* avr-tdep.c (avr_scan_prologue): Update comment describing the various
prologue types. Properly scan prologues generated by gcc with the -mcall-prologues option. Add code to scan -mcall-prologues for mega devices.
This commit is contained in:
Theodore A. Roth
parent
b826ae225a
commit
e3d8b00410
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@ -1,3 +1,11 @@
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2003-06-15 Theodore A. Roth <troth@openavr.org>
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* avr-tdep.c (avr_scan_prologue): Update comment describing the various
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prologue types.
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Properly scan prologues generated by gcc with the -mcall-prologues
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option.
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Add code to scan -mcall-prologues for mega devices.
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2003-06-15 Theodore A. Roth <troth@openavr.org>
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* avr-tdep.c (avr_register_byte): Delete function.
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151
gdb/avr-tdep.c
151
gdb/avr-tdep.c
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@ -359,26 +359,81 @@ avr_read_fp (void)
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3) the offsets of saved regs
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This information is stored in the "extra_info" field of the frame_info.
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A typical AVR function prologue might look like this:
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push rXX
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push r28
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push r29
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in r28,__SP_L__
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in r29,__SP_H__
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sbiw r28,<LOCALS_SIZE>
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in __tmp_reg__,__SREG__
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cli
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out __SP_L__,r28
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out __SREG__,__tmp_reg__
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out __SP_H__,r29
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Some devices lack the sbiw instruction, so on those replace this:
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sbiw r28, XX
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with this:
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subi r28,lo8(XX)
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sbci r29,hi8(XX)
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A `-mcall-prologues' prologue look like this:
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ldi r26,<LOCALS_SIZE>
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ldi r27,<LOCALS_SIZE>/265
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ldi r30,pm_lo8(.L_foo_body)
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ldi r31,pm_hi8(.L_foo_body)
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rjmp __prologue_saves__+RRR
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.L_foo_body: */
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A typical AVR function prologue with a frame pointer might look like this:
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push rXX ; saved regs
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...
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push r28
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push r29
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in r28,__SP_L__
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in r29,__SP_H__
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sbiw r28,<LOCALS_SIZE>
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in __tmp_reg__,__SREG__
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cli
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out __SP_L__,r28
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out __SREG__,__tmp_reg__
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out __SP_H__,r29
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A typical AVR function prologue without a frame pointer might look like
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this:
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push rXX ; saved regs
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...
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A main function prologue looks like this:
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ldi r28,lo8(<RAM_ADDR> - <LOCALS_SIZE>)
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ldi r29,hi8(<RAM_ADDR> - <LOCALS_SIZE>)
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out __SP_H__,r29
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out __SP_L__,r28
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A signal handler prologue looks like this:
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push __zero_reg__
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push __tmp_reg__
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in __tmp_reg__, __SREG__
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push __tmp_reg__
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clr __zero_reg__
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push rXX ; save registers r18:r27, r30:r31
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...
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push r28 ; save frame pointer
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push r29
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in r28, __SP_L__
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in r29, __SP_H__
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sbiw r28, <LOCALS_SIZE>
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out __SP_H__, r29
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out __SP_L__, r28
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A interrupt handler prologue looks like this:
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sei
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push __zero_reg__
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push __tmp_reg__
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in __tmp_reg__, __SREG__
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push __tmp_reg__
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clr __zero_reg__
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push rXX ; save registers r18:r27, r30:r31
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...
