1 files changed, 126 insertions, 0 deletions
diff --git a/noao/mtlocal/idsmtn/rvarian.x b/noao/mtlocal/idsmtn/rvarian.x
new file mode 100644
index 00000000..ebfd7c4b
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+++ b/noao/mtlocal/idsmtn/rvarian.x
@@ -0,0 +1,126 @@
+include	<error.h>
+include	<mach.h>
+include	"idsmtn.h"
+
+# UNPK_VN_ID -- Unpack an ID string from an array of FORTH ascii characters,
+# one 7-bit character per byte.  The first byte contains the character
+# count for the string.  
+
+procedure unpk_vn_id (varian, offset, output_string)
+
+int	varian[ARB]		# Array with one byte per int
+int	offset			# Word offset to first character to be unpacked
+char	output_string[SZ_IDS_ID]     # Output array - one character per element
+
+pointer	sp, id
+int	nchars_id
+
+begin
+	call smark (sp)
+	nchars_id = min (varian[offset], SZ_IDS_ID-1)
+	call salloc (id, nchars_id, TY_CHAR)
+
+	call achtic (varian[offset+1], Memc[id], nchars_id)
+	call strcpy (Memc[id], output_string, nchars_id)
+
+	call sfree (sp)
+end
+
+
+# VN_RRAW -- Read Varian long (32-bit) integers from a packed bit array.
+# Raw pixels are written as Varian long integers.  Each  pixel is 
+# 32-bits with bit 1 least significant, bit 16 unused and bit 32 the
+# sign bit.  The bits are extracted and reassembled to form a real array of 
+# IDS pixels, one pixel per array element.
+
+procedure vn_rraw (varian, offset, pixels, nwords)
+
+int	varian[ARB]		# Pointer to array of packed IDS record
+int	offset			# Word offset to first word to unpack
+real	pixels[nwords]		# Output array of unpacked IDS pixels
+int	nwords			# Number of values to unpack
+
+int	ip, op, bytes[4], int_value
+
+include	"lut.com"
+
+begin
+	ip = offset
+	for (op = 1; op <= nwords; op = op + 1) {
+
+	    call amovi (varian[ip], bytes, 4)
+
+	    if (bytes[1] < 127)
+	        int_value = bytes[4] + (bytes[3] * (2 ** 8)) + (bytes[2] * 
+	            (2 ** 15)) + (bytes[1] * (2 ** 23))
+	    else {
+		bytes[1] = neg_lut8[bytes[1]] * (2 ** 23)
+		bytes[2] = neg_lut8[bytes[2]] * (2 ** 15)
+		bytes[3] = neg_lut7[bytes[3]] * (2 ** 8)
+		bytes[4] = neg_lut8[bytes[4]]
+		int_value = -1 * (bytes[1] + bytes[2] + bytes[3] + bytes[4] + 1)
+	    }
+
+	    pixels[op] = real (int_value)
+	    ip = ip + 4
+	}
+end
+
+
+# VN_RRED -- Read 32-bit floating point pixels from a packed bit array.  
+# The values are written in special (Jan Schwitters) 2 word Varian floating 
+# point.  Reduced pixels are written in this format.
+
+procedure vn_rred (varian, offset, pixels, nwords)
+
+int	varian[ARB]		# Array of packed varian values
+int	offset			# Word offset to first value to unpack
+real	pixels[nwords]		# Output array of unpacked values
+int	nwords			# Number of values to unpack
+
+int	ip, op, mantissa, exp, bytes[4]
+
+include	"lut.com"
+include	"powersof2.com"
+
+begin
+	ip = offset
+
+	do op = 1, nwords {
+
+	    call amovi (varian[ip], bytes, 4)
+
+	    if (mod (bytes[1], 2) == 0)
+	        mantissa = bytes[4] + (bytes[3] * (2**8)) + (bytes[2] * (2**15))
+	    else {
+		bytes[4] = neg_lut8[bytes[4]]
+		bytes[3] = neg_lut7[bytes[3]] * (2 ** 8)
+		bytes[2] = neg_lut8[bytes[2]] * (2 ** 15)
+		mantissa = -1 * (bytes[4] + bytes[3] + bytes[2] + 1)
+	    }
+
+	    # Divide out mantissa sign bit
+	    exp = bytes[1]/2
+	    if (bytes[1] > 127)
+		exp = -1 * (neg_lut6[exp] + 1)
+
+	    # Reconstruct the floating point number as a SPP real.  Powers of
+	    # two are stored in the tbl[] array where 2 ** n = tbl[n + 129].
+	    # The mantissa is divided by 2 ** 23 to move the binary point
+	    # above bit 23.
+
+	    exp = exp + 129 - 23
+
+    	    if (exp <= 0)
+	        pixels[op] = 0.0
+
+            else if (exp > 255) 
+	        pixels[op] = MAX_REAL
+
+            else if (exp > 0 && exp <= 255)
+	        pixels[op] = real (mantissa) * tbl [exp]
+
+	    # Increment the input pointer for the next word to be unpacked
+	    ip = ip + 4
+	}
+end