[U-Boot] [PATCH V4 11/11] parse_helper: add expression evaluation

[Liu Hui-R64343]

>-----Original Message-----
>From: Troy Kisky [mailto:troy.kisky at boundarydevices.com]
>Sent: Wednesday, November 28, 2012 9:32 AM
>To: sbabic at denx.de
>Cc: dirk.behme at googlemail.com; u-boot at lists.denx.de; Liu Hui-R64343;
>festevam at gmail.com; Troy Kisky
>Subject: [PATCH V4 11/11] parse_helper: add expression evaluation
>
>Basic expressions with order precedence is now supported.
>ie. (----3 + ((1+2*3)/--2 + --5 *(8/4))) is 16.
>
>Signed-off-by: Troy Kisky <troy.kisky at boundarydevices.com>

Acked-by: Jason Liu <r64343 at freescale.com>

>---
> tools/parse_helper.c |  172
>+++++++++++++++++++++++++++++++++++++++++++++++---
> 1 file changed, 162 insertions(+), 10 deletions(-)
>
>diff --git a/tools/parse_helper.c b/tools/parse_helper.c index
>0a5c5f6..50be832 100644
>--- a/tools/parse_helper.c
>+++ b/tools/parse_helper.c
>@@ -97,20 +97,172 @@ int ph_skip_comma(struct parse_helper *ph)
> 	}
> }
>
>+static const char precedence[] = {
>+	/* (  +  -  *  /  &  ^  |  ) */
>+	   0, 2, 2, 1, 1, 3, 4, 5, 6
>+};
>+static const char unary_operations[]  = "(+-"; static const char
>+binary_operations[] = " +-*/&^|)";
>+
>+static uint32_t do_func(uint32_t val1, uint32_t val2, int op) {
>+	switch (op) {
>+	case 1:
>+		return val1 + val2;
>+	case 2:
>+		return val1 - val2;
>+	case 3:
>+		return val1 * val2;
>+	case 4:
>+		return val1 / val2;
>+	case 5:
>+		return val1 & val2;
>+	case 6:
>+		return val1 ^ val2;
>+	case 7:
>+		return val1 | val2;
>+	}
>+	fprintf(stderr, "Error: in func %s: val1=%d val2=%d op = %d\n",
>+			__func__, val1, val2, op);
>+	exit(EXIT_FAILURE);
>+}
>+
>+static int find_op(char c, const char *p) {
>+	int i;
>+	for (i = 0; ; i++) {
>+		if (c == p[i])
>+			return i;
>+		if (!p[i])
>+			break;
>+	}
>+	return -1;
>+}
>+
>+#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
>+
> int ph_get_value(struct parse_helper *ph, uint32_t *pval)  {
> 	char *endptr;
>-	uint32_t value;
>+	int op_i = 0;
>+	int val_i = 0;
>+	unsigned char op[16];
>+	uint32_t val[16];
>+	int unary = 1;
>+	char *p;
>
>-	if (ph_skip_separators(ph))
>-		return -1;
>-	errno = 0;
>-	value = strtoul(ph->p, &endptr, 16);
>-	if (errno || (ph->p == endptr))
>-		return -1;
>-	*pval = value;
>-	ph->p = endptr;
>-	return 0;
>+	p = ph->p;
>+	for (;;) {
>+		char c;
>+		int i, j;
>+		const char *ops = unary ? unary_operations :
>binary_operations;
>+
>+		if (unary) {
>+			ph->p = p;
>+			if (ph_skip_separators(ph))
>+				return -1;
>+			p = ph->p;
>+			c = *p;
>+		} else {
>+			for (;;) {
>+				c = *p;
>+				if ((c != ' ') && (c != '\t'))
>+					break;
>+				p++;
>+			}
>+		}
>+		i = find_op(c, ops);
>+		debug("%d,%c,%d:%s\n", i, c, unary, p);
>+		if ((i < 0) && unary) {
>+			if (val_i >= ARRAY_SIZE(val))
>+				return -1;
>+			errno = 0;
>+			val[val_i++] = strtoul(p, &endptr, 16);
>+			if (errno || (p == endptr)) {
>+				ph->p = p;
>+				return -1;
>+			}
>+			p = endptr;
>+			unary = 0;
>+			debug("val[%d]=%x,%d,%d\n", val_i - 1, val[val_i - 1],
>+					op_i, val_i);
>+do_unary:
>+			while (op_i) {
>+				j = op[op_i - 1];
>+				if (!(j & 0x80))
>+					break;
>+				op_i--;
>+				val[val_i - 1] = do_func(0,
>+						val[val_i - 1], j & 0x7f);
>+				debug("un:%d,%x,%d,%d\n", val[val_i - 1], j,
>+						op_i, val_i);
>+			}
>+			continue;
>+		}
>+		if (i < 0) {
>+			c = 0;
>+			i = 8;
>+		} else {
>+			p++;
>+		}
>+		if (c == '(') {
>+			if (op_i >= ARRAY_SIZE(op))
>+				return -1;
>+			op[op_i++] = i;
>+			debug("op[%d]=%x,%d,%d\n", op_i - 1, op[op_i - 1],
>+					op_i, val_i);
>+			unary = 1;
>+			continue;
>+		}
>+		for (;;) {
>+			if (!op_i || unary)
>+				break;
>+			j = op[op_i - 1];
>+			if (j == 0) {
>+				if (c == ')') {
>+					op_i--;
>+					goto do_unary;
>+				}
>+				break;
>+			}
>+			if ((j & 0x80)) {
>+				op_i--;
>+				val[val_i - 1] = do_func(0,
>+						val[val_i - 1], j & 0x7f);
>+				debug("unary:%d,%x\n", val[val_i - 1], j);
>+				continue;
>+			}
>+			if (precedence[i] < precedence[j])
>+				break;
>+			if (val_i < 2)
>+				return -1;
>+			op_i--;
>+			val[val_i - 2] = do_func(val[val_i - 2],
>+					val[val_i - 1], j);
>+			val_i--;
>+			debug("binary:%d,%x,%d,%d\n", val[val_i - 1], j,
>+					op_i, val_i);
>+		}
>+		if (c == ')') {
>+			fprintf(stderr, "Error: unmatched parenthesis\n");
>+			return -1;
>+		}
>+		if (i == 8) {
>+			if ((op_i != 0) || (val_i != 1)) {
>+				fprintf(stderr, "Error: syntax %d %d\n",
>+						op_i, val_i);
>+				return -1;
>+			}
>+			ph->p = p;
>+			*pval = val[0];
>+			return 0;
>+		}
>+		if (op_i >= ARRAY_SIZE(op))
>+			return -1;
>+		op[op_i++] = i | (unary << 7);
>+		debug("op[%d]=%x,%d,%d\n", op_i - 1, op[op_i - 1], op_i, val_i);
>+		unary = 1;
>+	}
> }
>
> /*
>--
>1.7.9.5
>