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| <h4 class="subsection">3.17.4 AVR Options</h4> |
| |
| <p><a name="index-AVR-Options-1151"></a> |
| These options are defined for AVR implementations: |
| |
| <dl> |
| <dt><code>-mmcu=</code><var>mcu</var><dd><a name="index-mmcu-1152"></a>Specify Atmel AVR instruction set architectures (ISA) or MCU type. |
| |
| <p>The default for this option is <code>avr2</code>. |
| |
| <p>GCC supports the following AVR devices and ISAs: |
| |
| <!-- Copyright (C) 2012-2013 Free Software Foundation, Inc. --> |
| <!-- This is part of the GCC manual. --> |
| <!-- For copying conditions, see the file gcc/doc/include/fdl.texi. --> |
| <!-- This file is generated automatically using --> |
| <!-- gcc/config/avr/gen-avr-mmcu-texi.c from: --> |
| <!-- gcc/config/avr/avr-arch.h --> |
| <!-- gcc/config/avr/avr-devices.c --> |
| <!-- gcc/config/avr/avr-mcus.def --> |
| <!-- Please do not edit manually. --> |
| <dl> |
| <dt><code>avr2</code><dd>“Classic” devices with up to 8 KiB of program memory. |
| <br><var>mcu</var> = <code>attiny22</code>, <code>attiny26</code>, <code>at90c8534</code>, <code>at90s2313</code>, <code>at90s2323</code>, <code>at90s2333</code>, <code>at90s2343</code>, <code>at90s4414</code>, <code>at90s4433</code>, <code>at90s4434</code>, <code>at90s8515</code>, <code>at90s8535</code>. |
| |
| <br><dt><code>avr25</code><dd>“Classic” devices with up to 8 KiB of program memory and with the <code>MOVW</code> instruction. |
| <br><var>mcu</var> = <code>ata5272</code>, <code>ata6289</code>, <code>attiny13</code>, <code>attiny13a</code>, <code>attiny2313</code>, <code>attiny2313a</code>, <code>attiny24</code>, <code>attiny24a</code>, <code>attiny25</code>, <code>attiny261</code>, <code>attiny261a</code>, <code>attiny43u</code>, <code>attiny4313</code>, <code>attiny44</code>, <code>attiny44a</code>, <code>attiny45</code>, <code>attiny461</code>, <code>attiny461a</code>, <code>attiny48</code>, <code>attiny84</code>, <code>attiny84a</code>, <code>attiny85</code>, <code>attiny861</code>, <code>attiny861a</code>, <code>attiny87</code>, <code>attiny88</code>, <code>at86rf401</code>. |
| |
| <br><dt><code>avr3</code><dd>“Classic” devices with 16 KiB up to 64 KiB of program memory. |
| <br><var>mcu</var> = <code>at43usb355</code>, <code>at76c711</code>. |
| |
| <br><dt><code>avr31</code><dd>“Classic” devices with 128 KiB of program memory. |
| <br><var>mcu</var> = <code>atmega103</code>, <code>at43usb320</code>. |
| |
| <br><dt><code>avr35</code><dd>“Classic” devices with 16 KiB up to 64 KiB of program memory and with the <code>MOVW</code> instruction. |
| <br><var>mcu</var> = <code>ata5505</code>, <code>atmega16u2</code>, <code>atmega32u2</code>, <code>atmega8u2</code>, <code>attiny1634</code>, <code>attiny167</code>, <code>at90usb162</code>, <code>at90usb82</code>. |
| |
| <br><dt><code>avr4</code><dd>“Enhanced” devices with up to 8 KiB of program memory. |
| <br><var>mcu</var> = <code>ata6285</code>, <code>ata6286</code>, <code>atmega48</code>, <code>atmega48a</code>, <code>atmega48p</code>, <code>atmega48pa</code>, <code>atmega8</code>, <code>atmega8a</code>, <code>atmega8hva</code>, <code>atmega8515</code>, <code>atmega8535</code>, <code>atmega88</code>, <code>atmega88a</code>, <code>atmega88p</code>, <code>atmega88pa</code>, <code>at90pwm1</code>, <code>at90pwm2</code>, <code>at90pwm2b</code>, <code>at90pwm3</code>, <code>at90pwm3b</code>, <code>at90pwm81</code>. |
| |
| <br><dt><code>avr5</code><dd>“Enhanced” devices with 16 KiB up to 64 KiB of program memory. |
