Add experimental SUBR to call nanosleep() for experiments in reducing CPU load

This adds a SUBR, sb_YIELD, value (octal) 0322 which takes a single number
0..999999999 which is the number of nanoseconds to pass to nanosleep().

The return value is T if the call to nanosleep() was executed or NIL
if it was not (argument out-of-range, or other error in getting the
number from the argument).

To use this experimental SUBR in a sysout you should:

   (SETQ \INITSUBRS (CONS '(YIELD #o322) \INITSUBRS))

then you can define functions that use that SUBR:

   (DEFINEQ (BACKGROUND-YIELD (SUBRCALL YIELD 833333)))
   (COMPILE 'BACKGROUND-YIELD)
   (SETQ BACKGROUNDFNS (CONS 'BACKGROUND-YIELD BACKGROUNDFNS))

README.md

@@ -4,7 +4,7 @@ Maiko is the implementation of the Medley Interlisp virtual machine, for a
 byte-coded Lisp instruction set and some low-level functions for
 connecting with Lisp for access to display (via X11) and disk etc.
 
-For an overview, see [Medley Interlisp Introduction](https://github.com/Interlisp/medley/wiki/Medley-Interlisp-Introduction).
+Newcomers should check out the [Medley Interlisp Introduction](https://github.com/Interlisp/medley/wiki/Medley-Interlisp-Introduction).
 
 See [the Medley repository](https://github.org/Interlisp/medley) for
 * [Issues](https://github.com/Interlisp/medley/issues) (note that maiko issues are there too)
@@ -33,17 +33,18 @@ $ cd maiko/bin
 $ ./makeright x
 ```
 
-* The build will (attempt to) detect the OS-type and cpu-type. It will build binaries `lde` and `ldex` in `../ostype.cputype` (with .o files in `..ostype.cputype-x`. For example, Linux on a 64-bit x86 will use `linux.x86_64`, while MacOS 11 on a (new M1) Mac will use `darwin.aarch64`.
-* If you prefer using `gcc` over `clang`, you will need to edit the makefile fragment for your configuration (`makefile-ostype.cputype-x`) and comment out the line (with a #) that defines `CC` for `clang` and uncomment the line (delete the #) for the line that defines `CC` for `gcc`.
-* There is a cmake configuration (TBD To Be Described here).
+* The build will (attempt to) detect the OS-type and cpu-type. It will build binaries `lde` and `ldex` in `../ostype.cputype` (with .o files in `..ostype.cputype-x`. For example, Linux on a 64-bit x86 will use `linux.x86_64`, while MacOS 11 on (new) Mac will use `darwin.arm64`.
+* If you prefer using `gcc` over `clang`, you will need to edit the makefile fragment for your configuration (`makefile-ostype.cputype-x1) and comment out the line (with a #) that defines `CC` for `clang` and uncomment the line (delete the #) for the line that defines `CC` for `gcc`.
+* There is a cmake configuration (TBD)
 
 ### Building For MacOS
 
 * Running on MacOS requires an X server, and building on a Mac requires X client libraries.
-An X-server for MacOS (and X11 client libraries) can be freely obtained at https://www.xquartz.org/releases
+An X-server for x86 MacOS (and X11 client libraries) can be freely obtained at https://www.xquartz.org/
+For the new arm64 MacOS 11, you'll need https://x.org which you can get via MacPorts or Brew.
 
 ### Building for Windows 10
 
-Windows 10 currently requires "Docker for Desktop" or WSL2 and a (Windows X-server).
+Windows 10 currently requires "Docker for Desktop" or WSL2 -- basically a Linux virtual machine -- and a (Windows X-server).
 See [Medley's README](https://github.com/Interlisp/medley/blob/master/README.md) for more.
 

bin/makefile-init-linux.armv7l

@@ -1,27 +0,0 @@
-# Options for Linux, ARMv7 and X-Window INIT
-
-CC = gcc $(GCC_CFLAGS)
-#CC = clang $(CLANG_CFLAGS)
-
-XFILES = $(OBJECTDIR)xmkicon.o \
-	$(OBJECTDIR)xbbt.o \
-	$(OBJECTDIR)dspif.o \
-	$(OBJECTDIR)xinit.o \
-	$(OBJECTDIR)xscroll.o \
-	$(OBJECTDIR)xcursor.o \
-	$(OBJECTDIR)xlspwin.o \
-	$(OBJECTDIR)xrdopt.o \
-	$(OBJECTDIR)xwinman.o
-
-XFLAGS = -DXWINDOW
-
-# OPTFLAGS is normally -O2.
-OPTFLAGS =  -O0 -g3
-DFLAGS = $(XFLAGS) -DRELEASE=351 -DINIT
-
-LDFLAGS = -L/usr/X11/lib -lX11 -lc -lm
-LDELDFLAGS =  -L/usr/X11/lib -lX11 -lc -lm
-
-OBJECTDIR = ../$(RELEASENAME)/
-
-default	: ../$(OSARCHNAME)/lde 

bin/makefile-linux.aarch64-x

@@ -1,27 +0,0 @@
-# Options for Linux, ARMv7 and X-Window
-
-CC = gcc $(GCC_CFLAGS)
-#CC = clang $(CLANG_CFLAGS)
-
-XFILES = $(OBJECTDIR)xmkicon.o \
-	$(OBJECTDIR)xbbt.o \
-	$(OBJECTDIR)dspif.o \
-	$(OBJECTDIR)xinit.o \
-	$(OBJECTDIR)xscroll.o \
-	$(OBJECTDIR)xcursor.o \
-	$(OBJECTDIR)xlspwin.o \
-	$(OBJECTDIR)xrdopt.o \
-	$(OBJECTDIR)xwinman.o
-
-XFLAGS = -DXWINDOW
-
-# OPTFLAGS is normally -O2.
-OPTFLAGS =  -O2 -g3
-DFLAGS = $(XFLAGS) -DRELEASE=351
-
-LDFLAGS = -L/usr/X11/lib -lX11 -lc -lm
-LDELDFLAGS =  -L/usr/X11/lib -lX11 -lc -lm
-
-OBJECTDIR = ../$(RELEASENAME)/
-
-default	: ../$(OSARCHNAME)/lde ../$(OSARCHNAME)/ldex

inc/subrs.h

@@ -191,4 +191,6 @@
 #define user_subr_DUMMY	012
 #define user_subr_SAMPLE_USER_SUBR	00
 
+/* Experimental yield */
+#define sb_YIELD                        0322
 #endif

src/subr.c

@@ -29,6 +29,7 @@
 /***********************************************************/
 
 #include <stdio.h>
+#include <time.h>
 #include "lispemul.h"
 #include "address.h"
 #include "adr68k.h"
@@ -779,6 +780,20 @@ void OP_subrcall(int subr_no, int argnum) {
       break;
     }
 #endif /* LPSOLVE */
+  case sb_YIELD: {
+      struct timespec rqts = {0, 833333};
+      unsigned sleepnanos;
+      POP_SUBR_ARGS;
+      N_GETNUMBER(args[0], sleepnanos, ret_nil);
+      if (sleepnanos > 999999999) {
+          TopOfStack = NIL;
+          break;
+      }
+      rqts.tv_nsec = sleepnanos;
+      nanosleep(&rqts, NULL);
+      TopOfStack = ATOM_T;
+      break;
+  }
     default: {
       char errtext[200];
       sprintf(errtext, "OP_subrcall: Invalid alpha byte 0%o", ((*(PC + 1)) & 0xff));