add fpga_test

tos/fpga_test/sources/printf_helper.S

@@ -0,0 +1,38 @@
+/*
+ * printf_helper.S
+ *
+ * assembler trampoline to let printf (compiled -mpcrel) indirectly reference __MBAR
+ *
+ * This file is part of BaS_gcc.
+ *
+ * BaS_gcc is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * BaS_gcc is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with BaS_gcc.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Copyright 2010 - 2012 F. Aschwanden
+ * Copyright 2011 - 2012 V. Riviere
+ * Copyright 2012 - 2025 M. Froeschle
+ */
+
+
+	.globl	printf_helper
+
+printf_helper:
+	.extern	__MBAR
+
+.wait_txready:
+	move.w	__MBAR+0x8604,d2		// PSCSCR0 status register
+	btst	#10,d2				// space left in TX fifo?
+	beq.s	.wait_txready			// no, loop
+	lea	__MBAR+0x860C,a0		// PSCSTB0 transmitter buffer register
+	move.b	d0,(a0)				// send byte
+	rts