| <br><var>mcu</var> = <code>ata5790</code>, <code>ata5790n</code>, <code>ata5795</code>, <code>atmega16</code>, <code>atmega16a</code>, <code>atmega16hva</code>, <code>atmega16hva2</code>, <code>atmega16hvb</code>, <code>atmega16hvbrevb</code>, <code>atmega16m1</code>, <code>atmega16u4</code>, <code>atmega161</code>, <code>atmega162</code>, <code>atmega163</code>, <code>atmega164a</code>, <code>atmega164p</code>, <code>atmega164pa</code>, <code>atmega165</code>, <code>atmega165a</code>, <code>atmega165p</code>, <code>atmega165pa</code>, <code>atmega168</code>, <code>atmega168a</code>, <code>atmega168p</code>, <code>atmega168pa</code>, <code>atmega169</code>, <code>atmega169a</code>, <code>atmega169p</code>, <code>atmega169pa</code>, <code>atmega26hvg</code>, <code>atmega32</code>, <code>atmega32a</code>, <code>atmega32c1</code>, <code>atmega32hvb</code>, <code>atmega32hvbrevb</code>, <code>atmega32m1</code>, <code>atmega32u4</code>, <code>atmega32u6</code>, <code>atmega323</code>, <code>atmega324a</code>, <code>atmega324p</code>, <code>atmega324pa</code>, <code>atmega325</code>, <code>atmega325a</code>, <code>atmega325p</code>, <code>atmega3250</code>, <code>atmega3250a</code>, <code>atmega3250p</code>, <code>atmega3250pa</code>, <code>atmega328</code>, <code>atmega328p</code>, <code>atmega329</code>, <code>atmega329a</code>, <code>atmega329p</code>, <code>atmega329pa</code>, <code>atmega3290</code>, <code>atmega3290a</code>, <code>atmega3290p</code>, <code>atmega3290pa</code>, <code>atmega406</code>, <code>atmega48hvf</code>, <code>atmega64</code>, <code>atmega64a</code>, <code>atmega64c1</code>, <code>atmega64hve</code>, <code>atmega64m1</code>, <code>atmega64rfa2</code>, <code>atmega64rfr2</code>, <code>atmega640</code>, <code>atmega644</code>, <code>atmega644a</code>, <code>atmega644p</code>, <code>atmega644pa</code>, <code>atmega645</code>, <code>atmega645a</code>, <code>atmega645p</code>, <code>atmega6450</code>, <code>atmega6450a</code>, <code>atmega6450p</code>, <code>atmega649</code>, <code>atmega649a</code>, <code>atmega649p</code>, <code>atmega6490</code>, <code>atmega6490a</code>, <code>atmega6490p</code>, <code>at90can32</code>, <code>at90can64</code>, <code>at90pwm161</code>, <code>at90pwm216</code>, <code>at90pwm316</code>, <code>at90scr100</code>, <code>at90usb646</code>, <code>at90usb647</code>, <code>at94k</code>, <code>m3000</code>. |
| |
| <br><dt><code>avr51</code><dd>“Enhanced” devices with 128 KiB of program memory. |
| <br><var>mcu</var> = <code>atmega128</code>, <code>atmega128a</code>, <code>atmega128rfa1</code>, <code>atmega1280</code>, <code>atmega1281</code>, <code>atmega1284</code>, <code>atmega1284p</code>, <code>at90can128</code>, <code>at90usb1286</code>, <code>at90usb1287</code>. |
| |
| <br><dt><code>avr6</code><dd>“Enhanced” devices with 3-byte PC, i.e. with more than 128 KiB of program memory. |
| <br><var>mcu</var> = <code>atmega2560</code>, <code>atmega2561</code>. |
| |
| <br><dt><code>avrxmega2</code><dd>“XMEGA” devices with more than 8 KiB and up to 64 KiB of program memory. |
| <br><var>mcu</var> = <code>atmxt112sl</code>, <code>atmxt224</code>, <code>atmxt224e</code>, <code>atmxt336s</code>, <code>atxmega16a4</code>, <code>atxmega16a4u</code>, <code>atxmega16c4</code>, <code>atxmega16d4</code>, <code>atxmega16x1</code>, <code>atxmega32a4</code>, <code>atxmega32a4u</code>, <code>atxmega32c4</code>, <code>atxmega32d4</code>, <code>atxmega32e5</code>, <code>atxmega32x1</code>. |
| |
| <br><dt><code>avrxmega4</code><dd>“XMEGA” devices with more than 64 KiB and up to 128 KiB of program memory. |
| <br><var>mcu</var> = <code>atxmega64a3</code>, <code>atxmega64a3u</code>, <code>atxmega64a4u</code>, <code>atxmega64b1</code>, <code>atxmega64b3</code>, <code>atxmega64c3</code>, <code>atxmega64d3</code>, <code>atxmega64d4</code>. |
| |
| <br><dt><code>avrxmega5</code><dd>“XMEGA” devices with more than 64 KiB and up to 128 KiB of program memory and more than 64 KiB of RAM. |
| <br><var>mcu</var> = <code>atxmega64a1</code>, <code>atxmega64a1u</code>. |
| |
| <br><dt><code>avrxmega6</code><dd>“XMEGA” devices with more than 128 KiB of program memory. |
