Merge pull request #81 from kernigh/kernigh-libfp

software floats, line editor for CP/M

build.lua

@@ -4,6 +4,7 @@ vars.cflags = {
 vars.ackcflags = {
 	"-O6"
 }
+vars.ackldflags = {}
 vars.plats = {
 	"cpm",
 	"linux386",

examples/build.lua

@@ -4,6 +4,10 @@ local conly = {
 	rpi = true
 }
 
+local softfp = {
+	cpm = true,
+}
+
 local sourcefiles = filenamesof(
 	"./hilo.b",
 	"./hilo.bas",
@@ -15,6 +19,11 @@ local sourcefiles = filenamesof(
 	"./startrek.c"
 )
 
+local usesfp = {
+	["mandelbrot.c"] = true,
+	["startrek.c"] = true,
+}
+
 local installmap = {}
 for _, file in ipairs(sourcefiles) do
 	local b = basename(file)
@@ -22,6 +31,12 @@ for _, file in ipairs(sourcefiles) do
 	local _, _, e = b:find("%.(%w*)$")
 
 	for _, plat in ipairs(vars.plats) do
+		local flags = {}
+
+		if softfp[plat] and usesfp[b] then
+			flags[#flags+1] = "-fp"
+		end
+
 		if (e == "c") or not conly[plat] then
 			local exe = ackprogram {
 				name = be.."_"..plat,
@@ -29,6 +44,7 @@ for _, file in ipairs(sourcefiles) do
 				vars = {
 					plat = plat,
 					lang = e,
+					["+ackldflags"] = flags,
 				}
 			}
 

examples/hilo.p

@@ -9,7 +9,6 @@ program hilo(input, output);
 
 type
 	string = packed array [0..255] of char;
-	charstar = packed array [0..0] of char;
 	
 var
 	playing : Boolean;
@@ -30,47 +29,25 @@ function random(range : integer) : integer;
 		random := seed mod range;
 	end;
 
-{ Pascal doesn't provide string input, so we interface to the read() syscall
+{ Pascal doesn't provide string input, so we read characters until the
-  and do it manually. But... we can't interface to read() directly because
+  end of line and put them in a string. }
-  that conflicts with a Pascal keyword. Luckily there's a private function
-  uread() in the ACK Pascal library that we can use instead. }
-  
-function uread(fd : integer; var buffer : charstar; count : integer) : integer;
-	extern;
-
-function readchar : char;
-	var
-		c : charstar;
-		dummy : integer;
-		
-	begin
-		c[0] := chr(0);
-		dummy := uread(0, c, 1);
-		readchar := c[0];
-	end;
 
 procedure readstring(var buffer : string; var length : integer);
 	var
-		finished : Boolean;
 		c : char;
 		
 	begin
 		write('> ');
 		
 		length := 0;
-		finished := FALSE;
+		repeat
-		seed := 0;
-		while not finished do
 			begin
-				c := readchar;
+				read(c);
-				if (ord(c) = 10) then
+				buffer[length] := c;
-					finished := true
+				length := length + 1;
-				else
+			end
-					begin
+		until eoln;
-						buffer[length] := c;
+		readln; { discard end of line }
-						length := length + 1;
-					end
-			end;
 	end;
 
 procedure getname;

examples/startrek.c

@@ -58,7 +58,18 @@
  *
  */
 
+/* For `ack -mcpm -fp`, the i80 code was too big.  Make it smaller by
+ * removing the game's intro and replacing part of libc. */
+#ifdef __i80
+#define SMALL
+#endif
+
+#ifdef SMALL
+#include <stdarg.h>
+#include <unistd.h>
+#else
 #include <stdio.h>
+#endif
 #include <stdlib.h>
 #include <string.h>
 #include <math.h>
@@ -134,13 +145,26 @@ int cint(double d);
 void compute_vector(void);
 void sub1(void);
 void sub2(void);
+#ifndef SMALL
 void showfile(char *filename);
 int openfile(char * sFilename, char * sMode);
 void closefile(void);
 int get_line(char *s);
+#endif
 void randomize(void);
 int get_rand(int iSpread);
 double rnd(void);
+#ifdef SMALL
+#undef atof
+#define atof    trek_atof
+#define getchar trek_getchar
+#define putchar trek_putchar
+#define printf  trek_printf
+double atof(const char *);
+static int getchar(void);
+static void putchar(int c);
+void printf(const char *fmt, ...);
+#endif
 
