From d4ce962fe33f3eca8da0b4ab2b5a81cc5359b71f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sigrid=20Solveig=20Hafl=C3=ADnud=C3=B3ttir?=
 <sigrid@ftrv.se>
Date: Tue, 16 May 2023 15:39:00 +0000
Subject: 7l: use floating point immediates where possible

---
 sys/src/cmd/7l/asm.c    | 30 ++++++++++--------------------
 sys/src/cmd/7l/asmout.c | 11 +++++------
 2 files changed, 15 insertions(+), 26 deletions(-)

(limited to 'sys/src')

diff --git a/sys/src/cmd/7l/asm.c b/sys/src/cmd/7l/asm.c
index 0b3b444fa..399a037b2 100644
--- a/sys/src/cmd/7l/asm.c
+++ b/sys/src/cmd/7l/asm.c
@@ -589,27 +589,17 @@ datblk(long s, long n, int str)
 	write(cout, buf.dbuf, n);
 }
 
-static Ieee chipfloats[] = {
-	{0x00000000, 0x00000000}, /* 0 */
-	{0x00000000, 0x3ff00000}, /* 1 */
-	{0x00000000, 0x40000000}, /* 2 */
-	{0x00000000, 0x40080000}, /* 3 */
-	{0x00000000, 0x40100000}, /* 4 */
-	{0x00000000, 0x40140000}, /* 5 */
-	{0x00000000, 0x3fe00000}, /* .5 */
-	{0x00000000, 0x40240000}, /* 10 */
-};
-
 int
 chipfloat(Ieee *e)
 {
-	Ieee *p;
-	int n;
-
-	for(n = sizeof(chipfloats)/sizeof(chipfloats[0]); --n >= 0;){
-		p = &chipfloats[n];
-		if(p->l == e->l && p->h == e->h && 0)
-			return n;		/* TO DO: return imm8 encoding */
-	}
-	return -1;
+	int n, Bbbbbbbbb;
+
+	if(e->l != 0 || (e->h & 0xffffU) != 0)
+		return -1;
+	n = e->h >> 16;
+	Bbbbbbbbb = (n>>6) & 0x1ff;
+	if(Bbbbbbbbb != 0x100 && Bbbbbbbbb != 0xff)
+		return -1;
+	n = (n & 0x8000) >> 8 | (n & 0x7f);
+	return n;
 }
diff --git a/sys/src/cmd/7l/asmout.c b/sys/src/cmd/7l/asmout.c
index 9d29c30e3..342c35687 100644
--- a/sys/src/cmd/7l/asmout.c
+++ b/sys/src/cmd/7l/asmout.c
@@ -742,12 +742,11 @@ asmout(Prog *p, Optab *o)
 		o1 = oprrr(p->as);
 		if(p->from.type == D_FCONST) {
 			rf = chipfloat(p->from.ieee);
-			if(rf < 0 || 1){
+			if(rf < 0)
 				diag("invalid floating-point immediate\n%P", p);
-				rf = 0;
-			}
-			rf |= (1<<3);
-		} else
+			rf = rf<<(13-5) | 1<<(12-5);
+			o1 &= ~(0x10<<10);
+		}else
 			rf = p->from.reg;
 		rt = p->to.reg;
 		r = p->reg;
@@ -756,7 +755,7 @@ asmout(Prog *p, Optab *o)
 			rf = 0;
 		}else if(r == NREG)
 			r = rt;
-		o1 |= (rf << 16) | (r<<5) | rt;
+		o1 |= rf<<16 | r<<5 | rt;
 		break;
 
 	case 56:	/* floating point compare */
-- 
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