| <br><var>mcu</var> = <code>atmxt540s</code>, <code>atmxt540sreva</code>, <code>atxmega128a3</code>, <code>atxmega128a3u</code>, <code>atxmega128b1</code>, <code>atxmega128b3</code>, <code>atxmega128c3</code>, <code>atxmega128d3</code>, <code>atxmega128d4</code>, <code>atxmega192a3</code>, <code>atxmega192a3u</code>, <code>atxmega192c3</code>, <code>atxmega192d3</code>, <code>atxmega256a3</code>, <code>atxmega256a3b</code>, <code>atxmega256a3bu</code>, <code>atxmega256a3u</code>, <code>atxmega256c3</code>, <code>atxmega256d3</code>, <code>atxmega384c3</code>, <code>atxmega384d3</code>. |
| |
| <br><dt><code>avrxmega7</code><dd>“XMEGA” devices with more than 128 KiB of program memory and more than 64 KiB of RAM. |
| <br><var>mcu</var> = <code>atxmega128a1</code>, <code>atxmega128a1u</code>, <code>atxmega128a4u</code>. |
| |
| <br><dt><code>avr1</code><dd>This ISA is implemented by the minimal AVR core and supported for assembler only. |
| <br><var>mcu</var> = <code>attiny11</code>, <code>attiny12</code>, <code>attiny15</code>, <code>attiny28</code>, <code>at90s1200</code>. |
| |
| </dl> |
| |
| <br><dt><code>-maccumulate-args</code><dd><a name="index-maccumulate_002dargs-1153"></a>Accumulate outgoing function arguments and acquire/release the needed |
| stack space for outgoing function arguments once in function |
| prologue/epilogue. Without this option, outgoing arguments are pushed |
| before calling a function and popped afterwards. |
| |
| <p>Popping the arguments after the function call can be expensive on |
| AVR so that accumulating the stack space might lead to smaller |
| executables because arguments need not to be removed from the |
| stack after such a function call. |
| |
| <p>This option can lead to reduced code size for functions that perform |
| several calls to functions that get their arguments on the stack like |
| calls to printf-like functions. |
| |
| <br><dt><code>-mbranch-cost=</code><var>cost</var><dd><a name="index-mbranch_002dcost-1154"></a>Set the branch costs for conditional branch instructions to |
| <var>cost</var>. Reasonable values for <var>cost</var> are small, non-negative |
| integers. The default branch cost is 0. |
| |
| <br><dt><code>-mcall-prologues</code><dd><a name="index-mcall_002dprologues-1155"></a>Functions prologues/epilogues are expanded as calls to appropriate |
| subroutines. Code size is smaller. |
| |
| <br><dt><code>-mint8</code><dd><a name="index-mint8-1156"></a>Assume <code>int</code> to be 8-bit integer. This affects the sizes of all types: a |
| <code>char</code> is 1 byte, an <code>int</code> is 1 byte, a <code>long</code> is 2 bytes, |
| and <code>long long</code> is 4 bytes. Please note that this option does not |
| conform to the C standards, but it results in smaller code |
| size. |
| |
| <br><dt><code>-mno-interrupts</code><dd><a name="index-mno_002dinterrupts-1157"></a>Generated code is not compatible with hardware interrupts. |
| Code size is smaller. |
| |
| <br><dt><code>-mrelax</code><dd><a name="index-mrelax-1158"></a>Try to replace <code>CALL</code> resp. <code>JMP</code> instruction by the shorter |
| <code>RCALL</code> resp. <code>RJMP</code> instruction if applicable. |
| Setting <code>-mrelax</code> just adds the <code>--relax</code> option to the |
| linker command line when the linker is called. |
| |
| <p>Jump relaxing is performed by the linker because jump offsets are not |
| known before code is located. Therefore, the assembler code generated by the |
| compiler is the same, but the instructions in the executable may |
| differ from instructions in the assembler code. |
| |
| <p>Relaxing must be turned on if linker stubs are needed, see the |
| section on <code>EIND</code> and linker stubs below. |
| |
| <br><dt><code>-msp8</code><dd><a name="index-msp8-1159"></a>Treat the stack pointer register as an 8-bit register, |