 /* Global Variables */
 
@@ -196,14 +220,20 @@ char sQ[194];                /* Visual Display of Quadrant */
 
 string sG2;                 /* Used to pass string results */
 
+#ifndef SMALL
 FILE *stream;
 bool bFlag = FALSE;         /* Prevent multiple file opens */
+#endif
 
 void
 reads(char* buffer)
 {
+#ifdef SMALL
+  read(0, buffer, sizeof(string));
+#else
   fflush(stdout);
   fgets(buffer, sizeof(string), stdin);
+#endif
 }
 
 /* Main Program */
@@ -224,6 +254,7 @@ intro(void)
 {
   string sTemp;
 
+#ifndef SMALL
   printf ("\n\n");
   printf (" *************************************\n");
   printf (" *                                   *\n");
@@ -239,6 +270,7 @@ intro(void)
 
   if (sTemp[0] == 'y' || sTemp[0] == 'Y')
     showfile("startrek.doc");
+#endif /* !SMALL */
 
   printf ("\n\n\n\n\n\n\n");
   printf("                         ------*------\n");
@@ -1879,6 +1911,7 @@ cint (double d)
   return(i);
 }
 
+#ifndef SMALL
 void
 showfile(char *filename)
 {
@@ -1934,6 +1967,7 @@ get_line(char *s)
   else
     return(strlen(s));
 }
+#endif /* !SMALL */
 
 /* Seed the randomizer with the timer */
 void
@@ -1960,3 +1994,164 @@ rnd(void)
   
   return(d);
 }
+
+#ifdef SMALL
+/* These are small but incomplete replacements for functions in libc.
+ * Local variables are static for smaller i80 code. */
+
+double
+atof(const char *str)
+{
+  static double d;
+  static char n, prec;
+
+  d = 0.0;
+  n = prec = 0; /* Forget to skip whitespace before number */
+  if (*str == '-') { n = 1; str++; }
+  for (;;)
+    {
+      if (*str >= '0' && *str <= '9')
+        {
+          d = 10.0 * d + (double)(*str - '0');
+          if (prec != 0) prec++;
+        }
+      else if (*str == '.')
+        prec++;
+      else
+        break; /* Forget to parse exponent like "e10" */
+      str++;
+    }
+  while (prec > 1) { d /= 10.0; prec--; }
+  return n ? -d : d;
+}
+
+static int
+getchar(void)
+{
+  static unsigned char c[2]; /* CP/M read() needs 2 bytes */
+
+  if (read(0, c, 2) > 0)
+    return c[0];
+  else
+    return -1;
+}
+
+static void
+putchar(int c)
+{
+  write(1, &c, 1);
+}
+
+struct printf_buf {
+  char  p_buf[13];
+  char  p_len;
+  char *p_str;
+};
+
+static struct printf_buf pfb;
+
+static void
+pfb_put(int c)
+{
+  if (pfb.p_str != pfb.p_buf)
+    {
+      pfb.p_str--;
+      *pfb.p_str = c; /* Prepend character to buffer */
+      pfb.p_len++;
+    }
+  else
+    pfb.p_len = 0; /* No room in buffer; force empty string */
+}
+
+void
+printf(const char *fmt, ...)
+{
+  static va_list ap;
+  static const char *s;
+
+  va_start(ap, fmt);
+  while (*fmt != '\0')
+    {
+      if (*fmt != '%')
+        {
+          s = fmt;
+          do { s++; } while ( *s != '\0' && *s != '%');
+          write(1, fmt, s - fmt);
+          fmt = s;
+        }
+      if (*fmt == '%')
+        {
+          static char prec, width;
+
+          fmt++; /* Pass '%' */
+          /* Read optional width.prec, as 4.2 in "%4.2f" */
+          prec = width = 0;
+          if (*fmt >= '0' && *fmt <= '9')
+            {
+              width = *fmt - '0';
+              fmt++;
+            }
+          if (*fmt == '.')
+            {
+              fmt++;
+              if (*fmt >= '0' && *fmt <= '9')
+                {
+                  prec = *fmt - '0';
+                  fmt++;
+                }
+            }
+          if (*fmt == 's') /* Format "%s" */
+            {
+              static const char *s;
+
+              s = va_arg(ap, const char *);
+              write(1, s, strlen(s));
+            }
+          else /* Format "%d" or "%f" */
+            {
+              static double d;
+              static char n, pad;
+
+              if (*fmt == 'd')
+                {
+                  d = (double)va_arg(ap, int);
+                  prec = 0; /* No digits after point */
+                  pad = '0';
+                }
+              else
+                {
+                  d = va_arg(ap, double);
+                  /* Move digits before point */
+                  for (n = prec; n != 0; n--) d *= 10.0;
+                  pad = ' ';
+                }
+              /* Set up buffer */
+              pfb.p_len = 0;
+              pfb.p_str = pfb.p_buf + sizeof(pfb.p_buf);
+              /* Change negative number to positive */
+              n = 0;
+              if (d < 0) { n = 1; d = -d; }
+              modf(d + 0.5, &d); /* Round last digit */
+              for (;;)
+                {
+                  d /= 10.0;  /* Extract next digit */
+                  /* Use 10.5 instead of 10.0 to decrease error */
+                  pfb_put('0' + (int)(10.5 * modf(d, &d)));
+                  if (prec != 0)
+                    {
+                      prec--;
+                      if (prec == 0) pfb_put('.');
+                    }
+                  else if (d < 1.0)
+                    break; /* No more digits */
+                }
+              if (n) pfb_put('-');
+              while(pfb.p_len < width) pfb_put(pad);
+              write(1, pfb.p_str, pfb.p_len);
+            }
+          fmt++; /* Pass 's' in "%s" */
+        }
+    }
+  va_end(ap);
+}
+#endif /* SMALL */

