cash.c

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/*
 * cash.c
 * Written by D'Arcy J.M. Cain
 * [email protected]
 * http://www.druid.net/darcy/
 *
 * Functions to allow input and output of money normally but store
 * and handle it as 64 bit ints
 *
 * A slightly modified version of this file and a discussion of the
 * workings can be found in the book "Software Solutions in C" by
 * Dale Schumacher, Academic Press, ISBN: 0-12-632360-7 except that
 * this version handles 64 bit numbers and so can hold values up to
 * $92,233,720,368,547,758.07.
 *
 * src/backend/utils/adt/cash.c
 */

#include "postgres.h"

#include <limits.h>
#include <ctype.h>
#include <math.h>
#include <locale.h>

#include "libpq/pqformat.h"
#include "utils/builtins.h"
#include "utils/cash.h"
#include "utils/int8.h"
#include "utils/numeric.h"
#include "utils/pg_locale.h"


/*************************************************************************
 * Private routines
 ************************************************************************/

static const char *
num_word(Cash value)
{
    static char buf[128];
    static const char *small[] = {
        "zero", "one", "two", "three", "four", "five", "six", "seven",
        "eight", "nine", "ten", "eleven", "twelve", "thirteen", "fourteen",
        "fifteen", "sixteen", "seventeen", "eighteen", "nineteen", "twenty",
        "thirty", "forty", "fifty", "sixty", "seventy", "eighty", "ninety"
    };
    const char **big = small + 18;
    int         tu = value % 100;

    /* deal with the simple cases first */
    if (value <= 20)
        return small[value];

    /* is it an even multiple of 100? */
    if (!tu)
    {
        sprintf(buf, "%s hundred", small[value / 100]);
        return buf;
    }

    /* more than 99? */
    if (value > 99)
    {
        /* is it an even multiple of 10 other than 10? */
        if (value % 10 == 0 && tu > 10)
            sprintf(buf, "%s hundred %s",
                    small[value / 100], big[tu / 10]);
        else if (tu < 20)
            sprintf(buf, "%s hundred and %s",
                    small[value / 100], small[tu]);
        else
            sprintf(buf, "%s hundred %s %s",
                    small[value / 100], big[tu / 10], small[tu % 10]);
    }
    else
    {
        /* is it an even multiple of 10 other than 10? */
        if (value % 10 == 0 && tu > 10)
            sprintf(buf, "%s", big[tu / 10]);
        else if (tu < 20)
            sprintf(buf, "%s", small[tu]);
        else
            sprintf(buf, "%s %s", big[tu / 10], small[tu % 10]);
    }

    return buf;
}   /* num_word() */

/* cash_in()
 * Convert a string to a cash data type.
 * Format is [$]###[,]###[.##]
 * Examples: 123.45 $123.45 $123,456.78
 *
 */
Datum
cash_in(PG_FUNCTION_ARGS)
{
    char       *str = PG_GETARG_CSTRING(0);
    Cash        result;
    Cash        value = 0;
    Cash        dec = 0;
    Cash        sgn = 1;
    bool        seen_dot = false;
    const char *s = str;
    int         fpoint;
    char        dsymbol;
    const char *ssymbol,
               *psymbol,
               *nsymbol,
               *csymbol;
    struct lconv *lconvert = PGLC_localeconv();

    /*
     * frac_digits will be CHAR_MAX in some locales, notably C.  However, just
     * testing for == CHAR_MAX is risky, because of compilers like gcc that
     * "helpfully" let you alter the platform-standard definition of whether
     * char is signed or not.  If we are so unfortunate as to get compiled
     * with a nonstandard -fsigned-char or -funsigned-char switch, then our
     * idea of CHAR_MAX will not agree with libc's. The safest course is not
     * to test for CHAR_MAX at all, but to impose a range check for plausible
     * frac_digits values.
     */
    fpoint = lconvert->frac_digits;
    if (fpoint < 0 || fpoint > 10)
        fpoint = 2;             /* best guess in this case, I think */