| i.e. assume the high byte of the stack pointer is zero. |
| In general, you don't need to set this option by hand. |
| |
| <p>This option is used internally by the compiler to select and |
| build multilibs for architectures <code>avr2</code> and <code>avr25</code>. |
| These architectures mix devices with and without <code>SPH</code>. |
| For any setting other than <code>-mmcu=avr2</code> or <code>-mmcu=avr25</code> |
| the compiler driver will add or remove this option from the compiler |
| proper's command line, because the compiler then knows if the device |
| or architecture has an 8-bit stack pointer and thus no <code>SPH</code> |
| register or not. |
| |
| <br><dt><code>-mstrict-X</code><dd><a name="index-mstrict_002dX-1160"></a>Use address register <code>X</code> in a way proposed by the hardware. This means |
| that <code>X</code> is only used in indirect, post-increment or |
| pre-decrement addressing. |
| |
| <p>Without this option, the <code>X</code> register may be used in the same way |
| as <code>Y</code> or <code>Z</code> which then is emulated by additional |
| instructions. |
| For example, loading a value with <code>X+const</code> addressing with a |
| small non-negative <code>const < 64</code> to a register <var>Rn</var> is |
| performed as |
| |
| <pre class="example"> adiw r26, const ; X += const |
| ld <var>Rn</var>, X ; <var>Rn</var> = *X |
| sbiw r26, const ; X -= const |
| </pre> |
| <br><dt><code>-mtiny-stack</code><dd><a name="index-mtiny_002dstack-1161"></a>Only change the lower 8 bits of the stack pointer. |
| |
| <br><dt><code>-Waddr-space-convert</code><dd><a name="index-Waddr_002dspace_002dconvert-1162"></a>Warn about conversions between address spaces in the case where the |
| resulting address space is not contained in the incoming address space. |
| </dl> |
| |
| <h5 class="subsubsection">3.17.4.1 <code>EIND</code> and Devices with more than 128 Ki Bytes of Flash</h5> |
| |
| <p><a name="index-g_t_0040code_007bEIND_007d-1163"></a>Pointers in the implementation are 16 bits wide. |
| The address of a function or label is represented as word address so |
| that indirect jumps and calls can target any code address in the |
| range of 64 Ki words. |
| |
| <p>In order to facilitate indirect jump on devices with more than 128 Ki |
| bytes of program memory space, there is a special function register called |
| <code>EIND</code> that serves as most significant part of the target address |
| when <code>EICALL</code> or <code>EIJMP</code> instructions are used. |
| |
| <p>Indirect jumps and calls on these devices are handled as follows by |
| the compiler and are subject to some limitations: |
| |
| <ul> |
| <li>The compiler never sets <code>EIND</code>. |
| |
| <li>The compiler uses <code>EIND</code> implicitely in <code>EICALL</code>/<code>EIJMP</code> |
| instructions or might read <code>EIND</code> directly in order to emulate an |
| indirect call/jump by means of a <code>RET</code> instruction. |
| |
| <li>The compiler assumes that <code>EIND</code> never changes during the startup |
| code or during the application. In particular, <code>EIND</code> is not |
| saved/restored in function or interrupt service routine |
| prologue/epilogue. |
| |
| <li>For indirect calls to functions and computed goto, the linker |
| generates <em>stubs</em>. Stubs are jump pads sometimes also called |
| <em>trampolines</em>. Thus, the indirect call/jump jumps to such a stub. |
| The stub contains a direct jump to the desired address. |
| |
| <li>Linker relaxation must be turned on so that the linker will generate |
| the stubs correctly an all situaltion. See the compiler option |
| <code>-mrelax</code> and the linler option <code>--relax</code>. |
| There are corner cases where the linker is supposed to generate stubs |