first/build.lua

@@ -40,6 +40,7 @@ definerule("cfile",
 	{
 		srcs = { type="targets" },
 		deps = { type="targets", default={} },
+		suffix = { type="string", default=".o" },
 		commands = {
 			type="strings",
 			default={
@@ -56,7 +57,7 @@ definerule("cfile",
 		end
 		hdrpaths = uniquify(hdrpaths)
 
-		local outleaf = basename(e.name)..".o"
+		local outleaf = basename(e.name)..e.suffix
 
 		return normalrule {
 			name = e.name,

mach/i80/libem/flp.s

@@ -1,7 +1,6 @@
 .define .adf4,.adf8,.sbf4,.sbf8,.mlf4,.mlf8,.dvf4,.dvf8
 .define .ngf4,.ngf8,.fif4,.fif8,.fef4,.fef8
-.define .zrf4,.zrf8
+.define .cfi,.cif4,.cif8,.cuf4,.cuf8,.cff4,.cff8,.cfu
-.define .cfi,.cif,.cuf,.cff,.cfu
 .define .cmf4,.cmf8
 .sect .text
 .sect .rom
@@ -25,12 +24,13 @@
 .fif8:
 .fef4:
 .fef8:
-.zrf4:
-.zrf8:
 .cfi:
-.cif:
+.cif4:
-.cuf:
+.cif8:
-.cff:
+.cuf4:
+.cuf8:
+.cff4:
+.cff8:
 .cfu:
 .cmf4:
 .cmf8:

mach/i80/ncg/mach.c

@@ -41,21 +41,12 @@ con_mult(sz) word sz; {
 	fprintf(codefile,".data4\t%ld\n",atol(str));
 }
 
-void
+#define CODE_GENERATOR
-con_float() {
+#define IEEEFLOAT
-	static int warning_given;
+#define FL_MSL_AT_LOW_ADDRESS   0
-	int i = argval;
+#define FL_MSW_AT_LOW_ADDRESS   0
-
+#define FL_MSB_AT_LOW_ADDRESS   0
-	if (!warning_given) {
+#include <con_float>
-		fprintf(stderr, "warning: dummy floating point constant\n");
-		warning_given = 1;
-	}
-	while (i > 0) {
-		fputs(".data4 0	!dummy float\n", codefile);
-		i -= 4;
-	}
-}
-
 
 void
 prolog(nlocals) full nlocals; {

mach/i80/ncg/table

@@ -817,61 +817,28 @@ gen mvi a,{const1,0}
 /* Group 5: Floating point arithmetic	    */
 /********************************************/
 