    /* we restrict dsymbol to be a single byte, but not the other symbols */
    if (*lconvert->mon_decimal_point != '\0' &&
        lconvert->mon_decimal_point[1] == '\0')
        dsymbol = *lconvert->mon_decimal_point;
    else
        dsymbol = '.';
    if (*lconvert->mon_thousands_sep != '\0')
        ssymbol = lconvert->mon_thousands_sep;
    else    /* ssymbol should not equal dsymbol */
        ssymbol = (dsymbol != ',') ? "," : ".";
    csymbol = (*lconvert->currency_symbol != '\0') ? lconvert->currency_symbol : "$";
    psymbol = (*lconvert->positive_sign != '\0') ? lconvert->positive_sign : "+";
    nsymbol = (*lconvert->negative_sign != '\0') ? lconvert->negative_sign : "-";

#ifdef CASHDEBUG
    printf("cashin- precision '%d'; decimal '%c'; thousands '%s'; currency '%s'; positive '%s'; negative '%s'\n",
           fpoint, dsymbol, ssymbol, csymbol, psymbol, nsymbol);
#endif

    /* we need to add all sorts of checking here.  For now just */
    /* strip all leading whitespace and any leading currency symbol */
    while (isspace((unsigned char) *s))
        s++;
    if (strncmp(s, csymbol, strlen(csymbol)) == 0)
        s += strlen(csymbol);
    while (isspace((unsigned char) *s))
        s++;

#ifdef CASHDEBUG
    printf("cashin- string is '%s'\n", s);
#endif

    /* a leading minus or paren signifies a negative number */
    /* again, better heuristics needed */
    /* XXX - doesn't properly check for balanced parens - djmc */
    if (strncmp(s, nsymbol, strlen(nsymbol)) == 0)
    {
        sgn = -1;
        s += strlen(nsymbol);
    }
    else if (*s == '(')
    {
        sgn = -1;
        s++;
    }
    else if (strncmp(s, psymbol, strlen(psymbol)) == 0)
        s += strlen(psymbol);

#ifdef CASHDEBUG
    printf("cashin- string is '%s'\n", s);
#endif

    /* allow whitespace and currency symbol after the sign, too */
    while (isspace((unsigned char) *s))
        s++;
    if (strncmp(s, csymbol, strlen(csymbol)) == 0)
        s += strlen(csymbol);
    while (isspace((unsigned char) *s))
        s++;

#ifdef CASHDEBUG
    printf("cashin- string is '%s'\n", s);
#endif

    for (; *s; s++)
    {
        /* we look for digits as long as we have found less */
        /* than the required number of decimal places */
        if (isdigit((unsigned char) *s) && (!seen_dot || dec < fpoint))
        {
            value = (value * 10) + (*s - '0');

            if (seen_dot)
                dec++;
        }
        /* decimal point? then start counting fractions... */
        else if (*s == dsymbol && !seen_dot)
        {
            seen_dot = true;
        }
        /* ignore if "thousands" separator, else we're done */
        else if (strncmp(s, ssymbol, strlen(ssymbol)) == 0)
            s += strlen(ssymbol) - 1;
        else
            break;
    }

    /* round off if there's another digit */
    if (isdigit((unsigned char) *s) && *s >= '5')
        value++;

    /* adjust for less than required decimal places */
    for (; dec < fpoint; dec++)
        value *= 10;

    /*
     * should only be trailing digits followed by whitespace, right paren,
     * trailing sign, and/or trailing currency symbol
     */
    while (isdigit((unsigned char) *s))
        s++;

    while (*s)
    {
        if (isspace((unsigned char) *s) || *s == ')')
            s++;
        else if (strncmp(s, nsymbol, strlen(nsymbol)) == 0)
        {
            sgn = -1;
            s += strlen(nsymbol);
        }
        else if (strncmp(s, psymbol, strlen(psymbol)) == 0)
            s += strlen(psymbol);
        else if (strncmp(s, csymbol, strlen(csymbol)) == 0)
            s += strlen(csymbol);
        else
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                     errmsg("invalid input syntax for type money: \"%s\"",
                            str)));
    }

    result = value * sgn;