| but aborts without relaxation and without a helpful error message. |
| |
| <li>The default linker script is arranged for code with <code>EIND = 0</code>. |
| If code is supposed to work for a setup with <code>EIND != 0</code>, a custom |
| linker script has to be used in order to place the sections whose |
| name start with <code>.trampolines</code> into the segment where <code>EIND</code> |
| points to. |
| |
| <li>The startup code from libgcc never sets <code>EIND</code>. |
| Notice that startup code is a blend of code from libgcc and AVR-LibC. |
| For the impact of AVR-LibC on <code>EIND</code>, see the |
| <a href="http://nongnu.org/avr-libc/user-manual/">AVR-LibC user manual</a><!-- /@w -->. |
| |
| <li>It is legitimate for user-specific startup code to set up <code>EIND</code> |
| early, for example by means of initialization code located in |
| section <code>.init3</code>. Such code runs prior to general startup code |
| that initializes RAM and calls constructors, but after the bit |
| of startup code from AVR-LibC that sets <code>EIND</code> to the segment |
| where the vector table is located. |
| <pre class="example"> #include <avr/io.h> |
| |
| static void |
| __attribute__((section(".init3"),naked,used,no_instrument_function)) |
| init3_set_eind (void) |
| { |
| __asm volatile ("ldi r24,pm_hh8(__trampolines_start)\n\t" |
| "out %i0,r24" :: "n" (&EIND) : "r24","memory"); |
| } |
| </pre> |
| <p class="noindent">The <code>__trampolines_start</code> symbol is defined in the linker script. |
| |
| <li>Stubs are generated automatically by the linker if |
| the following two conditions are met: |
| <ul> |
| <li>The address of a label is taken by means of the <code>gs</code> modifier |
| (short for <em>generate stubs</em>) like so: |
| <pre class="example"> LDI r24, lo8(gs(<var>func</var>)) |
| LDI r25, hi8(gs(<var>func</var>)) |
| </pre> |
| <li>The final location of that label is in a code segment |
| <em>outside</em> the segment where the stubs are located. |
| </ul> |
| |
| <li>The compiler emits such <code>gs</code> modifiers for code labels in the |
| following situations: |
| <ul> |
| <li>Taking address of a function or code label. |
| <li>Computed goto. |
| <li>If prologue-save function is used, see <samp><span class="option">-mcall-prologues</span></samp> |
| command-line option. |
| <li>Switch/case dispatch tables. If you do not want such dispatch |
| tables you can specify the <samp><span class="option">-fno-jump-tables</span></samp> command-line option. |
| <li>C and C++ constructors/destructors called during startup/shutdown. |
| <li>If the tools hit a <code>gs()</code> modifier explained above. |
| </ul> |
| |
| <li>Jumping to non-symbolic addresses like so is <em>not</em> supported: |
| |
| <pre class="example"> int main (void) |
| { |
| /* Call function at word address 0x2 */ |
| return ((int(*)(void)) 0x2)(); |
| } |
| </pre> |
| <p>Instead, a stub has to be set up, i.e. the function has to be called |
| through a symbol (<code>func_4</code> in the example): |
| |
| <pre class="example"> int main (void) |
| { |
| extern int func_4 (void); |
| |
| /* Call function at byte address 0x4 */ |
| return func_4(); |
| } |
| </pre> |
| <p>and the application be linked with <code>-Wl,--defsym,func_4=0x4</code>. |
| Alternatively, <code>func_4</code> can be defined in the linker script. |
| </ul> |
| |
| <h5 class="subsubsection">3.17.4.2 Handling of the <code>RAMPD</code>, <code>RAMPX</code>, <code>RAMPY</code> and <code>RAMPZ</code> Special Function Registers</h5> |
| |
| <p><a name="index-g_t_0040code_007bRAMPD_007d-1164"></a><a name="index-g_t_0040code_007bRAMPX_007d-1165"></a><a name="index-g_t_0040code_007bRAMPY_007d-1166"></a><a name="index-g_t_0040code_007bRAMPZ_007d-1167"></a>Some AVR devices support memories larger than the 64 KiB range |
