Fix #143 (Frame Buffer: *HELP MOS loops forever)

Change-Id: If51b0a7f5a515e574f3f4e972652988c36a0d8ae
hoglet67 · Dec 7, 2021 · fe913a2 · fe913a2
1 parent fc1bfd0
commit fe913a2
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Showing 4 changed files with 71 additions and 36 deletions.
diff --git a/src/programs.c b/src/programs.c
@@ -2803,18 +2803,22 @@ static const unsigned char dormann_d65c02[] = {
 
 #endif
 
-// Careful, this is currently 252 bytes (4 spare!)
+// Careful, this now starts at &2C0
 
 static const unsigned char osword_driver[] = {
-  0xa9, 0x20, 0x20, 0xee, 0xff, 0xa9, 0x09, 0x85, 0x81, 0xa0, 0x0a, 0x84,
-  0x80, 0xb9, 0x5d, 0x03, 0x5a, 0x20, 0x4f, 0x03, 0x7a, 0x88, 0x10, 0xf3,
-  0xc8, 0xa9, 0x04, 0xa2, 0x01, 0x20, 0xf4, 0xff, 0xa9, 0x68, 0x8d, 0x0e,
-  0x02, 0xa9, 0x03, 0x8d, 0x0f, 0x02, 0xad, 0x0c, 0x02, 0x8d, 0x71, 0x03,
-  0xad, 0x0d, 0x02, 0x8d, 0x72, 0x03, 0xa9, 0x6c, 0x8d, 0x0c, 0x02, 0xa9,
-  0x03, 0x8d, 0x0d, 0x02, 0xa9, 0x02, 0x85, 0x81, 0xa9, 0x0e, 0x85, 0x80,
-  0xa9, 0x00, 0x20, 0x4f, 0x03, 0xa9, 0x09, 0x85, 0x84, 0xa9, 0x06, 0xa2,
-  0x80, 0xa0, 0x00, 0x20, 0xf1, 0xff, 0xe6, 0x80, 0x60, 0x48, 0xa9, 0x03,
-  0x8d, 0xe2, 0xfe, 0x68, 0x8d, 0xe4, 0xfe, 0x60, 0x8d, 0xf8, 0xfe, 0x60,
+  0x48, 0xc9, 0x0c, 0xf0, 0x1b, 0xc9, 0x0d, 0xf0, 0x17, 0xc9, 0x1e, 0xf0,
+  0x13, 0xc9, 0x20, 0x90, 0x14, 0xee, 0x18, 0x03, 0xad, 0x18, 0x03, 0x18,
+  0x6d, 0x08, 0x03, 0xcd, 0x0a, 0x03, 0x90, 0x05, 0xa9, 0x00, 0x8d, 0x18,
+  0x03, 0xa9, 0x03, 0x8d, 0xe2, 0xfe, 0x68, 0x8d, 0xe4, 0xfe, 0x60, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0xa9, 0x09, 0x85, 0x81, 0xa0, 0x2e, 0x84, 0x80,
+  0xb9, 0xc0, 0x02, 0x5a, 0x20, 0x4a, 0x03, 0x7a, 0x88, 0x10, 0xf3, 0xc8,
+  0xa9, 0x04, 0xa2, 0x01, 0x20, 0xf4, 0xff, 0xa9, 0x58, 0x8d, 0x0e, 0x02,
+  0xa9, 0x03, 0x8d, 0x0f, 0x02, 0xad, 0x0c, 0x02, 0x8d, 0x61, 0x03, 0xad,
+  0x0d, 0x02, 0x8d, 0x62, 0x03, 0xa9, 0x5c, 0x8d, 0x0c, 0x02, 0xa9, 0x03,
+  0x8d, 0x0d, 0x02, 0xa9, 0x02, 0x85, 0x81, 0xa9, 0x0e, 0x85, 0x80, 0xa9,
+  0x00, 0x20, 0x4a, 0x03, 0xa9, 0x09, 0x85, 0x84, 0xa9, 0x06, 0xa2, 0x80,
+  0xa0, 0x00, 0x20, 0xf1, 0xff, 0xe6, 0x80, 0x60, 0x8d, 0xf8, 0xfe, 0x60,
   0xc9, 0x00, 0xf0, 0x03, 0x4c, 0xea, 0xea, 0x86, 0xf0, 0x84, 0xf1, 0xa0,
   0x04, 0xb1, 0xf0, 0x99, 0xb1, 0x02, 0x88, 0xc0, 0x02, 0xb0, 0xf6, 0xb1,
   0xf0, 0x85, 0xe9, 0x88, 0xb1, 0xf0, 0x85, 0xe8, 0x90, 0x07, 0xa9, 0x07,
@@ -2829,8 +2833,10 @@ static const unsigned char osword_driver[] = {
   0xa0, 0xb0, 0x9d, 0x20, 0xe7, 0xff, 0xa5, 0xff, 0x2a, 0xa9, 0x00, 0x60
 };
 