#ifdef CASHDEBUG
    printf("cashin- result is " INT64_FORMAT "\n", result);
#endif

    PG_RETURN_CASH(result);
}


/* cash_out()
 * Function to convert cash to a dollars and cents representation, using
 * the lc_monetary locale's formatting.
 */
Datum
cash_out(PG_FUNCTION_ARGS)
{
    Cash        value = PG_GETARG_CASH(0);
    char       *result;
    char        buf[128];
    char       *bufptr;
    int         digit_pos;
    int         points,
                mon_group;
    char        dsymbol;
    const char *ssymbol,
               *csymbol,
               *signsymbol;
    char        sign_posn,
                cs_precedes,
                sep_by_space;
    struct lconv *lconvert = PGLC_localeconv();

    /* see comments about frac_digits in cash_in() */
    points = lconvert->frac_digits;
    if (points < 0 || points > 10)
        points = 2;             /* best guess in this case, I think */

    /*
     * As with frac_digits, must apply a range check to mon_grouping to avoid
     * being fooled by variant CHAR_MAX values.
     */
    mon_group = *lconvert->mon_grouping;
    if (mon_group <= 0 || mon_group > 6)
        mon_group = 3;

    /* we restrict dsymbol to be a single byte, but not the other symbols */
    if (*lconvert->mon_decimal_point != '\0' &&
        lconvert->mon_decimal_point[1] == '\0')
        dsymbol = *lconvert->mon_decimal_point;
    else
        dsymbol = '.';
    if (*lconvert->mon_thousands_sep != '\0')
        ssymbol = lconvert->mon_thousands_sep;
    else    /* ssymbol should not equal dsymbol */
        ssymbol = (dsymbol != ',') ? "," : ".";
    csymbol = (*lconvert->currency_symbol != '\0') ? lconvert->currency_symbol : "$";

    if (value < 0)
    {
        /* make the amount positive for digit-reconstruction loop */
        value = -value;
        /* set up formatting data */
        signsymbol = (*lconvert->negative_sign != '\0') ? lconvert->negative_sign : "-";
        sign_posn = lconvert->n_sign_posn;
        cs_precedes = lconvert->n_cs_precedes;
        sep_by_space = lconvert->n_sep_by_space;
    }
    else
    {
        signsymbol = lconvert->positive_sign;
        sign_posn = lconvert->p_sign_posn;
        cs_precedes = lconvert->p_cs_precedes;
        sep_by_space = lconvert->p_sep_by_space;
    }

    /* we build the digits+decimal-point+sep string right-to-left in buf[] */
    bufptr = buf + sizeof(buf) - 1;
    *bufptr = '\0';

    /*
     * Generate digits till there are no non-zero digits left and we emitted
     * at least one to the left of the decimal point.  digit_pos is the
     * current digit position, with zero as the digit just left of the decimal
     * point, increasing to the right.
     */
    digit_pos = points;
    do
    {
        if (points && digit_pos == 0)
        {
            /* insert decimal point, but not if value cannot be fractional */
            *(--bufptr) = dsymbol;
        }
        else if (digit_pos < 0 && (digit_pos % mon_group) == 0)
        {
            /* insert thousands sep, but only to left of radix point */
            bufptr -= strlen(ssymbol);
            memcpy(bufptr, ssymbol, strlen(ssymbol));
        }

        *(--bufptr) = ((uint64) value % 10) + '0';
        value = ((uint64) value) / 10;
        digit_pos--;
    } while (value || digit_pos >= 0);