-pat adf $1==4
+pat adf $1==4					leaving cal ".adf4" asp 4
-kills ALL
+pat adf $1==8					leaving cal ".adf8" asp 8
-gen Call {label,".adf4"}
+pat sbf $1==4					leaving cal ".sbf4" asp 4
-
+pat sbf $1==8					leaving cal ".sbf8" asp 8
-pat adf $1==8
+pat mlf $1==4					leaving cal ".mlf4" asp 4
-kills ALL
+pat mlf $1==8					leaving cal ".mlf8" asp 8
-gen Call {label,".adf8"}
+pat dvf $1==4					leaving cal ".dvf4" asp 4
-
+pat dvf $1==8					leaving cal ".dvf8" asp 8
-pat sbf $1==4
+pat ngf $1==4					leaving cal ".ngf4"
-kills ALL
+pat ngf $1==8					leaving cal ".ngf8"
-gen Call {label,".sbf4"}
-
-pat sbf $1==8
-kills ALL
-gen Call {label,".sbf8"}
-
-pat mlf $1==4
-kills ALL
-gen Call {label,".mlf4"}
-
-pat mlf $1==8
-kills ALL
-gen Call {label,".mlf8"}
-
-pat dvf $1==4
-kills ALL
-gen Call {label,".dvf4"}
-
-pat dvf $1==8
-kills ALL
-gen Call {label,".dvf8"}
-
-pat ngf $1==4
-kills ALL
-gen Call {label,".ngf4"}
-
-pat ngf $1==8
-kills ALL
-gen Call {label,".ngf8"}
 
 pat fif $1==4
-kills ALL
+leaving lor 1 cal ".fif4" asp 2
-gen Call {label,".fif4"}
 
 pat fif $1==8
-kills ALL
+leaving lor 1 cal ".fif8" asp 2
-gen Call {label,".fif8"}
 
 pat fef $1==4
-kills ALL
+leaving lor 1 adp 0-2 cal ".fef4"
-gen Call {label,".fef4"}
 
 pat fef $1==8
-kills ALL
+leaving lor 1 adp 0-2 cal ".fef8"
-gen Call {label,".fef8"}
 
 /********************************************/
 /* Group 6: Pointer arithmetic              */
@@ -964,13 +931,9 @@ pat zre
 uses hlreg={const2,0}
 gen shld {label,$1}
 
-pat zrf $1==4
+pat zrf $1==4					leaving zer 4
-kills ALL
-gen Call {label,".zrf4"}
 
-pat zrf $1==8
+pat zrf $1==8					leaving zer 8
-kills ALL
-gen Call {label,".zrf8"}
 
 pat zer $1==2				yields {const2,0}
 
@@ -1086,25 +1049,51 @@ kills ALL
 gen mvi a,{const1,0}
     Call {label,".cii"}
 
-pat cfi
+pat loc loc cfi $2==2
-kills ALL
+leaving loc $1 loc $2 cal ".cfi" asp 4+$1 loe ".fra"
-gen Call {label,".cfi"}
 
-pat cif
+pat loc loc cfi $2==4
-kills ALL
+leaving loc $1 loc $2 cal ".cfi" asp 4+$1 lfr 4
-gen Call {label,".cif"}
 
-pat cuf
+pat loc loc cif $2==4
-kills ALL
+leaving loc $1 cal ".cif4" asp $1-2
-gen Call {label,".cuf"}
 
-pat cff
+pat loc loc cif $1==2 && $2==8
-kills ALL
+with hl_or_de
-gen Call {label,".cff"}
+gen push %1
+    push %1
+    push %1					leaving loc $1 cal ".cif8"
 
-pat cfu
+pat loc loc cif $1==4 && $2==8
-kills ALL
+with hl_or_de hl_or_de
-gen Call {label,".cfu"}
+gen push %2
+    push %2
+    push %1					leaving loc $1 cal ".cif8"
+
+pat loc loc cuf $2==4
+leaving loc $1 cal ".cuf4" asp $1-2
+
+pat loc loc cuf $1==2 && $2==8
+with hl_or_de
+gen push %1
+    push %1
+    push %1					leaving loc $1 cal ".cuf8"
+
+pat loc loc cuf $1==4 && $2==8
+with hl_or_de hl_or_de
+gen push %1
+    push %2
+    push %1					leaving loc $1 cal ".cuf8"
+
+pat loc loc cff $1==8 && $2==4			leaving cal ".cff4" asp 4
+
+pat loc loc cff $1==4 && $2==8			leaving dup 4 cal ".cff8"
+
+pat loc loc cfu $2==2
+leaving loc $1 loc $2 cal ".cfu" asp 4+$1 loe ".fra"
+
+pat loc loc cfu $2==4
+leaving loc $1 loc $2 cal ".cfu" asp 4+$1 lfr 4
 