+const unsigned char *host_oswrch_redirector = osword_driver;
+
 void copy_test_programs(uint8_t *memory) {
-   memcpy(memory + 0x300, osword_driver, sizeof(osword_driver));
+   memcpy(memory + 0x2C0, osword_driver, sizeof(osword_driver));
 
    memcpy(memory + 0x800, sphere, sizeof(sphere));
 

diff --git a/src/programs.h b/src/programs.h
@@ -3,7 +3,8 @@
 #ifndef PROGRAMS_H
 #define PROGRAMS_H
 
+extern const unsigned char *host_oswrch_redirector;
+
 extern void copy_test_programs(uint8_t *memory);
 
 #endif
-
diff --git a/src/tube-commands.c b/src/tube-commands.c
@@ -12,6 +12,7 @@
 #include "gitversion.h"
 #include "copro-defs.h"
 #include "utils.h"
+#include "programs.h"
 
 static int doCmdHelp(const char *params);
 static int doCmdTest(const char *params);
@@ -402,16 +403,9 @@ int doCmdPiVDU(const char *params) {
       beeb_vdu(13);
       beeb_vdu(32);
       if (device & VDU_PI) {
-         // Install a host oswrch redirector (for output of OSCLI commands)
-         // PHA        48
-         // LDA #&03   A9 03
-         // STA &FEE2  8D E2 FE
-         // PLA        68
-         // STA &FEE4  8D E4 FE
-         // RTS        60
-         uint8_t data[] = { 0x48, 0xa9, 0x03, 0x8d, 0xe2, 0xfe, 0x68, 0x8d, 0xe4, 0xfe, 0x60} ;
-         for (uint16_t i = 0; i < sizeof(data); i++) {
-            write_host_byte(WRCHANDLER + i, data[i]);
+         // Install the same host oswrch redirector used by the 6502
+         for (uint16_t i = 0; i < 0x40; i++) {
+            write_host_byte(WRCHANDLER + i, host_oswrch_redirector[i]);
          }
          write_host_word(WRCVEC, WRCHANDLER);
       }

diff --git a/tools/frame_buffer/osword.asm b/tools/frame_buffer/osword.asm
@@ -23,15 +23,58 @@ osword6_addr_lo = osword6_param + 0
 osword6_addr_hi = osword6_param + 1
 osword6_data    = osword6_param + 4
 
-org &0300
+org &02C0
+guard &300
 
 .start
 
-.init
+;; Host-side OSWRCH Redirector
+;;
+;; This redirects OSWRCH calls on the host back over to the Pi VDU driver
+;;
+;; It's used for the output of MOS command (like *CAT, *HELP, etc)
+
+.host_oswrch_start
+    ;; Stack the character to be printed
+    PHA
+    ;; Emulate the POS VDU variable at &0318
+    ;; This is used directly by *HELP MOS for padding and also by *CAT in ADFS
+    CMP #12         ; Clear screen returns cursor to POS=0
+    BEQ zero_pos
+    CMP #13         ; So does carriage return
+    BEQ zero_pos
+    CMP #30         ; So does home cursor
+    BEQ zero_pos
+    ;; There are other cases we ignore for now (VDU 8; VDU 9; VDU 31,x,y; VDU 127)
+    ;; as these are very unlikely to be emitted by the POS commands that read back POS
+    CMP #32         ; Set C=1 if printable char (i.e. space or greater)
+    BCC write_fifo
+    INC &0318       ; printable char, so increment POS by one
+    LDA &0318       ; compare POS to the window width
+    CLC
+    ADC &0308       ; plus Window Left
+    CMP &030A       ; compare to Window Right
+    BCC write_fifo  ; Still within window?
+.zero_pos
+    ;; Zero pos (cursor in left most columb)
+    LDA #&00
+    STA &0318
+.write_fifo
+    ;; Select the VDU FIFO at &FEE4
+    LDA #&03
+    STA &FEE2
+    ;; Restore the character to be printed
+    PLA
+    ;; Write character to the VDU FIFO
+    STA &FEE4
+    RTS
+.host_oswrch_end
+
+org &0300
+clear &300,&3ff
+guard &400
 
-;; Leave cursor in col 1
-    LDA #32
-    JSR oswrch
+.init
 
 ;; Copy minimal OSWRCH to host at 0900
     LDA #page
@@ -87,15 +130,6 @@ org &0300
     INC osword6_addr_lo
     RTS
 
-.host_oswrch_start
-    PHA
-    LDA #&03
-    STA &FEE2
-    PLA
-    STA &FEE4
-    RTS
-.host_oswrch_end
-
 .parasite_oswrch
     STA &FEF8
     RTS