New calling conventions for read

git-svn-id: svn://svn.cc65.org/cc65/trunk@1548 b7a2c559-68d2-44c3-8de9-860c34a00d81

include/modload.h

@@ -50,20 +50,24 @@
  * code of mod_load before accessing any of these additional struct members.
  */
 struct mod_ctrl {
-    /* Parameters passed into the loader routine. The second pointer
+    /* Parameters passed into the loader routine. The member callerdata
-     * (callerdata) is an opaque pointer that may be used by the caller to
+     * is an opaque 16 bit datatype that may be used by the caller to
      * pass data through to the read routine. The read routine is used by the
      * loader to load any required data. There are several calls where the
-     * read routine is called with a size of 1, so you may choose to make this
+     * read routine is passed a count of 1, so you may choose to make this
-     * a special case when implementing read().
+     * a special case when implementing read(). The read() should return the
+     * number of bytes actually read. If the return value differs from the
+     * passed count, this is considered an error.
+     * NOTE: read() is designed so that the POSIX read() routine can be used
+     * for this vector, if you're loading from disk.
      */
-    unsigned char   (*read) (struct mod_ctrl*, void* buffer, unsigned size);
+    int               (*read) (int callerdata, void* buffer, unsigned count);
-    void*           callerdata;
+    int               callerdata;
 
     /* Parameters set by the loader routine */
-    void*           module;             /* Pointer to module data */
+    void*             module;           /* Pointer to module data */
-    unsigned        module_size;        /* Total size of loaded module */
+    unsigned          module_size;      /* Total size of loaded module */
-    unsigned        module_id;          /* Module id */
+    unsigned          module_id;        /* Module id */
 };
 
 
@@ -77,7 +81,7 @@ unsigned char mod_load (struct mod_ctrl* ctrl);
 
 void mod_free (void* module);
 /* Free a loaded module. Note: The given pointer is the pointer to the
- * module memory, not a pointer to a control structure. 
+ * module memory, not a pointer to a control structure.
  */
 
 

libsrc/common/modload.s

@@ -85,12 +85,16 @@ ExpectedHdrSize = * - ExpectedHdr
 
 
 ;------------------------------------------------------------------------------
-; PushCtrl: Push the address of the control structure onto the C stack.
+; PushCallerData: Push the callerdata member from control structure onto the
+; C stack.
 
 .code
-PushCtrl:
+PushCallerData:
-        lda     Ctrl
+        ldy     #MODCTRL_CALLERDATA+1
-        ldx     Ctrl+1
+        lda     (Ctrl),y
+        tax
+        dey
+        lda     (Ctrl),y
         jmp     pushax
 
 ;------------------------------------------------------------------------------
@@ -130,6 +134,47 @@ GetReloc:
         ldx     #>__ZP_START__
         rts
 
+;------------------------------------------------------------------------------
+; ReadByte: Read one byte with error checking into InputByte and A.
+; ReadAndCheckError: Call read with the current C stack and check for errors.
+
+.bss
+ReadSize:       .res    2
+
+.code
+ReadByte:
+
+; C->read (C->callerdata, &B, 1)
+
+        jsr     PushCallerData
+        lda     #<InputByte
+        ldx     #>InputByte
+        jsr     pushax
+        ldx     #0
+        lda     #1
+
+; This is a second entry point used by the other calls to Read
+
+ReadAndCheckError:
+        sta     ReadSize
+        stx     ReadSize+1
+        jsr     pushax
+        jsr     Read
+
+; Check the return code and bail out in case of problems
+
+        cmp     ReadSize
+        bne     @L1
+        cpx     ReadSize+1
+        beq     @L2                     ; Jump if ok
+@L1:    lda     #MLOAD_ERR_READ
+        bne     CleanupAndExit
+
+; Done
+
+@L2:    lda     InputByte               ; If called ReadByte, load the byte read
+Done:   rts
+
 ;------------------------------------------------------------------------------
 ; FormatError: Bail out with an o65 format error
 
@@ -174,38 +219,6 @@ CleanupAndExit:
         pla
         rts
 
-;------------------------------------------------------------------------------
-; ReadByte: Read one byte with error checking into InputByte and A.
-; ReadAndCheckError: Call read with the current C stack and check for errors.
-
-.code
-ReadByte:
-
-; C->read (C, &B, 1)
-
-        jsr     PushCtrl
-        lda     #<InputByte
-        ldx     #>InputByte
-        jsr     pushax
-        jsr     push1
-
-; This is a second entry point used by the other calls to Read
-
-ReadAndCheckError:
-        jsr     Read
-
-; Check the return code and bail out in case of problems
-
-        tax
-        beq     @L1                     ; Jump if ok
-        lda     #MLOAD_ERR_READ
-        bne     CleanupAndExit
-
-; Done
-
-@L1:    lda     InputByte               ; If called ReadByte, load the byte read
-Done:   rts
-
 ;------------------------------------------------------------------------------
 ; RelocSeg: Relocate the segment pointed to by a/x
 
@@ -331,14 +344,14 @@ _mod_load:
         lda     (Ctrl),y
         sta     Read+2
 
-; Read the o65 header: C->read (C, &H, sizeof (H))
+; Read the o65 header: C->read (C->callerdata, &H, sizeof (H))
 
-        jsr     PushCtrl
+        jsr     PushCallerData
         lda     #<Header
         ldx     #>Header
         jsr     pushax
         lda     #O65_HDR_SIZE
-        jsr     pusha0                  ; Always less than 256
+        ldx     #0                      ; Always less than 256
         jsr     ReadAndCheckError       ; Bails out in case of errors
 
 ; We read the o65 header successfully. Validate it.
@@ -483,15 +496,14 @@ GotMem: lda     Module
 
 ; Load code and data segment into memory. The sum of the sizes of
 ; code+data segment is still in TPtr.
-; C->read (C, C->module, H.tlen + H.dlen)
+; C->read (C->callerdata, C->module, H.tlen + H.dlen)
 
-        jsr     PushCtrl
+        jsr     PushCallerData
         lda     Module
         ldx     Module+1
         jsr     pushax
         lda     TPtr
         ldx     TPtr+1
-        jsr     pushax
         jsr     ReadAndCheckError       ; Bails out in case of errors
 
 ; We've got the code and data segments in memory. Next section contains