From b8446c868707ac1b86b482aac03002a2b585dbb6 Mon Sep 17 00:00:00 2001
From: Clyne Sullivan <clyne@bitgloo.com>
Date: Fri, 24 Jan 2025 10:45:22 -0500
Subject: [PATCH] branching, if-else-then; test arm compile

---
 Makefile |  7 +++++--
 foci.c   |  8 +++++++-
 foci.h   | 21 +++++++++++++++------
 3 files changed, 27 insertions(+), 9 deletions(-)

diff --git a/Makefile b/Makefile
index e3ccc3d..3408355 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,9 @@
+#CC := arm-none-eabi-gcc -mcpu=cortex-m4 -mthumb
 CC := gcc
 CFLAGS := -O3 -ggdb -g3 -Wall -Wextra
 
-all:
-	$(CC) $(CFLAGS) -c foci.c
+all: foci
 	$(CC) $(CFLAGS) main.c foci.o -o main
+
+foci:
+	$(CC) $(CFLAGS) -c foci.c
diff --git a/foci.c b/foci.c
index 9c73a04..2ca054f 100644
--- a/foci.c
+++ b/foci.c
@@ -101,7 +101,13 @@ W(colon,  ":",      &w_align)   FTH(here), LIT(0), comma, FTH(latest), comma,
                                 poke, comp, END
 I(semic,  ";",      &w_colon)   LIT(fexit), comma, LIT(&latest), poke, intr, END
 I(literal, "literal", &w_semic) LIT(push), comma, comma, END
-#define LATEST      &w_literal
+N(b,      "_b",     &w_literal) { ++pp; pp = (intptr_t **)*pp; NEXT; }
+N(bz,     "_bz",    &w_literal) { ++pp; if (!*sp++) { pp = (intptr_t **)*pp; } NEXT; }
+I(fif,    "if",     &w_b)       LIT(bz), comma, FTH(here), LIT(0), comma, END
+I(then,   "then",   &w_fif)     FTH(here), LIT(sizeof(intptr_t)), sub, swap, poke, END
+I(felse,  "else",   &w_then)    LIT(b), comma, FTH(here), LIT(0), comma, swap,
+                                FTH(here), LIT(sizeof(intptr_t)), sub, swap, poke, END
+#define LATEST      &w_felse
 
 void call(void *ptr)
 {
diff --git a/foci.h b/foci.h
index 48c5871..6a96f32 100644
--- a/foci.h
+++ b/foci.h
@@ -49,8 +49,6 @@
 #define N(name, tname, prev) NATIVE(name, tname, prev, 0)
 #define C(name, tname, prev) NATIVE(name, tname, prev, ATTR_IMMEDIATE)
 
-#define STASH   asm("push %r12; push %r13; push %r14; push %r15")
-#define RESTORE asm("pop %r15; pop %r14; pop %r13; pop %r12")
 #define NEXT    { goto *(*++pp); }
 
 struct word_t
@@ -61,10 +59,21 @@ struct word_t
     char name[];
 } __attribute__ ((packed));
 
-register intptr_t     tmp asm("r12");
-register intptr_t *   sp  asm("r13"); // pointer to stack cells
-register intptr_t *** rp  asm("r14"); // stack of pp
-register intptr_t **  pp  asm("r15"); // pointer to ip
+// ARM Cortex-M:
+//register intptr_t *   sp  asm("r0"); // pointer to stack cells
+//register intptr_t *** rp  asm("r1"); // stack of pp
+//register intptr_t **  pp  asm("r2"); // pointer to ip
+//register intptr_t     tmp asm("r8");
+//#define STASH             asm("push {r0-r2,r8}")
+//#define RESTORE           asm("pop {r0-r2,r8}")
+
+// x86_64
+register intptr_t *   sp  asm("r12"); // pointer to stack cells
+register intptr_t *** rp  asm("r13"); // stack of pp
+register intptr_t **  pp  asm("r14"); // pointer to ip
+register intptr_t     tmp asm("r15");
+#define STASH             asm("push %r12; push %r13; push %r14")
+#define RESTORE           asm("pop %r14; pop %r13; pop %r12")
 
 void init(void);
 int depth(void);