 /*****************************************/
 /* Group 9: Logical instructions         */
@@ -1408,12 +1397,10 @@ gen mvi a,{const1,1}
     Call {label,".cmi4"}		yields de
 
 pat cmf $1==4
-kills ALL
+leaving cal ".cmf4" asp 8 lfr 2
-gen Call {label,".cmf4"}
 
 pat cmf $1==8
-kills ALL
+leaving cal ".cmf8" asp 16 lfr 2
-gen Call {label,".cmf8"}
 
 pat cmu $1==2
 with hl_or_de hl_or_de

mach/proto/fp/FP.script

@@ -37,5 +37,5 @@ g/_b64_add/s//.b64_add/g
 g/_b64_sft/s//.b64_sft/g
 g/_b64_rsft/s//.b64_rsft/g
 g/_b64_lsft/s//.b64_lsft/g
-w
+1,$p
 q

mach/proto/fp/build.lua

@@ -0,0 +1,53 @@
+include("plat/build.lua")
+
+-- For now, all floats are little-endian.
+local byte_order = "mach/i86/libfp/byte_order.h"
+
+-- For now, only cpm uses software floating-point.
+for _, plat in ipairs({"cpm"}) do
+	local edits = {}
+	for _, src in fpairs("./*.c", "./*.e") do
+
+		-- Compile each src file into assembly code.
+		local n = basename(src):gsub("%.%w*$", "")
+		local assembly = ackfile {
+			name = "s_"..plat.."/"..n,
+			srcs = { src },
+			deps = {
+				"./*.h",
+				byte_order,
+			},
+			suffix = ".s",
+			vars = {
+				["+ackcflags"] = { "-I"..dirname(byte_order) },
+				plat = plat
+			}
+		}
+
+		-- Run FP.script to edit the assembly code.
+		edits[#edits+1] = normalrule {
+			name = "ed_"..plat.."/"..n,
+			ins = {
+				"./FP.script",
+				assembly,
+			},
+			outleaves = { n..".s" },
+			commands = {
+				"ed -s %{ins[2]} <%{ins[1]} >%{outs}"
+			}
+		}
+	end
+
+	acklibrary {
+		name = "lib_"..plat,
+		srcs = { edits },
+		vars = { plat = plat }
+	}
+
+	installable {
+		name = "pkg_"..plat,
+		map = {
+			["$(PLATIND)/"..plat.."/libfp.a"] = "+lib_"..plat,
+		}
+	}
+end

plat/build.lua

@@ -8,8 +8,10 @@ definerule("ackfile",
 	{
 		srcs = { type="targets" },
 		deps = { type="targets", default={} },
+		suffix = { type="string", default=".o" },
 	},
 	function (e)
+		local c = (e.suffix == ".o" and "-c" or "-c"..e.suffix)
 		local plat = e.vars.plat
 
 		return cfile {
@@ -28,8 +30,9 @@ definerule("ackfile",
 				"util/misc+pkg",
 				e.deps
 			},
+			suffix = e.suffix,
 			commands = {
-				"ACKDIR=$(INSDIR) $(INSDIR)/bin/ack -m%{plat} -c -o %{outs} %{ins} %{hdrpaths} %{ackcflags}"
+				"ACKDIR=$(INSDIR) $(INSDIR)/bin/ack -m%{plat} "..c.." -o %{outs} %{ins} %{hdrpaths} %{ackcflags}"
 			}
 		}
 	end
@@ -88,7 +91,7 @@ definerule("ackprogram",
 			},
 			_clibrary = acklibrary,
 			commands = {
-				"ACKDIR=$(INSDIR) $(INSDIR)/bin/ack -m%{plat} -.%{lang} -o %{outs} %{ins}"
+				"ACKDIR=$(INSDIR) $(INSDIR)/bin/ack -m%{plat} -.%{lang} -o %{outs} %{ins} %{ackldflags}"
 			}
 		}
 	end
@@ -100,18 +103,25 @@ definerule("build_plat_libs",
 		plat = { type="string" },
 	},
 	function(e)
+		local installmap = {
+			"lang/b/lib+pkg_"..e.plat,
+			"lang/basic/lib+pkg_"..e.plat,
+			"lang/cem/libcc.ansi+pkg_"..e.plat,
+			"lang/m2/libm2+pkg_"..e.plat,
+			"lang/pc/libpc+pkg_"..e.plat,
+			"lang/b/lib+pkg_"..e.plat,
+			["$(PLATIND)/"..e.plat.."/libem.a"] = "mach/"..e.arch.."/libem+lib_"..e.plat,
+			["$(PLATIND)/"..e.plat.."/libend.a"] = "mach/"..e.arch.."/libend+lib_"..e.plat,
+		}
+
+		-- For now, only cpm uses software floating-point.
+		if e.plat == "cpm" then
+			installmap[#installmap+1] = "mach/proto/fp+pkg_"..e.plat
+		end
+
 		return installable {
 			name = e.name,
-			map = {
+			map = installmap,
-				"lang/b/lib+pkg_"..e.plat,
-				"lang/basic/lib+pkg_"..e.plat,
-				"lang/cem/libcc.ansi+pkg_"..e.plat,
-				"lang/m2/libm2+pkg_"..e.plat,
-				"lang/pc/libpc+pkg_"..e.plat,
-				"lang/b/lib+pkg_"..e.plat,
-				["$(PLATIND)/"..e.plat.."/libem.a"] = "mach/"..e.arch.."/libem+lib_"..e.plat,
-				["$(PLATIND)/"..e.plat.."/libend.a"] = "mach/"..e.arch.."/libend+lib_"..e.plat,
-			}
 		}
 	end
 )