    /*----------
     * Now, attach currency symbol and sign symbol in the correct order.
     *
     * The POSIX spec defines these values controlling this code:
     *
     * p/n_sign_posn:
     *  0   Parentheses enclose the quantity and the currency_symbol.
     *  1   The sign string precedes the quantity and the currency_symbol.
     *  2   The sign string succeeds the quantity and the currency_symbol.
     *  3   The sign string precedes the currency_symbol.
     *  4   The sign string succeeds the currency_symbol.
     *
     * p/n_cs_precedes: 0 means currency symbol after value, else before it.
     *
     * p/n_sep_by_space:
     *  0   No <space> separates the currency symbol and value.
     *  1   If the currency symbol and sign string are adjacent, a <space>
     *      separates them from the value; otherwise, a <space> separates
     *      the currency symbol from the value.
     *  2   If the currency symbol and sign string are adjacent, a <space>
     *      separates them; otherwise, a <space> separates the sign string
     *      from the value.
     *----------
     */
    result = palloc(strlen(bufptr) + strlen(csymbol) + strlen(signsymbol) + 4);

    switch (sign_posn)
    {
        case 0:
            if (cs_precedes)
                sprintf(result, "(%s%s%s)",
                        csymbol,
                        (sep_by_space == 1) ? " " : "",
                        bufptr);
            else
                sprintf(result, "(%s%s%s)",
                        bufptr,
                        (sep_by_space == 1) ? " " : "",
                        csymbol);
            break;
        case 1:
        default:
            if (cs_precedes)
                sprintf(result, "%s%s%s%s%s",
                        signsymbol,
                        (sep_by_space == 2) ? " " : "",
                        csymbol,
                        (sep_by_space == 1) ? " " : "",
                        bufptr);
            else
                sprintf(result, "%s%s%s%s%s",
                        signsymbol,
                        (sep_by_space == 2) ? " " : "",
                        bufptr,
                        (sep_by_space == 1) ? " " : "",
                        csymbol);
            break;
        case 2:
            if (cs_precedes)
                sprintf(result, "%s%s%s%s%s",
                        csymbol,
                        (sep_by_space == 1) ? " " : "",
                        bufptr,
                        (sep_by_space == 2) ? " " : "",
                        signsymbol);
            else
                sprintf(result, "%s%s%s%s%s",
                        bufptr,
                        (sep_by_space == 1) ? " " : "",
                        csymbol,
                        (sep_by_space == 2) ? " " : "",
                        signsymbol);
            break;
        case 3:
            if (cs_precedes)
                sprintf(result, "%s%s%s%s%s",
                        signsymbol,
                        (sep_by_space == 2) ? " " : "",
                        csymbol,
                        (sep_by_space == 1) ? " " : "",
                        bufptr);
            else
                sprintf(result, "%s%s%s%s%s",
                        bufptr,
                        (sep_by_space == 1) ? " " : "",
                        signsymbol,
                        (sep_by_space == 2) ? " " : "",
                        csymbol);
            break;
        case 4:
            if (cs_precedes)
                sprintf(result, "%s%s%s%s%s",
                        csymbol,
                        (sep_by_space == 2) ? " " : "",
                        signsymbol,
                        (sep_by_space == 1) ? " " : "",
                        bufptr);
            else
                sprintf(result, "%s%s%s%s%s",
                        bufptr,
                        (sep_by_space == 1) ? " " : "",
                        csymbol,
                        (sep_by_space == 2) ? " " : "",
                        signsymbol);
            break;
    }

    PG_RETURN_CSTRING(result);
}

/*
 *      cash_recv           - converts external binary format to cash
 */
Datum
cash_recv(PG_FUNCTION_ARGS)
{
    StringInfo  buf = (StringInfo) PG_GETARG_POINTER(0);

    PG_RETURN_CASH((Cash) pq_getmsgint64(buf));
}

/*
 *      cash_send           - converts cash to binary format
 */
Datum
cash_send(PG_FUNCTION_ARGS)
{
    Cash        arg1 = PG_GETARG_CASH(0);
    StringInfoData buf;

    pq_begintypsend(&buf);
    pq_sendint64(&buf, arg1);
    PG_RETURN_BYTEA_P(pq_endtypsend(&buf));
}

/*
 * Comparison functions
 */

Datum
cash_eq(PG_FUNCTION_ARGS)
{
    Cash        c1 = PG_GETARG_CASH(0);
    Cash        c2 = PG_GETARG_CASH(1);

