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9.4 Establishing a Stack Frame for Various CPU Architectures
Since we eluded to the establishment of a stack frame in the previous section, we’ll very briefly show
how to set up an application-owned stack for ARM, MIPS, PowerPC and Coldfire. Note that it is beyond the
scope of this document to go into a lot of target-specific detail; however, the basic setup of a non-monitor-owned
stack is essential. Each of these examples are included in the demo application code under the uMon source
code distribution, they are shown here simply for completeness of the discussion. Each of these startup points
uses the “start” tag and assumes that the first ‘C’ function is Cstart(). They simply establish the stack pointer to
be the end of the AppStack[] array, then jump to Cstart(). This sort of pre-C code is generally part of a compiler
package called crt0.s; however, it is provide here to provide independence from that linkage.
9.4.1 ARM-Based Stack Setup
.extern AppStack
.extern Cstart
.global start
.text
start:
ldr sp, =(AppStack + 4096 - 16)
jump_to_c:
bl Cstart
9.4.2 MIPS-Based Stack Setup
#define sp
#define k0
$29
$26
.extern AppStack
.extern Cstart
.global start
.text
.set noreorder
start:
la
addiu
addiu
sp, AppStack
sp, 4096
sp, -16
la
j
nop
k0,Cstart
k0
goToC:
9.4.3 Coldfire-Based Stack Setup
.extern
.extern
.global
AppStack
Cstart
start
.text
start:
move.l #AppStack+(4096-16),%sp
jsr
Cstart
9.4.4 PowerPC-Based Stack Setup
#define
#define
#define
sp
r0
r7
1
0
7
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