plat/cpm/README

@@ -11,14 +11,15 @@ CP/M-compliant machine.
 
 This port only implements a very limited set of syscalls --- and most of those
 are stubs required to make the demo apps link. File descriptors 0, 1 and 2
-represent the console. All reads block. There's enough TTY emulation to allow
+represent the console. Each read() blocks and reads an entire line (it can't
-\n conversion and local echo (but it can't be turned off).
+read part of a line) from the CP/M line editor, then appends \n. Each write()
+converts \n to \r\n. The line editor and \n conversion can't be turned off.
 
 There's a special, if rather minimilist, interface to give applications access
 to CP/M. See include/cpm.h for details.
 
-IEEE floating point is not available. Attempts to use floating-point numbers 
+Link with `ack -fp` to enable software floating point. Otherwise, attempts to
-will cause the program to terminate.
+use floating-point numbers will cause the program to terminate.
 
 
 Example command line

plat/cpm/descr

@@ -58,7 +58,7 @@ name led
 	program {EM}/lib/ack/em_led
 	mapflag -l* LNAME={PLATFORMDIR}/lib*
 	mapflag -i SEPID=-b1:0
-	mapflag -fp FLOATS={EM}/{ILIB}fp
+	mapflag -fp FLOATS={PLATFORMDIR}/libfp.a
 	args {ALIGN} {SEPID?} \
 		({RTS}:.b=-u _i_main) \
 	    (.e:{HEAD}={PLATFORMDIR}/boot.o) \

plat/cpm/libsys/read.c

@@ -10,29 +10,44 @@
 
 int read(int fd, void* buffer, size_t count)
 {
-	char i;
+	short save;
+	unsigned char before_n;
 
 	/* We're only allowed to read from fd 0, 1 or 2. */
-	
 	if ((fd < 0) || (fd > 2))
 	{
 		errno = EBADF;
 		return -1;
 	}
 
-	/* Empty buffer? */
+	/* We need room for at least 1 char plus '\n'. */
+	if (count < 2)
+	{
+		errno = EINVAL;
+		return -1;
+	}
 
-	if (count == 0)
+	/* Make room to append '\n' later. */
-		return 0;
+	before_n = count > 255 ? 255 : count - 1;
 
-	/* Read one byte. */
+	/* Borrow 2 bytes of RAM before the buffer. */
+	/* This might overwrite count!!! */
+	save = ((short*)buffer)[-1];
 
-	cpm_bc_register = CPM_BDOS_CONSOLE_INPUT;
+	/* Read one line from the console. */
+	((unsigned char*)buffer)[-2] = before_n;
+	cpm_bc_register = CPM_BDOS_READ_CONSOLE_BUFFER;
+	cpm_de_register = (char*)buffer - 2;
+	cpm_bdos();
+	before_n = ((unsigned char*)buffer)[-1];
+
+	((char*)buffer)[before_n] = '\n'; /* Append '\n'. */
+	((short*)buffer)[-1] = save; /* Give back borrowed bytes. */
+
+	/* Echo '\n' to console. */
+	cpm_bc_register = CPM_BDOS_PRINT_STRING;
+	cpm_de_register = "\r\n$";
 	cpm_bdos();
 
-	if (cpm_a_register == '\r') 
+	return (int)before_n + 1;
-		cpm_a_register = '\n';
-	*(char*)buffer = cpm_a_register;
-	
-	return 1;
 }