    PG_RETURN_BOOL(c1 == c2);
}

Datum
cash_ne(PG_FUNCTION_ARGS)
{
    Cash        c1 = PG_GETARG_CASH(0);
    Cash        c2 = PG_GETARG_CASH(1);

    PG_RETURN_BOOL(c1 != c2);
}

Datum
cash_lt(PG_FUNCTION_ARGS)
{
    Cash        c1 = PG_GETARG_CASH(0);
    Cash        c2 = PG_GETARG_CASH(1);

    PG_RETURN_BOOL(c1 < c2);
}

Datum
cash_le(PG_FUNCTION_ARGS)
{
    Cash        c1 = PG_GETARG_CASH(0);
    Cash        c2 = PG_GETARG_CASH(1);

    PG_RETURN_BOOL(c1 <= c2);
}

Datum
cash_gt(PG_FUNCTION_ARGS)
{
    Cash        c1 = PG_GETARG_CASH(0);
    Cash        c2 = PG_GETARG_CASH(1);

    PG_RETURN_BOOL(c1 > c2);
}

Datum
cash_ge(PG_FUNCTION_ARGS)
{
    Cash        c1 = PG_GETARG_CASH(0);
    Cash        c2 = PG_GETARG_CASH(1);

    PG_RETURN_BOOL(c1 >= c2);
}

Datum
cash_cmp(PG_FUNCTION_ARGS)
{
    Cash        c1 = PG_GETARG_CASH(0);
    Cash        c2 = PG_GETARG_CASH(1);

    if (c1 > c2)
        PG_RETURN_INT32(1);
    else if (c1 == c2)
        PG_RETURN_INT32(0);
    else
        PG_RETURN_INT32(-1);
}


/* cash_pl()
 * Add two cash values.
 */
Datum
cash_pl(PG_FUNCTION_ARGS)
{
    Cash        c1 = PG_GETARG_CASH(0);
    Cash        c2 = PG_GETARG_CASH(1);
    Cash        result;

    result = c1 + c2;

    PG_RETURN_CASH(result);
}


/* cash_mi()
 * Subtract two cash values.
 */
Datum
cash_mi(PG_FUNCTION_ARGS)
{
    Cash        c1 = PG_GETARG_CASH(0);
    Cash        c2 = PG_GETARG_CASH(1);
    Cash        result;

    result = c1 - c2;

    PG_RETURN_CASH(result);
}


/* cash_div_cash()
 * Divide cash by cash, returning float8.
 */
Datum
cash_div_cash(PG_FUNCTION_ARGS)
{
    Cash        dividend = PG_GETARG_CASH(0);
    Cash        divisor = PG_GETARG_CASH(1);
    float8      quotient;

    if (divisor == 0)
        ereport(ERROR,
                (errcode(ERRCODE_DIVISION_BY_ZERO),
                 errmsg("division by zero")));

    quotient = (float8) dividend / (float8) divisor;
    PG_RETURN_FLOAT8(quotient);
}


/* cash_mul_flt8()
 * Multiply cash by float8.
 */
Datum
cash_mul_flt8(PG_FUNCTION_ARGS)
{
    Cash        c = PG_GETARG_CASH(0);
    float8      f = PG_GETARG_FLOAT8(1);
    Cash        result;

    result = c * f;
    PG_RETURN_CASH(result);
}


/* flt8_mul_cash()
 * Multiply float8 by cash.
 */
Datum
flt8_mul_cash(PG_FUNCTION_ARGS)
{
    float8      f = PG_GETARG_FLOAT8(0);
    Cash        c = PG_GETARG_CASH(1);
    Cash        result;

    result = f * c;
    PG_RETURN_CASH(result);
}


/* cash_div_flt8()
 * Divide cash by float8.
 */
Datum
cash_div_flt8(PG_FUNCTION_ARGS)
{
    Cash        c = PG_GETARG_CASH(0);
    float8      f = PG_GETARG_FLOAT8(1);
    Cash        result;

    if (f == 0.0)
        ereport(ERROR,
                (errcode(ERRCODE_DIVISION_BY_ZERO),
                 errmsg("division by zero")));

