Add some BIOS bindings, and a zero-terminated print string routine.

plat/cpm/descr

@@ -77,8 +77,8 @@ name led
 		(.e:{TAIL}={PLATFORMDIR}/libem.a \
 		           {PLATFORMDIR}/libsys.a \
 				   {PLATFORMDIR}/libc.a \
-		           {PLATFORMDIR}/libsys.a \
 				   {PLATFORMDIR}/libem.a \
+		           {PLATFORMDIR}/libsys.a \
 		           {PLATFORMDIR}/libend.a)
 	linker
 end

plat/cpm/include/cpm.h

@@ -83,6 +83,9 @@ extern uint8_t cpm_read_random_safe(FCB* fcb);
 /* Extends cpm_ramtop over the CCP, for a little extra space. */
 extern void cpm_overwrite_ccp(void);
 
+/* Like cpm_printstring, but uses C-style strings terminated with a \0. */
+extern void cpm_printstring0(const char* s);
+
 /*  0 */ extern void cpm_warmboot(void);
 /*  1 */ extern uint8_t cpm_conin(void);
 /*  2 */ extern void cpm_conout(uint8_t b);
@@ -126,4 +129,8 @@ extern void cpm_overwrite_ccp(void);
 #define cpm_get_user() cpm_get_set_user(0xff)
 #define cpm_set_user(u) cpm_get_set_user(u)
 
+extern uint8_t bios_conin(void);
+extern uint8_t bios_const(void);
+extern void bios_conout(uint8_t c);
+
 #endif

plat/cpm/libsys/bios_conin.s

@@ -0,0 +1,15 @@
+#
+#include "asm.h"
+
+.define _bios_conin
+_bios_conin:
+	lhld 1
+	lxi d, 6
+	dad d
+	push b
+	call .pchl
+	pop b
+	mov e, a
+	mvi d, 0
+	ret
+

plat/cpm/libsys/bios_conout.s

@@ -0,0 +1,21 @@
+#
+#include "asm.h"
+
+.define _bios_conout
+_bios_conout:
+	pop h			! pop return address
+	pop d           ! pop parameter into DE
+	push d
+	push h
+	
+	push b
+	mov c, e
+
+	lhld 1
+	lxi d, 9
+	dad d
+	call .pchl
+
+	pop b
+	ret
+

plat/cpm/libsys/bios_const.s

@@ -0,0 +1,16 @@
+#
+#include "asm.h"
+
+.define _bios_const
+_bios_const:
+	lhld 1
+	lxi d, 3
+	dad d
+	push b
+	call .pchl
+	pop b
+	mov e, a
+	mvi d, 0
+	ret
+
+

plat/cpm/libsys/close.c

@@ -1,6 +1,7 @@
 #include <stdlib.h>
 #include <errno.h>
 #include <unistd.h>
+#include <string.h>
 #include <cpm.h>
 #include "cpmsys.h"
 

plat/cpm/libsys/cpm_printstring0.s

@@ -0,0 +1,27 @@
+#
+#include "asm.h"
+
+! Prints a \0-terminated string.
+
+.define _cpm_printstring0
+_cpm_printstring0:
+	pop h		   ! pop return address
+	pop d          ! pop parameter (possibly junk)
+	push d
+	push h
+    
+.1:
+    ldax d         ! fetch byte
+    ora a
+    rz             ! exit if zero
+    inx d
+
+    push b         ! save FP as the BDOS will corrupt it
+    push d
+    mov e, a
+    mvi c, 2       ! conout
+    call 0x0005
+    pop d
+    pop b
+
+    jmp .1