factor unpack core into read_fields

1 files changed, 77 insertions, 69 deletions

diff --git a/unpack.c b/unpack.c
index 3143931..836faf3 100644
--- a/unpack.c
+++ b/unpack.c
@@ -15,6 +15,18 @@
 #include "pack.h"
 #include "trace.h"
 
+struct dest {
+	enum pack_type type;
+	union ptr {
+		#define T(type, sign, c_type, va_type) sign c_type *type;
+		ITYPE_MACROS
+		#undef T
+		float *f;
+		double *d;
+	} ptr;
+	size_t count;
+};
+
 static uintmax_t read_val(const unsigned char *buf, size_t size, enum pack_endian e)
 {
 	uintmax_t val = 0;
@@ -36,6 +48,57 @@ static intmax_t minval(size_t s)
 	}
 }
 
+static void read_fields(struct dest dest, const void *src_, enum pack_endian endianness)
+{
+	union {
+		uintmax_t unsigned_;
+		intmax_t signed_;
+		float f;
+		double d;
+	} val;
+	const unsigned char *src = src_;
+	size_t s = getsize(dest.type);
+
+	for (size_t i = 0; i < dest.count; i++) {
+		val.unsigned_ =
+			read_val(&src[s * i], s, endianness);
+		tr_debug("val.u: %" PRIuMAX ", at: %" PRIuSIZE,
+			 val.unsigned_, s * i);
+
+		if (dest.type == PACK_TYPE_FLOAT) {
+			float f = ieee754b32_deserialise(val.unsigned_);
+			val.f = f;
+			tr_debug("val.f: %f", val.f);
+		} else if (dest.type == PACK_TYPE_DOUBLE) {
+			double d = ieee754b64_deserialise(val.unsigned_);
+			val.d = d;
+			tr_debug("val.d: %f", val.d);
+		} else if (islower((char)dest.type)) {
+			intmax_t vals;
+			if (!(val.unsigned_ & (UINTMAX_C(1) << (s * 8 - 1)))) {
+				vals = val.unsigned_;
+			} else {
+				vals = minval(s);
+				vals += val.unsigned_ ^ (UINTMAX_C(1) << (s * 8 - 1));
+			}
+			val.signed_ = vals;
+			tr_debug("val.s: %" PRIdMAX, val.signed_);
+		}
+
+		switch (dest.type) {
+		#define T(type, sign, c_type, va_type) \
+			case (char)PACK_TYPE_##type: \
+				dest.ptr.type[i] = val.sign##_; \
+				break;
+		ITYPE_MACROS
+		#undef T
+		case PACK_TYPE_FLOAT: dest.ptr.f[i] = val.f; break;
+		case PACK_TYPE_DOUBLE: dest.ptr.d[i] = val.d; break;
+		case PACK_TYPE_PADDING: break;
+		}
+	}
+}
+
 enum pack_status unpack(const void *buf_, size_t size, const char *fmt, ...)
 {
 	enum pack_endian endianness = PACK_ENDIAN_BIG;
@@ -49,23 +112,8 @@ enum pack_status unpack(const void *buf_, size_t size, const char *fmt, ...)
 	va_start(ap, fmt);
 