    result = rint(c / f);
    PG_RETURN_CASH(result);
}


/* cash_mul_flt4()
 * Multiply cash by float4.
 */
Datum
cash_mul_flt4(PG_FUNCTION_ARGS)
{
    Cash        c = PG_GETARG_CASH(0);
    float4      f = PG_GETARG_FLOAT4(1);
    Cash        result;

    result = c * f;
    PG_RETURN_CASH(result);
}


/* flt4_mul_cash()
 * Multiply float4 by cash.
 */
Datum
flt4_mul_cash(PG_FUNCTION_ARGS)
{
    float4      f = PG_GETARG_FLOAT4(0);
    Cash        c = PG_GETARG_CASH(1);
    Cash        result;

    result = f * c;
    PG_RETURN_CASH(result);
}


/* cash_div_flt4()
 * Divide cash by float4.
 *
 */
Datum
cash_div_flt4(PG_FUNCTION_ARGS)
{
    Cash        c = PG_GETARG_CASH(0);
    float4      f = PG_GETARG_FLOAT4(1);
    Cash        result;

    if (f == 0.0)
        ereport(ERROR,
                (errcode(ERRCODE_DIVISION_BY_ZERO),
                 errmsg("division by zero")));

    result = rint(c / f);
    PG_RETURN_CASH(result);
}


/* cash_mul_int8()
 * Multiply cash by int8.
 */
Datum
cash_mul_int8(PG_FUNCTION_ARGS)
{
    Cash        c = PG_GETARG_CASH(0);
    int64       i = PG_GETARG_INT64(1);
    Cash        result;

    result = c * i;
    PG_RETURN_CASH(result);
}


/* int8_mul_cash()
 * Multiply int8 by cash.
 */
Datum
int8_mul_cash(PG_FUNCTION_ARGS)
{
    int64       i = PG_GETARG_INT64(0);
    Cash        c = PG_GETARG_CASH(1);
    Cash        result;

    result = i * c;
    PG_RETURN_CASH(result);
}

/* cash_div_int8()
 * Divide cash by 8-byte integer.
 */
Datum
cash_div_int8(PG_FUNCTION_ARGS)
{
    Cash        c = PG_GETARG_CASH(0);
    int64       i = PG_GETARG_INT64(1);
    Cash        result;

    if (i == 0)
        ereport(ERROR,
                (errcode(ERRCODE_DIVISION_BY_ZERO),
                 errmsg("division by zero")));

    result = rint(c / i);

    PG_RETURN_CASH(result);
}


/* cash_mul_int4()
 * Multiply cash by int4.
 */
Datum
cash_mul_int4(PG_FUNCTION_ARGS)
{
    Cash        c = PG_GETARG_CASH(0);
    int32       i = PG_GETARG_INT32(1);
    Cash        result;

    result = c * i;
    PG_RETURN_CASH(result);
}


/* int4_mul_cash()
 * Multiply int4 by cash.
 */
Datum
int4_mul_cash(PG_FUNCTION_ARGS)
{
    int32       i = PG_GETARG_INT32(0);
    Cash        c = PG_GETARG_CASH(1);
    Cash        result;

    result = i * c;
    PG_RETURN_CASH(result);
}


/* cash_div_int4()
 * Divide cash by 4-byte integer.
 *
 */
Datum
cash_div_int4(PG_FUNCTION_ARGS)
{
    Cash        c = PG_GETARG_CASH(0);
    int32       i = PG_GETARG_INT32(1);
    Cash        result;

    if (i == 0)
        ereport(ERROR,
                (errcode(ERRCODE_DIVISION_BY_ZERO),
                 errmsg("division by zero")));

    result = rint(c / i);