| that can be accessed with 16-bit pointers. To access memory locations |
| outside this 64 KiB range, the contentent of a <code>RAMP</code> |
| register is used as high part of the address: |
| The <code>X</code>, <code>Y</code>, <code>Z</code> address register is concatenated |
| with the <code>RAMPX</code>, <code>RAMPY</code>, <code>RAMPZ</code> special function |
| register, respectively, to get a wide address. Similarly, |
| <code>RAMPD</code> is used together with direct addressing. |
| |
| <ul> |
| <li>The startup code initializes the <code>RAMP</code> special function |
| registers with zero. |
| |
| <li>If a <a href="AVR-Named-Address-Spaces.html#AVR-Named-Address-Spaces">named address space</a> other than |
| generic or <code>__flash</code> is used, then <code>RAMPZ</code> is set |
| as needed before the operation. |
| |
| <li>If the device supports RAM larger than 64 KiB and the compiler |
| needs to change <code>RAMPZ</code> to accomplish an operation, <code>RAMPZ</code> |
| is reset to zero after the operation. |
| |
| <li>If the device comes with a specific <code>RAMP</code> register, the ISR |
| prologue/epilogue saves/restores that SFR and initializes it with |
| zero in case the ISR code might (implicitly) use it. |
| |
| <li>RAM larger than 64 KiB is not supported by GCC for AVR targets. |
| If you use inline assembler to read from locations outside the |
| 16-bit address range and change one of the <code>RAMP</code> registers, |
| you must reset it to zero after the access. |
| |
| </ul> |
| |
| <h5 class="subsubsection">3.17.4.3 AVR Built-in Macros</h5> |
| |
| <p>GCC defines several built-in macros so that the user code can test |
| for the presence or absence of features. Almost any of the following |
| built-in macros are deduced from device capabilities and thus |
| triggered by the <code>-mmcu=</code> command-line option. |
| |
| <p>For even more AVR-specific built-in macros see |
| <a href="AVR-Named-Address-Spaces.html#AVR-Named-Address-Spaces">AVR Named Address Spaces</a> and <a href="AVR-Built_002din-Functions.html#AVR-Built_002din-Functions">AVR Built-in Functions</a>. |
| |
| <dl> |
| <dt><code>__AVR_ARCH__</code><dd>Build-in macro that resolves to a decimal number that identifies the |
| architecture and depends on the <code>-mmcu=</code><var>mcu</var> option. |
| Possible values are: |
| |
| <p><code>2</code>, <code>25</code>, <code>3</code>, <code>31</code>, <code>35</code>, |
| <code>4</code>, <code>5</code>, <code>51</code>, <code>6</code>, <code>102</code>, <code>104</code>, |
| <code>105</code>, <code>106</code>, <code>107</code> |
| |
| <p>for <var>mcu</var>=<code>avr2</code>, <code>avr25</code>, <code>avr3</code>, |
| <code>avr31</code>, <code>avr35</code>, <code>avr4</code>, <code>avr5</code>, <code>avr51</code>, |
| <code>avr6</code>, <code>avrxmega2</code>, <code>avrxmega4</code>, <code>avrxmega5</code>, |
| <code>avrxmega6</code>, <code>avrxmega7</code>, respectively. |
| If <var>mcu</var> specifies a device, this built-in macro is set |
| accordingly. For example, with <code>-mmcu=atmega8</code> the macro will be |
| defined to <code>4</code>. |
| |
| <br><dt><code>__AVR_</code><var>Device</var><code>__</code><dd>Setting <code>-mmcu=</code><var>device</var> defines this built-in macro which reflects |
| the device's name. For example, <code>-mmcu=atmega8</code> defines the |
| built-in macro <code>__AVR_ATmega8__</code>, <code>-mmcu=attiny261a</code> defines |
| <code>__AVR_ATtiny261A__</code>, etc. |
| |
| <p>The built-in macros' names follow |
| the scheme <code>__AVR_</code><var>Device</var><code>__</code> where <var>Device</var> is |
| the device name as from the AVR user manual. The difference between |
| <var>Device</var> in the built-in macro and <var>device</var> in |
| <code>-mmcu=</code><var>device</var> is that the latter is always lowercase. |
