Added 386 platform to round and tests

.drone.yml

@@ -18,6 +18,33 @@ environment:
 workspace:
   path: /drone/src
 
+steps:
+  - name: test
+    image: golang:1.22-alpine3.19
+    commands:
+      - apk update
+      - apk add --no-cache git
+      - go test -p 1 -failfast -timeout 20m -cover -gcflags=-d=checkptr -v .
+---
+kind: pipeline
+type: docker
+name: from-source-386
+platform:
+  os: linux
+  arch: amd64
+
+environment:
+  GOPROXY: direct
+  GOARCH: 386
+  GO386: sse2
+  GOOS: linux
+  GOTRACEBACK: 2
+  GOEXPERIMENT: "cgocheck2,newinliner"
+  CGO_ENABLED: "0"
+
+workspace:
+  path: /drone/src
+
 steps:
   - name: test
     image: golang:1.22-alpine3.19

fpu/round_386.go

@@ -0,0 +1,20 @@
+//go:build 386
+
+package fpu
+
+// stmxcsr reads the MXCSR control and status register.
+//
+//go:noescape
+func stmxcsr(addr *uint32)
+
+// ldmxcsr writes to the MXCSR control and status register.
+//
+//go:noescape
+func ldmxcsr(addr *uint32)
+
+func setRoundingMode(mode uint8) {
+	var csr uint32
+	stmxcsr(&csr)
+	csr = (csr & (^uint32(0x6000))) | ((uint32(mode) & 3) << 13)
+	ldmxcsr(&csr)
+}

fpu/round_386.s

@@ -0,0 +1,13 @@
+#include "textflag.h"
+
+// stmxcsr reads the MXCSR control and status register.
+TEXT ·stmxcsr(SB),NOSPLIT|NOFRAME,$0-4
+	MOVL addr+0(FP), SI
+	STMXCSR (SI)
+	RET
+
+// ldmxcsr writes to the MXCSR control and status register.
+TEXT ·ldmxcsr(SB),NOSPLIT|NOFRAME,$0-4
+	MOVL addr+0(FP), SI
+	LDMXCSR (SI)
+	RET

fpu/round_generic.go

@@ -1,4 +1,4 @@
-//go:build !arm64 && !amd64
+//go:build !arm64 && !amd64 && !386
 
 package fpu