sam: fix keyboard scan logic

With this fixed we now get key events. We don't get the right keys because the
keyboard map isn't yet correct.

diff --git a/Kernel/platform-sam/sam.s b/Kernel/platform-sam/sam.s
index 489968d..dcc538c 100644 (file)
--- a/Kernel/platform-sam/sam.s
+++ b/Kernel/platform-sam/sam.s
@@ -21,6 +21,7 @@
            .globl _platform_reboot
            .globl _platform_copier_l
            .globl _platform_copier_h
+           .globl _keyscan
 
             ; exported debugging tools
             .globl _platform_monitor
@@ -196,21 +197,30 @@ outcw:        in a,(248)
 ;
 _keyscan:
            ld hl, #_keyin
-           ld b, #0xFE
-keyscl:            ld c, #249                  ; need BC out to get address lines
-           in a, (c)
-           and #0xE0                   ; top 3 bits valid
-           ld d, a
-           ld c, #254
-           in a, (c)
-           and #0x1F                   ; low 5 bits
-           or d
+           ld bc, #0xFEFE              ; F9 is keyboard port (254)
+keyscl:
+           ; Read low 5 bits from port F9, with the mask in the top address
+           ; lines (contents of B)
+           in e, (c)
+           ; Do the same for port FE for the upper lines, load A before
+           ; so we keep the mask right
+           ld a,b
+           in a, (0xF9)
+           xor e
+           and #0xE0                   ; keep top 3 bits
+           xor e
+           ; Save our decode
+           cpl
            ld (hl), a
            inc hl
-           scf
            rlc b
            jr c, keyscl
+           ; Have we done all the lines (FE FD FB F7 EF DF BF 7F)
+           ; Now do FF which is the special case as we have no high bits
+           ; attached to it.
+           ld b,#0xFF
            in a, (c)
+           cpl
            and #0x1F
            ld (hl), a
            ret