diff options
Diffstat (limited to 'noao/mtlocal/idsmtn/redflags.x')
| -rw-r--r-- | noao/mtlocal/idsmtn/redflags.x | 97 |
1 files changed, 97 insertions, 0 deletions
diff --git a/noao/mtlocal/idsmtn/redflags.x b/noao/mtlocal/idsmtn/redflags.x new file mode 100644 index 00000000..90c91a39 --- /dev/null +++ b/noao/mtlocal/idsmtn/redflags.x @@ -0,0 +1,97 @@ +include <mach.h> +include "idsmtn.h" + +define RED_FLAG_OFFSET 3 # Byte offset (starts at bit 17) +define DF_ORD_OFFSET 9 # Byte offset to df order value (bit 65) +define DFB 4 # Number of bytes per DF coefficient +define FIRST_BYTE 13 + +# REDUCTION_FLAGS -- Extract and interpret the reduction flags found in +# the IDS header. 9 flags are used: DF, SM, QF, DC, QD, EX, BS, CA, CO. +# Each flag is represented by a single bit in a varian 16-bit integer. +# If a flag is set, it's value = 0; unset flags = -1. If the QF flag is +# set, the order of the fitting polynomial must be unpacked. If the DF +# flag is set, the order of the fitting polynomial as well as the +# coefficients must be unpacked from the header. The location of the +# coefficients depends on the order of the fit. + +procedure reduction_flags (vn, ids) + +int vn[ARB] # Input buffer of IDS record - one byte per int +pointer ids # Pointer to ids header structure + +int flag_word, offset, byte_offset, op +real rtemp, tmp[MAX_NCOEFF] +errchk vn_rred + +begin + # Initialize flags to -1 + DF_FLAG(ids) = -1 + SM_FLAG(ids) = -1 + QF_FLAG(ids) = -1 + DC_FLAG(ids) = -1 + QD_FLAG(ids) = -1 + EX_FLAG(ids) = -1 + BS_FLAG(ids) = -1 + CA_FLAG(ids) = -1 + CO_FLAG(ids) = -1 + + # Unpack the flag_word from the header and determine flags. If a + # flag_bit is set, the corresponding flag is true and set = 0. + + flag_word = vn[RED_FLAG_OFFSET] * (2 ** 8) + vn[RED_FLAG_OFFSET+1] + + if (and (flag_word, 40B) != 0) + CO_FLAG(ids) = 0 + + if (and (flag_word, 100B) != 0) + CA_FLAG(ids) = 0 + + if (and (flag_word, 200B) != 0) + BS_FLAG(ids) = 0 + + if (and (flag_word, 400B) != 0) + EX_FLAG(ids) = 0 + + if (and (flag_word, 1000B) != 0) + QD_FLAG(ids) = 0 + + if (and (flag_word, 2000B) != 0) + DC_FLAG(ids) = 0 + + if (and (flag_word, 4000B) != 0) + # The qf_flag is set equal to the degree of the fitting polynomial. + # This value is stored in the lowest 5-bits of the flag word. + QF_FLAG(ids) = and (flag_word, 37B) + + if (and (flag_word, 10000B) != 0) + SM_FLAG(ids) = 0 + + # The df_flag is interpreted next: + if (and (flag_word, 20000B) != 0) { + # The degree of the fitting polynomial is written in 2wrd_vn_fp at + # the location of the first data pixel. The df_flag is set equal + # to the integer value of the polynomial degree. + + call vn_rred (vn, DF_ORD_OFFSET, rtemp, 1) + DF_FLAG(ids) = int (rtemp) + + # Now to unpack the coefficients. The coefficients have been + # written over pixels at the beginning and end of the IDS scan. + # The number and location of the overwritten pixels depends on + # the order of fit and values of NP1 and NP2. + + do op = 1, DF_FLAG(ids) { + offset = op + if (offset >= NP1(ids)) + # This coefficient must be stored at the end of scan + offset = offset + NP2(ids) - NP1(ids) + + byte_offset = FIRST_BYTE + ((offset - 1) * DFB) + call vn_rred (vn, byte_offset, tmp[op], 1) + } + + # Copy decoded coefficients into structure + call amovr (tmp, Memr[COEFF(ids)], DF_FLAG(ids)) + } +end |