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push r28 ; save frame pointer
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push r29
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in r28, __SP_L__
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in r29, __SP_H__
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sbiw r28, <LOCALS_SIZE>
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cli
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out __SP_H__, r29
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sei
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out __SP_L__, r28
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A `-mcall-prologues' prologue looks like this (Note that the megas use a
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jmp instead of a rjmp, thus the prologue is one word larger since jmp is a
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32 bit insn and rjmp is a 16 bit insn):
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ldi r26,lo8(<LOCALS_SIZE>)
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ldi r27,hi8(<LOCALS_SIZE>)
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ldi r30,pm_lo8(.L_foo_body)
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ldi r31,pm_hi8(.L_foo_body)
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rjmp __prologue_saves__+RRR
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.L_foo_body: */
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static void
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avr_scan_prologue (struct frame_info *fi)
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@ -457,10 +512,9 @@ avr_scan_prologue (struct frame_info *fi)
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}
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}
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/* Scanning `-mcall-prologues' prologue
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FIXME: mega prologue have a 12 bytes long */
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/* Scanning `-mcall-prologues' prologue */
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while (prologue_len <= 12) /* I'm use while to avoit many goto's */
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while (1) /* Using a while to avoid many goto's */
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{
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int loc_size;
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int body_addr;
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@ -490,9 +544,6 @@ avr_scan_prologue (struct frame_info *fi)
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break;
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body_addr |= ((insn & 0xf) | ((insn & 0x0f00) >> 4)) << 8;
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if (body_addr != (prologue_start + 10) / 2)
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break;
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msymbol = lookup_minimal_symbol ("__prologue_saves__", NULL, NULL);
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if (!msymbol)
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break;
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@ -500,15 +551,33 @@ avr_scan_prologue (struct frame_info *fi)
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/* FIXME: prologue for mega have a JMP instead of RJMP */
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insn = EXTRACT_INSN (&prologue[vpc + 8]);
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/* rjmp __prologue_saves__+RRR */
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if ((insn & 0xf000) != 0xc000)
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break;
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if ((insn & 0xf000) == 0xc000)
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{
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/* Extract PC relative offset from RJMP */
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i = (insn & 0xfff) | (insn & 0x800 ? (-1 ^ 0xfff) : 0);
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/* Convert offset to byte addressable mode */
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i *= 2;
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/* Destination address */
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i += prologue_start + 10;
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if (body_addr != (prologue_start + 10) / 2)
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break;
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}
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/* jmp __prologue_saves__+RRR */
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else if ((insn & 0xfe0e) == 0x940c)
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{
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/* Extract absolute PC address from JMP */
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i = (((insn & 0x1) | ((insn & 0x1f0) >> 3) << 16)
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| (EXTRACT_INSN (&prologue[vpc + 10]) & 0xffff));
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/* Convert address to byte addressable mode */
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i *= 2;
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if (body_addr != (prologue_start + 12)/2)
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break;
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}
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else
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break;
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/* Extract PC relative offset from RJMP */
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i = (insn & 0xfff) | (insn & 0x800 ? (-1 ^ 0xfff) : 0);
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/* Convert offset to byte addressable mode */
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i *= 2;
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/* Destination address */
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i += vpc + prologue_start + 10;
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/* Resovle offset (in words) from __prologue_saves__ symbol.
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Which is a pushes count in `-mcall-prologues' mode */
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num_pushes = AVR_MAX_PUSHES - (i - SYMBOL_VALUE_ADDRESS (msymbol)) / 2;
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@ -606,9 +675,9 @@ avr_scan_prologue (struct frame_info *fi)
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sbci r29,hi8(XX)
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in __tmp_reg__,__SREG__
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cli
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out __SP_L__,r28
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out __SP_H__,r29
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out __SREG__,__tmp_reg__
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out __SP_H__,r29 */
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out __SP_L__,r28 */
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if (scan_stage == 2 && vpc + 12 <= prologue_len)
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{
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@ -616,19 +685,19 @@ avr_scan_prologue (struct frame_info *fi)
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unsigned char img[] = {
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0x0f, 0xb6, /* in r0,0x3f */
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0xf8, 0x94, /* cli */
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0xcd, 0xbf, /* out 0x3d,r28 ; SPL */
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0xde, 0xbf, /* out 0x3e,r29 ; SPH */
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0x0f, 0xbe, /* out 0x3f,r0 ; SREG */
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0xde, 0xbf /* out 0x3e,r29 ; SPH */
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0xcd, 0xbf /* out 0x3d,r28 ; SPL */
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};
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unsigned char img_sig[] = {
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0xcd, 0xbf, /* out 0x3d,r28 ; SPL */
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0xde, 0xbf /* out 0x3e,r29 ; SPH */
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0xde, 0xbf, /* out 0x3e,r29 ; SPH */
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0xcd, 0xbf /* out 0x3d,r28 ; SPL */
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};
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unsigned char img_int[] = {
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0xf8, 0x94, /* cli */
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0xcd, 0xbf, /* out 0x3d,r28 ; SPL */
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0xde, 0xbf, /* out 0x3e,r29 ; SPH */
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0x78, 0x94, /* sei */
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0xde, 0xbf /* out 0x3e,r29 ; SPH */
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0xcd, 0xbf /* out 0x3d,r28 ; SPL */
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};
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insn = EXTRACT_INSN (&prologue[vpc]);
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