    PG_RETURN_CASH(result);
}


/* cash_mul_int2()
 * Multiply cash by int2.
 */
Datum
cash_mul_int2(PG_FUNCTION_ARGS)
{
    Cash        c = PG_GETARG_CASH(0);
    int16       s = PG_GETARG_INT16(1);
    Cash        result;

    result = c * s;
    PG_RETURN_CASH(result);
}

/* int2_mul_cash()
 * Multiply int2 by cash.
 */
Datum
int2_mul_cash(PG_FUNCTION_ARGS)
{
    int16       s = PG_GETARG_INT16(0);
    Cash        c = PG_GETARG_CASH(1);
    Cash        result;

    result = s * c;
    PG_RETURN_CASH(result);
}

/* cash_div_int2()
 * Divide cash by int2.
 *
 */
Datum
cash_div_int2(PG_FUNCTION_ARGS)
{
    Cash        c = PG_GETARG_CASH(0);
    int16       s = PG_GETARG_INT16(1);
    Cash        result;

    if (s == 0)
        ereport(ERROR,
                (errcode(ERRCODE_DIVISION_BY_ZERO),
                 errmsg("division by zero")));

    result = rint(c / s);
    PG_RETURN_CASH(result);
}

/* cashlarger()
 * Return larger of two cash values.
 */
Datum
cashlarger(PG_FUNCTION_ARGS)
{
    Cash        c1 = PG_GETARG_CASH(0);
    Cash        c2 = PG_GETARG_CASH(1);
    Cash        result;

    result = (c1 > c2) ? c1 : c2;

    PG_RETURN_CASH(result);
}

/* cashsmaller()
 * Return smaller of two cash values.
 */
Datum
cashsmaller(PG_FUNCTION_ARGS)
{
    Cash        c1 = PG_GETARG_CASH(0);
    Cash        c2 = PG_GETARG_CASH(1);
    Cash        result;

    result = (c1 < c2) ? c1 : c2;

    PG_RETURN_CASH(result);
}

/* cash_words()
 * This converts a int4 as well but to a representation using words
 * Obviously way North American centric - sorry
 */
Datum
cash_words(PG_FUNCTION_ARGS)
{
    Cash        value = PG_GETARG_CASH(0);
    uint64      val;
    char        buf[256];
    char       *p = buf;
    Cash        m0;
    Cash        m1;
    Cash        m2;
    Cash        m3;
    Cash        m4;
    Cash        m5;
    Cash        m6;

    /* work with positive numbers */
    if (value < 0)
    {
        value = -value;
        strcpy(buf, "minus ");
        p += 6;
    }
    else
        buf[0] = '\0';

    /* Now treat as unsigned, to avoid trouble at INT_MIN */
    val = (uint64) value;

    m0 = val % INT64CONST(100); /* cents */
    m1 = (val / INT64CONST(100)) % 1000;        /* hundreds */
    m2 = (val / INT64CONST(100000)) % 1000;     /* thousands */
    m3 = (val / INT64CONST(100000000)) % 1000;  /* millions */
    m4 = (val / INT64CONST(100000000000)) % 1000;       /* billions */
    m5 = (val / INT64CONST(100000000000000)) % 1000;    /* trillions */
    m6 = (val / INT64CONST(100000000000000000)) % 1000; /* quadrillions */

    if (m6)
    {
        strcat(buf, num_word(m6));
        strcat(buf, " quadrillion ");
    }

    if (m5)
    {
        strcat(buf, num_word(m5));
        strcat(buf, " trillion ");
    }

    if (m4)
    {
        strcat(buf, num_word(m4));
        strcat(buf, " billion ");
    }

    if (m3)
    {
        strcat(buf, num_word(m3));
        strcat(buf, " million ");
    }

    if (m2)
    {
        strcat(buf, num_word(m2));
        strcat(buf, " thousand ");
    }

    if (m1)
        strcat(buf, num_word(m1));

    if (!*p)
        strcat(buf, "zero");

    strcat(buf, (val / 100) == 1 ? " dollar and " : " dollars and ");
    strcat(buf, num_word(m0));
    strcat(buf, m0 == 1 ? " cent" : " cents");

    /* capitalize output */
    buf[0] = pg_toupper((unsigned char) buf[0]);

