From: Alan Cox <alan@etchedpixels.co.uk>
Date: Wed, 5 Nov 2014 00:08:32 +0000 (+0000)
Subject: msx2: initial bootstrap debugging
X-Git-Url: https://git.ndcode.org/public/gitweb.cgi?a=commitdiff_plain;h=fc696b9c8669713683243200b3c41e9f96a4aea2;p=FUZIX.git

msx2: initial bootstrap debugging

We get as far as enabling interrupts then curl up and die. The VDP
programming also doesn't set text80 but does produce some interesting
flashing blobs
---

diff --git a/Kernel/platform-msx2/crt0.s b/Kernel/platform-msx2/crt0.s
index dbab60fc..14bd2a2b 100644
--- a/Kernel/platform-msx2/crt0.s
+++ b/Kernel/platform-msx2/crt0.s
@@ -30,13 +30,21 @@
 		.globl s__INITIALIZER
 	        .globl kstack_top
 
-	        ; startup code @0
+		; Just for the benefit of the map file
+		.globl start
+
+	        ; startup code @0x100
 	        .area _CODE
 
 ;
 ; Execution begins with us correctly mapped and at 0x0x100
 ;
 start:		di
+		; Debug port
+		ld a, #0x23
+	        out (0x2e), a
+		ld a, #'@'
+		out (0x2f), a
 		ld sp, #kstack_top
 		; move the common memory where it belongs    
 		ld hl, #s__INITIALIZER
diff --git a/Kernel/platform-msx2/msx2.s b/Kernel/platform-msx2/msx2.s
index 6a94bdcb..608e8562 100644
--- a/Kernel/platform-msx2/msx2.s
+++ b/Kernel/platform-msx2/msx2.s
@@ -44,6 +44,11 @@
 	    .globl _vdpport
 	    .globl _infobits
 
+	    ;
+	    ; vdp - we must initialize this bit early for the vt
+	    ;
+	    .globl vdpinit
+
             .include "kernel.def"
             .include "../kernel.def"
 
@@ -79,15 +84,17 @@ _trap_reboot:
             .area _CODE
 
 init_early:
-	    ld a, #0x33			; multibyte/ascii
-	    out (0x2E), a
+	    ld a, #'F'
+	    out (0x2F), a
             ret
 
 init_hardware:
+	    ld a, #'U'
+	    out (0x2F), a
 	    ; save the useful bits of low memory first
 	    ld hl, (0x2B)
 	    ld (_infobits), a
-	    ld a, (0x06)
+	    ld a, (0x07)
 	    ld (_vdpport), a
 
 	    ; Size RAM
@@ -100,8 +107,17 @@ init_hardware:
             call _program_vectors
             pop hl
 
+	    ld a, #'Z'
+	    out (0x2F), a
+
             im 1 			; set CPU interrupt mode
 	    call _vtinit		; init the console video
+
+	    ld a, #'I'
+	    out (0x2F), a
+	    call  vdpinit
+	    ld a, #'X'
+	    out (0x2F), a
             ret
 
 
@@ -133,7 +149,6 @@ ramscan:
 ramwrapped:
 	    ld a, #3
 	    out (c), a
-	    ld a, (hl)
 	    ld (hl), #0x55
 	    out (c), b
 	    ld a, (hl)
@@ -169,7 +184,7 @@ pageslt256:
 
 	    ; set system RAM size in KB
 	    ld (_ramsize), hl
-	    ld de, #0xFFC0
+	    ld de, #0xFFD0
 	    add hl, de		; subtract 48K for the kernel
 	    ld (_procmem), hl
 	    ret
diff --git a/Kernel/platform-msx2/vdp.s b/Kernel/platform-msx2/vdp.s
index 77bac44c..d6aad926 100644
--- a/Kernel/platform-msx2/vdp.s
+++ b/Kernel/platform-msx2/vdp.s
@@ -15,17 +15,21 @@
 
 	    .globl _vdpport
 
+	    .globl vdpinit
+
 	    .area _CODE
 ;
 ;	Register write value E to register A
 ;
 vdpout:	    ld bc, (_vdpport)
-	    out (c), e
-	    out (c), d
+	    ld bc, #0x98 ; hardcode for the moment
+	    inc c			; Write port
+	    out (c), e			; Write the data
+	    out (c), d			; and then the register | 0x80
 	    ret
 
 ;
-;	FIXME: table.. and move into init ROM
+;	FIXME: table.. and move into init RAM
 ;
 vdpinit:    ld de, #0x8004		; M4 }
 	    call vdpout 		;    }	80x25 mode