING:            EQU 9
+BDOS_MAKE_FILE:                EQU 22
+
+        ;;
+        ;; 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, 22
+        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: CREATE FILENAME.EXT"
+
+        ;; note fall-through here :)
+newline:
+        db 0xa, 0xd, "$"
+
+END