 	for (int i = 0; fmt[i] != '\0'; i++) {
-		bool sign;
-		size_t count = 1, s;
-		enum pack_type t;
-		union {
-			#define T(type, sign, c_type, va_type) \
-				sign c_type *type;
-			ITYPE_MACROS
-			#undef T
-			float     *f;
-			double    *d;
-		} arg;
-		union {
-			uintmax_t unsigned_;
-			intmax_t signed_;
-			float f;
-			double d;
-		} val;
+		size_t s;
+		struct dest dest = { .count = 1 };
 		tr_debug("i: %d, fmt[i]: %c", i, fmt[i]);
 		if (isdigit(fmt[i])) {
 			unsigned long long c;
@@ -75,80 +123,40 @@ enum pack_status unpack(const void *buf_, size_t size, const char *fmt, ...)
 			c = strtoull(&fmt[i], &end, 10);
 			if ((c == ULLONG_MAX && errno == ERANGE) || c > SIZE_MAX)
 				SET_AND_GOTO(ret, PACK_FMTINVAL, stop);
-			count = c;
+			dest.count = c;
 			i += end - &fmt[i];
 		} else if (fmt[i] == '*') {
-			count = va_arg(ap, size_t);
+			dest.count = va_arg(ap, size_t);
 			i++;
 		}
-		sign = islower(fmt[i]);
-		tr_debug("count: %" PRIuSIZE ", i: %d, fmt[i]: %c, sign: %ssigned",
-			 count, i, fmt[i], sign ? "" : "un");
+		tr_debug("dest.count: %" PRIuSIZE ", i: %d, fmt[i]: %c", dest.count, i, fmt[i]);
 		switch (fmt[i]) {
 		case '>': endianness = PACK_ENDIAN_BIG; continue;
 		case '<': endianness = PACK_ENDIAN_LITTLE; continue;
 		#define T(type, sign, c_type, va_type) \
 			case (char)PACK_TYPE_##type: \
-				arg.type = va_arg(ap, sign c_type *); \
+				dest.ptr.type = va_arg(ap, sign c_type *); \
 				break;
 		ITYPE_MACROS
 		#undef T
-		case PACK_TYPE_FLOAT: arg.f = va_arg(ap, float *); break;
-		case PACK_TYPE_DOUBLE: arg.d = va_arg(ap, double *); break;
+		case PACK_TYPE_FLOAT: dest.ptr.f = va_arg(ap, float *); break;
+		case PACK_TYPE_DOUBLE: dest.ptr.d = va_arg(ap, double *); break;
 		case PACK_TYPE_PADDING: break;
 		default: SET_AND_GOTO(ret, PACK_FMTINVAL, stop);
 		}
-		t = fmt[i];
+		dest.type = fmt[i];
 
-		s = getsize(t);
+		s = getsize(dest.type);
 		tr_debug("s: %" PRIuSIZE, s);
 		if (s == (size_t)-1) SET_AND_GOTO(ret, PACK_FMTINVAL, stop);
 
-		if (size - offset < s * count)
+		if (size - offset < s * dest.count)
 			SET_AND_GOTO(ret, PACK_TOOSMALL, stop);
 
-		if (t == PACK_TYPE_PADDING) goto skip;
-
-		for (size_t j = 0; j < count; j++) {
-			val.unsigned_ =
-				read_val(buf + offset + s * j, s, endianness);
-			tr_debug("val.u: %" PRIuMAX ", at: %" PRIuSIZE,
-			         val.unsigned_, offset + s * j);
-
-			if (t == PACK_TYPE_FLOAT) {
-				float f = ieee754b32_deserialise(val.unsigned_);
-				val.f = f;
-				tr_debug("val.f: %f", val.f);
-			} else if (t == PACK_TYPE_DOUBLE) {
-				double d = ieee754b64_deserialise(val.unsigned_);
-				val.d = d;
-				tr_debug("val.d: %f", val.d);
-			} else if (sign) {
-				intmax_t vals;
-				if (!(val.unsigned_ & (UINTMAX_C(1) << (s * 8 - 1)))) {
-					vals = val.unsigned_;
-				} else {
-					vals = minval(s);
-					vals += val.unsigned_ ^ (UINTMAX_C(1) << (s * 8 - 1));
-				}
-				val.signed_ = vals;
-				tr_debug("val.s: %" PRIdMAX, val.signed_);
-			}
+		if (dest.type != PACK_TYPE_PADDING)
+			read_fields(dest, &buf[offset], endianness);
 
-			switch (t) {
-			#define T(type, sign, c_type, va_type) \
-				case (char)PACK_TYPE_##type: \
-					arg.type[j] = val.sign##_; \
-					break;
-			ITYPE_MACROS
-			#undef T
-			case PACK_TYPE_FLOAT: arg.f[j] = val.f; break;
-			case PACK_TYPE_DOUBLE: arg.d[j] = val.d; break;
-			case PACK_TYPE_PADDING: break;
-			}
-		}
-skip:
-		offset += s * count;
+		offset += s * dest.count;
 	}
 
 stop: