From f99b95fcd2f2f870da3411e4de8cdd043a92fd30 Mon Sep 17 00:00:00 2001
From: Luxferre <lux@ferre>
Date: Wed, 10 Aug 2022 16:49:46 +0300
Subject: [PATCH] Implemented variable-length literals and strings

---
 equi.c | 47 ++++++++++++++++++++---------------------------
 1 file changed, 20 insertions(+), 27 deletions(-)

diff --git a/equi.c b/equi.c
index 49f4dca..81c6101 100644
--- a/equi.c
+++ b/equi.c
@@ -40,8 +40,6 @@
 #define ushort unsigned short /* basic 16-bit integer */
 #define uchar unsigned char /* basic 8-bit integer */
 #define WS sizeof(ushort) /* Equi word size in bytes */
-#define CLT_ENTRY_LEN 6u /* Amount of significant compiled word characters */
-#define CLT_ENTRY_SIZE (CLT_ENTRY_LEN + WS) /* Full size in bytes taken by one CLT entry */
 #define BS 8u /* Backspace character code */
 #define CR 13u /* Character return code */
 #define LF 10u /* Line feed code */
@@ -263,24 +261,14 @@ uchar a2d(uchar a) {
   return (a < 0x3aU) ? (a - 0x30U) : (a - 55U);
 }
 
-/* shape 2-byte vlaue on the main stack from the 4 values of the literal stack */
-void pushLitVal(strict) {
-  uchar p1, p2, p3, p4;
-  if(ram.lsp < 4U) { /* if we don't strictly expect 4 bytes, do nothing */
-    if(strict) trapout(STACK_UNDERFLOW);
-    else {
-      ram.lsp = 0; /* clear the literal stack */
-      return;
-    }
-  }
-  else {
-    p4 = a2d(popLit());
-    p3 = a2d(popLit());
-    p2 = a2d(popLit());
-    p1 = a2d(popLit());
-    pushMain((p1<<12U) | (p2<<8U) | (p3<<4U) | p4);
-    ram.lsp = 0; /* clear the literal stack */
-  }
+/* shape 2-byte vlaue on the main stack from  up to 4 values of the literal stack */
+void pushLitVal() {
+  uchar p[4U] = {0,0,0,0}, i, thr = 4U;
+  if(ram.lsp < 4U) thr = ram.lsp;
+  for(i=0;i<thr;++i)
+    p[3-i] = a2d(popLit());
+  pushMain((p[0]<<12U) | (p[1]<<8U) | (p[2]<<4U) | p[3]);
+  ram.lsp = 0; /* clear the literal stack */
 }
 
 /* CCITT CRC16 helper */
@@ -324,11 +312,11 @@ void equi_main_loop() {
     /* then, check for compilation mode */
     if(ram.CM) {
       if(instr == INS_CMEND) { /* trigger word compilation logic as per the spec */
-        if(ram.lsp < CLT_ENTRY_LEN)
+        if(ram.lsp < 1)
           trapout(STACK_UNDERFLOW);
         ram.cmdbuf[ram.pc] = INS_RET; /* in-place patch this instruction to R */
         /* hash and save compiled word */
-        ram.clt[ram.cltp].nhash = crc16(&ram.literal_stack[ram.lsp-CLT_ENTRY_LEN], CLT_ENTRY_LEN);
+        ram.clt[ram.cltp].nhash = crc16(&ram.literal_stack[0], ram.lsp);
         ram.lsp = 0; /* clear the literal stack */
         ram.clt[ram.cltp].loc = ram.cbp; /* stored the compiled code location from the most recent CBP value */
         ++ram.cltp; /* increase the word */
@@ -346,7 +334,7 @@ void equi_main_loop() {
     }
     /* then trigger literal auto-push if applicable */
     if(ram.lsp > 0 && instr != INS_LITSTR && instr != INS_LITCALL && instr != INS_LITINT && instr != INS_CMSTART)
-      pushLitVal(0);
+      pushLitVal();
     switch(instr) { /* then perform all main interpretation logic */
       case INS_IISTART: /* instruction ignore start */
         ram.II = 1; /* raise II flag */
@@ -363,7 +351,7 @@ void equi_main_loop() {
       case INS_QUIT: /* gracefully quit the interpretation mode */
         goto brx;
       case INS_LITINT: /* literal stack -> main stack as short */
-        pushLitVal(1U);
+        pushLitVal();
         break;
       case INS_LITSTR: /* literal stack -> each char at main stack as short */
         while(ram.lsp)
@@ -371,9 +359,9 @@ void equi_main_loop() {
         ram.lsp = 0;
         break;
       case INS_LITCALL: /* call the saved word from the literal */
-        if(ram.lsp < CLT_ENTRY_LEN)
+        if(ram.lsp < 1)
           trapout(STACK_UNDERFLOW);
-        lhash = crc16(&ram.literal_stack[ram.lsp-CLT_ENTRY_LEN], CLT_ENTRY_LEN);
+        lhash = crc16(&ram.literal_stack[0], ram.lsp);
         for(pbuf=0;pbuf<CLT_ENTRIES_MAX;++pbuf)
           if(ram.clt[pbuf].nhash == lhash) {
             ram.pc = ram.clt[pbuf].loc;
@@ -526,6 +514,8 @@ void equi_main_loop() {
   /* unset interpretation mode flag and exit */
   ram.IM = 0;
   ram.pc = ram.ibp = 65535U;
+  /* clear all stacks and CLT */
+  ram.msp = ram.rsp = ram.lsp = ram.cltp = 0;
 }
 
 /* Equi VM entry point */
@@ -572,10 +562,13 @@ int main(int argc, char* argv[]) {
       cputc(instr); /* echo it */
 #endif
       ram.II = 0;
-    } else if(instr == LF) { /* process carriage return */
+    } else if(instr == CR || instr == LF) { /* process carriage return or linefeed */
+      cputc(CR); /* echo it */
       cputc(LF); /* echo it */
+      ram.cmdbuf[ram.ibp] = 0; /* replace itself with 0 */
       ram.IM = 1; /* set the mandatory interpretation mode flag */
       equi_main_loop(); /* and run the interpreter loop */
+      cputc(CR); /* echo it */
       cputc(LF); /* echo it */
       cputc('>');
       cputc(' ');