Implement STRFMT and more printf-like format specifiers for string interpolation (#646)

Fixes #570
Fixes #178

Use errors for inapplicable format spec flags instead of -Wstring-format

test/asm/bracketed-symbols.err

@@ -1,5 +1,5 @@
 ERROR: bracketed-symbols.asm(16):
-    Print types are only allowed for numbers
+    Formatting string as type 'X'
 ERROR: bracketed-symbols.asm(20):
     "Label" does not have a constant value
 ERROR: bracketed-symbols.asm(21):

test/asm/strfmt.asm

@@ -0,0 +1,24 @@
+VAL EQUS STRFMT("Hello %s! I am %d years old today!", "world", $f)
+PRINTT "{VAL}\n"
+
+N = -42
+PRINTT STRFMT("signed %010d == unsigned %010u\n", N, N)
+
+N = 112
+FMT EQUS "X"
+PRINTT STRFMT("\tdb %#03{s:FMT} %% 26\t; %#03{FMT}\n", N, N % 26)
+
+TEMPLATE EQUS "\"%s are %s\\n\""
+PRINTT STRFMT(TEMPLATE, "roses", "red")
+PRINTT STRFMT(TEMPLATE, "violets", "blue")
+PRINTT STRFMT(TEMPLATE, "void", 0, "extra")
+
+PRINTT STRCAT(STRFMT(STRFMT("%%%s.%d%s", "", 9, "f"), _PI), \
+	STRFMT(" ~ %s\n", STRFMT("%s%x", "thr", 238)))
+
+PRINTT STRFMT("%d eol %", 1)
+PRINTT "\n"
+
+PRINTT STRFMT("invalid %w spec\n", 42)
+
+PRINTT STRFMT("one=%d two=%d three=%d\n", 1)

test/asm/strfmt.err

@@ -0,0 +1,11 @@
+ERROR: strfmt.asm(14):
+    Formatting number as type 's'
+ERROR: strfmt.asm(14):
+    STRFMT: 1 unformatted argument(s)
+ERROR: strfmt.asm(19):
+    STRFMT: Illegal '%' at end of format string
+ERROR: strfmt.asm(22):
+    STRFMT: Invalid format spec for argument 1
+ERROR: strfmt.asm(24):
+    STRFMT: Not enough arguments for format spec
+error: Assembly aborted (5 errors)!

test/asm/strfmt.out

@@ -0,0 +1,10 @@
+Hello world! I am 15 years old today!
+signed -000000042 == unsigned 4294967254
+	db $70 % 26	; $08
+roses are red
+violets are blue
+void are 0
+3.141586304 ~ three
+1 eol %
+invalid % spec
+one=1 two=% three=%

test/asm/string-formatting.asm

@@ -0,0 +1,15 @@
+n equ 300
+m equ -42
+f equ -123.0456
+s equs "hello"
+
+	printt "<{ -6d:n}> <{+06u:n}> <{5x:n}> <{#16b:n}>\n"
+	printt "<{u:m}> <{+3d:m}> <{#016o:m}>\n"
+	printt "<{f:_PI}> <{06f:f}> <{.10f:f}>\n"
+	printt "<{#-10s:s}> <{10s:s}>\n"
+
+foo: macro
+	printt "<{\1}>\n"
+endm
+
+	foo  -6d:n ; space is trimmed

test/asm/string-formatting.err

@@ -0,0 +1,3 @@
+ERROR: string-formatting.asm(9):
+    Formatting string with prefix flag '#'
+error: Assembly aborted (1 errors)!

test/asm/string-formatting.out

@@ -0,0 +1,5 @@
+< 300  > <+00300> <  12c> <      %100101100>
+<4294967254> <-42> <&000037777777726>
+<3.14159> <-00123> <-123.0455932618>
+<hello     > <     hello>
+<300   >