| |
| <p>If <var>device</var> is not a device but only a core architecture like |
| <code>avr51</code>, this macro will not be defined. |
| |
| <br><dt><code>__AVR_XMEGA__</code><dd>The device / architecture belongs to the XMEGA family of devices. |
| |
| <br><dt><code>__AVR_HAVE_ELPM__</code><dd>The device has the the <code>ELPM</code> instruction. |
| |
| <br><dt><code>__AVR_HAVE_ELPMX__</code><dd>The device has the <code>ELPM R</code><var>n</var><code>,Z</code> and <code>ELPM |
| R</code><var>n</var><code>,Z+</code> instructions. |
| |
| <br><dt><code>__AVR_HAVE_MOVW__</code><dd>The device has the <code>MOVW</code> instruction to perform 16-bit |
| register-register moves. |
| |
| <br><dt><code>__AVR_HAVE_LPMX__</code><dd>The device has the <code>LPM R</code><var>n</var><code>,Z</code> and |
| <code>LPM R</code><var>n</var><code>,Z+</code> instructions. |
| |
| <br><dt><code>__AVR_HAVE_MUL__</code><dd>The device has a hardware multiplier. |
| |
| <br><dt><code>__AVR_HAVE_JMP_CALL__</code><dd>The device has the <code>JMP</code> and <code>CALL</code> instructions. |
| This is the case for devices with at least 16 KiB of program |
| memory. |
| |
| <br><dt><code>__AVR_HAVE_EIJMP_EICALL__</code><dt><code>__AVR_3_BYTE_PC__</code><dd>The device has the <code>EIJMP</code> and <code>EICALL</code> instructions. |
| This is the case for devices with more than 128 KiB of program memory. |
| This also means that the program counter |
| (PC) is 3 bytes wide. |
| |
| <br><dt><code>__AVR_2_BYTE_PC__</code><dd>The program counter (PC) is 2 bytes wide. This is the case for devices |
| with up to 128 KiB of program memory. |
| |
| <br><dt><code>__AVR_HAVE_8BIT_SP__</code><dt><code>__AVR_HAVE_16BIT_SP__</code><dd>The stack pointer (SP) register is treated as 8-bit respectively |
| 16-bit register by the compiler. |
| The definition of these macros is affected by <code>-mtiny-stack</code>. |
| |
| <br><dt><code>__AVR_HAVE_SPH__</code><dt><code>__AVR_SP8__</code><dd>The device has the SPH (high part of stack pointer) special function |
| register or has an 8-bit stack pointer, respectively. |
| The definition of these macros is affected by <code>-mmcu=</code> and |
| in the cases of <code>-mmcu=avr2</code> and <code>-mmcu=avr25</code> also |
| by <code>-msp8</code>. |
| |
| <br><dt><code>__AVR_HAVE_RAMPD__</code><dt><code>__AVR_HAVE_RAMPX__</code><dt><code>__AVR_HAVE_RAMPY__</code><dt><code>__AVR_HAVE_RAMPZ__</code><dd>The device has the <code>RAMPD</code>, <code>RAMPX</code>, <code>RAMPY</code>, |
| <code>RAMPZ</code> special function register, respectively. |
| |
| <br><dt><code>__NO_INTERRUPTS__</code><dd>This macro reflects the <code>-mno-interrupts</code> command line option. |
| |
| <br><dt><code>__AVR_ERRATA_SKIP__</code><dt><code>__AVR_ERRATA_SKIP_JMP_CALL__</code><dd>Some AVR devices (AT90S8515, ATmega103) must not skip 32-bit |
| instructions because of a hardware erratum. Skip instructions are |
| <code>SBRS</code>, <code>SBRC</code>, <code>SBIS</code>, <code>SBIC</code> and <code>CPSE</code>. |
| The second macro is only defined if <code>__AVR_HAVE_JMP_CALL__</code> is also |
| set. |
| |
| <br><dt><code>__AVR_SFR_OFFSET__=</code><var>offset</var><dd>Instructions that can address I/O special function registers directly |
| like <code>IN</code>, <code>OUT</code>, <code>SBI</code>, etc. may use a different |
| address as if addressed by an instruction to access RAM like <code>LD</code> |
| or <code>STS</code>. This offset depends on the device architecture and has |
| to be subtracted from the RAM address in order to get the |
| respective I/O address. |
| |
| <br><dt><code>__WITH_AVRLIBC__</code><dd>The compiler is configured to be used together with AVR-Libc. |
| See the <code>--with-avrlibc</code> configure option. |
| |
| </dl> |
| |
| </body></html> |
| |
