Merge pull request #604 from blackystardust/master

Improved reu size detection.

doc/c128.sgml

@@ -221,10 +221,8 @@ missing on VDC, and are translated to the two colors missing from the VIC palett
   Will test the hardware for the available RAM.
 
   <tag><tt/c128-reu.emd (c128_reu_emd)/</tag>
-  A driver for the CBM REUs. The driver will determine from the connected REU
+  A driver for the CBM REUs. The driver will test the connected REU to find
-  if it supports 128KB of RAM or more. In the latter case, 256KB are assumed,
+  out how much RAM is present.
-  but since there are no range checks, the application can use more memory if
-  it has better knowledge about the hardware than the driver.
 
   <tag><tt/c128-vdc.emd (c128_vdc_emd)/</tag>
   A driver for the VDC memory of the C128, written and contributed by Maciej

doc/c64.sgml

@@ -300,10 +300,8 @@ Note that the graphics drivers are incompatible with the
   Will test the hardware for the available RAM.
 
   <tag><tt/c64-reu.emd (c64_reu_emd)/</tag>
-  A driver for the CBM REUs. The driver will determine from the connected REU
+  A driver for the CBM REUs. The driver will test the connected REU to find
-  if it supports 128KB of RAM or more. In the latter case, 256KB are assumed,
+  out how much RAM is present.
-  but since there are no range checks, the application can use more memory if
-  it has better knowledge about the hardware than the driver.
 
   <tag><tt/c64-vdc.emd (c64_vdc_emd)/</tag>
   A driver for the VDC memory of the C128. Written and contributed by Maciej

libsrc/c128/emd/c128-reu.s

@@ -55,6 +55,8 @@ REU_TRIGGER     = $FF00                 ; REU command trigger
 OP_COPYFROM     = $ED
 OP_COPYTO       = $EC
 
+OP_COPYFROM_ALOAD = $B1
+OP_COPYTO_ALOAD   = $B0
 
 ; ------------------------------------------------------------------------
 ; Data.
@@ -92,17 +94,56 @@ INSTALL:
         cmp     REU_REUADDR             ; Check for presence of REU
         bne     nodevice
 
-        ldy     #>(128*4)               ; Assume 128KB
+; determine the size
-        lda     REU_STATUS
+        php
-        and     #$10                    ; Check size bit
+        sei
-        beq     @L1
-        ldy     #>(256*4)               ; 256KB when size bit is set
-@L1:    sty     pagecount+1
-
         ldy     #$FF
-        sty     curpage
+loop:
-        sty     curpage+1               ; Invalidate the current page
+        sty     window
-        txa                             ; X = A = EM_ERR_OK
+        jsr     reu_size_check_common
+        ldx     #OP_COPYTO_ALOAD
+        stx     REU_COMMAND
+        dey
+        cpy     #$FF
+        bne     loop
+        iny
+size_loop:
+        jsr     reu_size_check_common
+        ldx     #OP_COPYFROM_ALOAD
+        stx     REU_COMMAND
+        cpy     window
+        bne     size_found
+        iny
+        bne     size_loop
+size_found:
+        plp
+        ldx     #$00
+        cpy     #$00                    ; too many pages, shave off 2
+        bne     pagecount_ok
+        dex
+        dex
+        dey
+pagecount_ok:
+        stx     pagecount
+        sty     pagecount+1
+        lda     #<EM_ERR_OK
+        ldx     #>EM_ERR_OK
+        rts
+
+; common REU setup for size check
+reu_size_check_common:
+        sty     REU_REUADDR+2
+        ldx     #<window
+        stx     REU_C64ADDR
+        ldx     #>window
+        stx     REU_C64ADDR+1
+        ldx     #$00
+        stx     REU_REUADDR
+        stx     REU_REUADDR+1
+        stx     REU_COUNT+1
+        stx     REU_CONTROL
+        inx
+        stx     REU_COUNT
         rts
 
 ; No REU found

libsrc/c64/emd/c64-reu.s

@@ -55,6 +55,9 @@ REU_TRIGGER     = $FF00                 ; REU command trigger
 OP_COPYFROM     = $ED
 OP_COPYTO       = $EC
 
+OP_COPYFROM_ALOAD = $B1
+OP_COPYTO_ALOAD   = $B0
+
 
 ; ------------------------------------------------------------------------
 ; Data.
@@ -92,19 +95,59 @@ INSTALL:
         cmp     REU_REUADDR             ; Check for presence of REU
         bne     nodevice
 
-        ldy     #>(128*4)               ; Assume 128KB
+; determine the size
-        lda     REU_STATUS
+        php
-        and     #$10                    ; Check size bit
+        sei
-        beq     @L1
-        ldy     #>(256*4)               ; 256KB when size bit is set
-@L1:    sty     pagecount+1
-
         ldy     #$FF
-        sty     curpage
+loop:
-        sty     curpage+1               ; Invalidate the current page
+        sty     window
-        txa                             ; X = A = EM_ERR_OK
+        jsr     reu_size_check_common
+        ldx     #OP_COPYTO_ALOAD
+        stx     REU_COMMAND
+        dey
+        cpy     #$FF
+        bne     loop
+        iny
+size_loop:
+        jsr     reu_size_check_common
+        ldx     #OP_COPYFROM_ALOAD
+        stx     REU_COMMAND
+        cpy     window
+        bne     size_found
+        iny
+        bne     size_loop
+size_found:
+        plp
+        ldx     #$00
+        cpy     #$00                    ; too many pages, shave off 2
+        bne     pagecount_ok
+        dex
+        dex
+        dey
+pagecount_ok:
+        stx     pagecount
+        sty     pagecount+1
+        lda     #<EM_ERR_OK
+        ldx     #>EM_ERR_OK
         rts
 
+; common REU setup for size check
+reu_size_check_common:
+        sty     REU_REUADDR+2
+        ldx     #<window
+        stx     REU_C64ADDR
+        ldx     #>window
+        stx     REU_C64ADDR+1
+        ldx     #$00
+        stx     REU_REUADDR
+        stx     REU_REUADDR+1
+        stx     REU_COUNT+1
+        stx     REU_CONTROL
+        inx
+        stx     REU_COUNT
+        rts
+
+
 ; No REU found
 
 nodevice: