UZ80 is a freeware Z80 assembler that aims to be both small and fast while still providing valuable services such as macro instructions and conditional assembly. Internally, it departs from full two-pass methods and relies instead on assembling as much code as possible during the first pass and writing down the lines making references to still unseen symbols; these lines will be assembled when all symbols are known.
How to use
UZ80 relies on the standard C library, it doesn't need other libraries to run. Its command line syntax is as follows:
-q : quiet mode, no messages other than fatal errors are shown;
-v : verbose mode, all messages are shown; -vv shows even more information, such as label and macro dumps;
-Dlabel=value : defines a symbol named "label" whose value is "value";
-Dlabel : shortcut for "-Dlabel=1";
-D : shortcut for "-DDEBUG=1";
source : the source file; must be followed by a target file;
target : the target file; must follow a source file.
The assembly syntax itself is as follows:
[label] [instruction [parameter[,parameter ...]]
Indenting is important: labels must begin on the first character of each line and instructions start later in the line even when there are no labels. Instructions are either those belonging to the Z80, or the following pseudo instructions:
org EXPRESSION : sets the assembly origin point at EXPRESSION;
align EXPRESSION : aligns the current assembly point to the next address that is a multiplo of EXPRESSION;
defb EXPRESSION... : defines a data block as a series of bytes separated with commas; strings within quotes can be used, too;
defw EXPRESSION... : like "defb", but with 16-bit words and without strings;
defd EXPRESSION... : like "defw", but with 32-bit double words;
defs EXPRESSION : fills with zeroes the amount of bytes set by EXPRESSION;
LABEL equ EXPRESSION / LABEL = EXPRESSION : creates a new symbol named LABEL whose value will be EXPRESSION;
if EXPRESSION : assembles the next lines if EXPRESSION is nonzero (conditional assembly); "else" can follow, "endif" must follow;
else : assembles the next lines if the current conditional assembly is false; must follow "if", "endif" must follow;
endif : ends the current conditional assembly; can follow "else", must follow "if";
include "FILENAME" : includes the contents of another source file named FILENAME within the current assembly;
LABEL macro [PARAM1[,PARAM2 ...] : defines a macro instruction named LABEL featuring the optional parameters PARAM1, PARAM2...
endm : ends the definition of the current macro;
end : stops assembling the current source file.
Expressions are similar to those used in C and in other assemblers: integers (either decimal, hexadecimal formatted as $1234, #1234, 1234h or 0x1234, or binary formatted as %01010101 or 01010101b) and symbol values (case-insensitive; "$" stands for the current address) can endure addition ('+'), substraction ('-'), multiplication ('*'), division ('/'), modulo ('%'), logical NOT ('!'), bitwise NOT ('~'), bitwise AND ('&'), bitwise OR ('|'), bitwise XOR ('^'), left shift ('<<'), right shift ('>>') and several types of comparison ('<', '<=', '='/'==', '<>'/'!=', '>=', '>'); by default, these operations follow basic precedence rules such as additions and substractions happening after multiplications and divisions, but before comparisons, unless parentheses are used to prioritise some operations over others. Notice that "equ" and "macro" must include labels and thus need to begin on the first character of the line. An example of a macro with parameters is as follows:
Using it with "memcpy buffer,string,10" generates the following code:
Originally undocumented instructions such as SLL (Shift Left Logical) and OUT (C),0 and parameters such as the high and low halves of IX and IY (XH, XL, YH and YL respectively) are supported, as well as synonyms:
DEFM : DEFB
DB : DEFB
DW : DEFW
DD : DEFD
DS : DEFS
IXH / HX : XH
IXL / LX : XL
IYH / HY : YH
IYL / LY : YL
OTD : OUTD
OTI : OUTI
SHL : SLA
SHR : SRL
PUSH REG1,REG2[,...] : PUSH REG1 + PUSH REG2 [+ ...]
POP REG1,REG2[,...] : [... +] POP REG2 + POP REG1
NOP NUMBER : NOP repeated NUMBER times
The pseudoinstructions "if" and "include" can be recursively nested; however, too much nesting will cause a fatal error. Exit codes are either 0 (success) or 1 (fatal error); errors will show a short message stating the type of error and its location in the source.
20180321-2040: first public release. Succesfully compiles FROGALOT, HIREHARE, BASKETCS and the CHIPNSFX player demo.
20180322-1930: second public release. Added instructions OUTD and OUTI (synonyms of OTD and OTI) and fixed inconsistencies when using a macro with fewer parameters than defined.