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m68k: add MSP detection support for stack pointer swap helpers

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On m68k there are two varities of stack pointers: USP with SSP or ISP/MSP.

Only the 68020/30/40 support the MSP register the stack swap helpers don't
support this feature.

This patch adds this support, as well as comments to CPUM68KState to
make it clear how stacks are handled

Signed-off-by: Lucien Murray-Pitts <lucienmp.qemu@gmail.com>
Signed-off-by: BALATON Zoltan <balaton@eik.bme.hu>
Message-Id: <c61ad2d8b39f3b03b431819b6bf602a1c332b921.1612137712.git.balaton@eik.bme.hu>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
This commit is contained in:
Lucien Murray-Pitts 2021-02-01 01:01:52 +01:00 committed by Laurent Vivier
parent 8df0e6aeda
commit 7525a9b94c
3 changed files with 11 additions and 2 deletions
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1
target/m68k/cpu.c
View file

@ -160,6 +160,7 @@ static void m68020_cpu_initfn(Object *obj)
m68k_set_feature(env, M68K_FEATURE_FPU);
m68k_set_feature(env, M68K_FEATURE_CAS);
m68k_set_feature(env, M68K_FEATURE_CHK2);
m68k_set_feature(env, M68K_FEATURE_MSP);
}
/*

9
target/m68k/cpu.h
View file

@ -85,7 +85,13 @@ typedef struct CPUM68KState {
uint32_t pc;
uint32_t sr;
/* SSP and USP. The current_sp is stored in aregs[7], the other here. */
/*
* The 68020/30/40 support two supervisor stacks, ISP and MSP.
* The 68000/10, Coldfire, and CPU32 only have USP/SSP.
*
* The current_sp is stored in aregs[7], the other here.
* The USP, SSP, and if used the additional ISP for 68020/30/40.
*/
int current_sp;
uint32_t sp[3];
@ -484,6 +490,7 @@ enum m68k_features {
M68K_FEATURE_CF_EMAC,
M68K_FEATURE_CF_EMAC_B, /* Revision B EMAC (dual accumulate). */
M68K_FEATURE_USP, /* User Stack Pointer. (680[012346]0, ISA A+, B or C).*/
M68K_FEATURE_MSP, /* Master Stack Pointer. (680[234]0) */
M68K_FEATURE_EXT_FULL, /* 68020+ full extension word. */
M68K_FEATURE_WORD_INDEX, /* word sized address index registers. */
M68K_FEATURE_SCALED_INDEX, /* scaled address index registers. */

3
target/m68k/helper.c
View file

@ -463,7 +463,8 @@ void m68k_switch_sp(CPUM68KState *env)
env->sp[env->current_sp] = env->aregs[7];
if (m68k_feature(env, M68K_FEATURE_M68000)) {
if (env->sr & SR_S) {
if (env->sr & SR_M) {
/* SR:Master-Mode bit unimplemented then ISP is not available */
if (!m68k_feature(env, M68K_FEATURE_MSP) || env->sr & SR_M) {
new_sp = M68K_SSP;
} else {
new_sp = M68K_ISP;