    /* return as text datum */
    PG_RETURN_TEXT_P(cstring_to_text(buf));
}


/* cash_numeric()
 * Convert cash to numeric.
 */
Datum
cash_numeric(PG_FUNCTION_ARGS)
{
    Cash        money = PG_GETARG_CASH(0);
    Numeric     result;
    int         fpoint;
    int64       scale;
    int         i;
    Datum       amount;
    Datum       numeric_scale;
    Datum       quotient;
    struct lconv *lconvert = PGLC_localeconv();

    /* see comments about frac_digits in cash_in() */
    fpoint = lconvert->frac_digits;
    if (fpoint < 0 || fpoint > 10)
        fpoint = 2;

    /* compute required scale factor */
    scale = 1;
    for (i = 0; i < fpoint; i++)
        scale *= 10;

    /* form the result as money / scale */
    amount = DirectFunctionCall1(int8_numeric, Int64GetDatum(money));
    numeric_scale = DirectFunctionCall1(int8_numeric, Int64GetDatum(scale));
    quotient = DirectFunctionCall2(numeric_div, amount, numeric_scale);

    /* forcibly round to exactly the intended number of digits */
    result = DatumGetNumeric(DirectFunctionCall2(numeric_round,
                                                 quotient,
                                                 Int32GetDatum(fpoint)));

    PG_RETURN_NUMERIC(result);
}

/* numeric_cash()
 * Convert numeric to cash.
 */
Datum
numeric_cash(PG_FUNCTION_ARGS)
{
    Datum       amount = PG_GETARG_DATUM(0);
    Cash        result;
    int         fpoint;
    int64       scale;
    int         i;
    Datum       numeric_scale;
    struct lconv *lconvert = PGLC_localeconv();

    /* see comments about frac_digits in cash_in() */
    fpoint = lconvert->frac_digits;
    if (fpoint < 0 || fpoint > 10)
        fpoint = 2;

    /* compute required scale factor */
    scale = 1;
    for (i = 0; i < fpoint; i++)
        scale *= 10;

    /* multiply the input amount by scale factor */
    numeric_scale = DirectFunctionCall1(int8_numeric, Int64GetDatum(scale));
    amount = DirectFunctionCall2(numeric_mul, amount, numeric_scale);

    /* note that numeric_int8 will round to nearest integer for us */
    result = DatumGetInt64(DirectFunctionCall1(numeric_int8, amount));

    PG_RETURN_CASH(result);
}

/* int4_cash()
 * Convert int4 (int) to cash
 */
Datum
int4_cash(PG_FUNCTION_ARGS)
{
    int32       amount = PG_GETARG_INT32(0);
    Cash        result;
    int         fpoint;
    int64       scale;
    int         i;
    struct lconv *lconvert = PGLC_localeconv();

    /* see comments about frac_digits in cash_in() */
    fpoint = lconvert->frac_digits;
    if (fpoint < 0 || fpoint > 10)
        fpoint = 2;

    /* compute required scale factor */
    scale = 1;
    for (i = 0; i < fpoint; i++)
        scale *= 10;

    /* compute amount * scale, checking for overflow */
    result = DatumGetInt64(DirectFunctionCall2(int8mul, Int64GetDatum(amount),
                                               Int64GetDatum(scale)));

    PG_RETURN_CASH(result);
}

/* int8_cash()
 * Convert int8 (bigint) to cash
 */
Datum
int8_cash(PG_FUNCTION_ARGS)
{
    int64       amount = PG_GETARG_INT64(0);
    Cash        result;
    int         fpoint;
    int64       scale;
    int         i;
    struct lconv *lconvert = PGLC_localeconv();

    /* see comments about frac_digits in cash_in() */
    fpoint = lconvert->frac_digits;
    if (fpoint < 0 || fpoint > 10)
        fpoint = 2;

    /* compute required scale factor */
    scale = 1;
    for (i = 0; i < fpoint; i++)
        scale *= 10;

    /* compute amount * scale, checking for overflow */
    result = DatumGetInt64(DirectFunctionCall2(int8mul, Int64GetDatum(amount),
                                               Int64GetDatum(scale)));

    PG_RETURN_CASH(result);
}